485BPOS

Securities Act of 1933 Registration No. 002-93601

Investment Company Act of 1940 Registration No. 811-04118

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 x

o Pre-Effective Amendment No.  ______

x Post-Effective Amendment No.  141

and

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940 x

x Amendment No.  141

Fidelity Securities Fund

 (Exact Name of Registrant as Specified in Charter)

245 Summer Street, Boston, Massachusetts 02210

(Address of Principal Executive Offices)(Zip Code)

Registrant’s Telephone Number: 617-563-7000

Cynthia Lo Bessette, Secretary

245 Summer Street

Boston, Massachusetts 02210

(Name and Address of Agent for Service)

It is proposed that this filing will become effective immediately upon filing pursuant to paragraph (b) of Rule 485.

EXHIBIT INDEX

Exhibit	Exhibit No.
XBRL Instance Document	EX-101.INS
XBRL Taxonomy Extension Schema Document	EX-101.SCH
XBRL Taxonomy Extension Calculation Linkbase Document	EX-101.CAL
XBRL Taxonomy Extension Definition Linkbase Document	EX-101.DEF
XBRL Taxonomy Extension Labels Linkbase Document	EX-101.LAB
XBRL Taxonomy Extension Presentation Linkbase Document	EX-101.PRE

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for the effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Post-Effective Amendment No. 141 to the Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Boston, and Commonwealth of Massachusetts, on the 15th day of October 2019.

	Fidelity Securities Fund
	By	/s/Stacie M. Smith
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||		Stacie M. Smith, President

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

(Signature)		(Title)	(Date)
/s/Stacie M. Smith		President and Treasurer	October 15, 2019
Stacie M. Smith		(Principal Executive Officer)
/s/ John J. Burke III		Chief Financial Officer	October 15, 2019
John J. Burke III		(Principal Financial Officer)
/s/Jonathan Chiel	*	Trustee	October 15, 2019
Jonathan Chiel
/s/James C. Curvey	*	Trustee	October 15, 2019
James C. Curvey
/s/Dennis J. Dirks	*	Trustee	October 15, 2019
Dennis J. Dirks
/s/Donald F. Donahue	*	Trustee	October 15, 2019
Donald F. Donahue
/s/Alan J. Lacy	*	Trustee	October 15, 2019
Alan J. Lacy
/s/Ned C. Lautenbach	*	Trustee	October 15, 2019
Ned C. Lautenbach
/s/Joseph Mauriello	*	Trustee	October 15, 2019
Joseph Mauriello
/s/Cornelia M. Small	*	Trustee	October 15, 2019
Cornelia M. Small
/s/Garnett A. Smith	*	Trustee	October 15, 2019
Garnett A. Smith
/s/David M. Thomas	*	Trustee	October 15, 2019
David M. Thomas

*	By:	/s/Megan C. Johnson
		Megan C. Johnson, pursuant to powers of attorney dated October 5, 2016 and January 1, 2019 and filed herewith.

POWER OF ATTORNEY

I, the undersigned Trustee of the following investment companies:

Fidelity Advisor Series VIII Fidelity Concord Street Trust Fidelity Investment Trust Fidelity Puritan Trust Fidelity Securities Fund Variable Insurance Products Fund

in addition to any other Fidelity Fund for which the undersigned individual serves as Director or Trustee (collectively, the “Funds”), hereby constitute and appoint Thomas C. Bogle, Marc R. Bryant, John V. O’Hanlon, Robert W. Helm, Megan C. Johnson, and Anthony H. Zacharski, each of them singly, my true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for me and in my name in the appropriate capacity, all Registration Statements of the Funds on Form N-1A, or any successors thereto, any and all subsequent Amendments, Pre-Effective Amendments, or Post-Effective Amendments to said Registration Statements or any successors thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in my name and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940, and all related requirements of the Securities and Exchange Commission.  I hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.  This power of attorney is effective for all documents filed on or after October 5, 2016.

WITNESS my hand on this 5^th day of October, 2016.

/s/Jonathan Chiel

Jonathan Chiel

POWER OF ATTORNEY

We, the undersigned Directors or Trustees, as the case may be, of the following investment companies:

Fidelity Advisor Series I Fidelity Advisor Series VII Fidelity Advisor Series VIII Fidelity Beacon Street Trust Fidelity Capital Trust Fidelity Central Investment Portfolios LLC Fidelity Commonwealth Trust Fidelity Commonwealth Trust II Fidelity Concord Street Trust Fidelity Congress Street Fund Fidelity Contrafund Fidelity Covington Trust Fidelity Destiny Portfolios Fidelity Devonshire Trust Fidelity Exchange Fund Fidelity Financial Trust Fidelity Hanover Street Trust Fidelity Hastings Street Trust Fidelity Investment Trust Fidelity Magellan Fund Fidelity Mt. Vernon Street Trust Fidelity Puritan Trust Fidelity Securities Fund Fidelity Select Portfolios Fidelity Summer Street Trust Fidelity Trend Fund Variable Insurance Products Fund Variable Insurance Products Fund II Variable Insurance Products Fund III Variable Insurance Products Fund IV

in addition to any other investment company for which Fidelity Management & Research Company (“FMR”) or an affiliate acts as investment adviser and for which the undersigned individuals serve as Directors or Trustees (collectively, the “Funds”), hereby revoke all previous powers of attorney we have given to sign and otherwise act in our names and behalf in matters involving any investment company for which FMR or an affiliate acts as investment adviser and hereby constitute and appoint Thomas C. Bogle, John V. O’Hanlon, Robert W. Helm, Megan C. Johnson, and Anthony H. Zacharski, each of them singly, our true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for us and in our names in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, or any successors thereto, any and all subsequent Amendments, Pre-Effective Amendments, or Post-Effective Amendments to said Registration Statements or any successors thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in our names and behalf in connection therewith as said attorneys–in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940, and all related requirements of the Securities and Exchange Commission.  We hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof.  This power of attorney is effective for all documents filed on or after January 1, 2019.

WITNESS our hands on this first day of January 2019.

/s/James C. Curvey	/s/Joseph Mauriello
James C. Curvey	Joseph Mauriello
/s/Dennis J. Dirks	/s/Cornelia M. Small
Dennis J. Dirks	Cornelia M. Small
/s/Donald F. Donahue	/s/Garnett A. Smith
Donald F. Donahue	Garnett A. Smith
/s/Alan J. Lacy	/s/David M. Thomas
Alan J. Lacy	David M. Thomas
/s/Ned C. Lautenbach
Ned C. Lautenbach

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 | Fidelity® Series Blue Chip Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Series Blue Chip Growth Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks growth of capital over the long term.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 53% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

53.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.fidelity.com</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	11.75%	March 31, 2017
Lowest Quarter Return	-14.21%	December 31, 2018
Year-to-Date Return	20.19%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 | Fidelity® Series Blue Chip Growth Fund | Fidelity Series Blue Chip Growth Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

none

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

Total annual operating expenses

rr_ExpensesOverAssets

none

1 year

rr_ExpenseExampleYear01

none

3 years

rr_ExpenseExampleYear03

none

5 years

rr_ExpenseExampleYear05

none

10 years

rr_ExpenseExampleYear10

none

2014

rr_AnnualReturn2014

14.70%

2015

rr_AnnualReturn2015

6.84%

2016

rr_AnnualReturn2016

1.58%

2017

rr_AnnualReturn2017

35.94%

2018

rr_AnnualReturn2018

4.65%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

20.19%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2017

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.75%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(14.21%)

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 07, 2013

07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 | Fidelity® Series Blue Chip Growth Fund | Return Before Taxes | Fidelity Series Blue Chip Growth Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Series Blue Chip Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

4.65%

Past 5 years

rr_AverageAnnualReturnYear05

12.11%

Since Inception

rr_AverageAnnualReturnSinceInception

13.13%

^[1]

07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 | Fidelity® Series Blue Chip Growth Fund | After Taxes on Distributions | Fidelity Series Blue Chip Growth Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Series Blue Chip Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

1.41%

Past 5 years

rr_AverageAnnualReturnYear05

10.05%

Since Inception

rr_AverageAnnualReturnSinceInception

11.10%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 07, 2013

07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 | Fidelity® Series Blue Chip Growth Fund | After Taxes on Distributions and Sales | Fidelity Series Blue Chip Growth Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Series Blue Chip Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

5.40%

Past 5 years

rr_AverageAnnualReturnYear05

9.47%

Since Inception

rr_AverageAnnualReturnSinceInception

10.34%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 07, 2013

07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 | Fidelity® Series Blue Chip Growth Fund | Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(1.51%)

Past 5 years

rr_AverageAnnualReturnYear05

10.40%

Since Inception

rr_AverageAnnualReturnSinceInception

11.48%

^[1]

[1] From November 7, 2013

XML

07.31 Fidelity Flex Large Cap Growth Fund PRO-05 | Fidelity Flex Large Cap Growth Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity Flex℠ Large Cap Growth Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks long-term growth of capital.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity Flex Large Cap Growth Fund}	07.31 Fidelity Flex Large Cap Growth Fund PRO-05 Fidelity Flex Large Cap Growth Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity Flex Large Cap Growth Fund}	07.31 Fidelity Flex Large Cap Growth Fund PRO-05 Fidelity Flex Large Cap Growth Fund Fidelity Flex Large Cap Growth Fund
Management fee	none
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	none	[1]

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. This example does not include any fees paid at the fee-based account or plan level. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity Flex Large Cap Growth Fund}	07.31 Fidelity Flex Large Cap Growth Fund PRO-05 Fidelity Flex Large Cap Growth Fund Fidelity Flex Large Cap Growth Fund USD ($)
1 year	none
3 years	none
5 years	none
10 years	none

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 55% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with large market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 1000^® Index or the S&P 500^® Index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance. The performance shown does not reflect the impact of any fees paid at the fee-based account or plan level.

Visit www.401k.com and log in for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	8.53%	June 30, 2018
Lowest Quarter Return	-17.56%	December 31, 2018
Year-to-Date Return	21.41%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity Flex Large Cap Growth Fund} - 07.31 Fidelity Flex Large Cap Growth Fund PRO-05 - Fidelity Flex Large Cap Growth Fund	Past 1 year	Since Inception	[1]	Inception Date
Fidelity Flex Large Cap Growth Fund				Mar. 08, 2017
Fidelity Flex Large Cap Growth Fund | Return Before Taxes	(0.80%)	12.61%
Fidelity Flex Large Cap Growth Fund | After Taxes on Distributions	(1.78%)	11.85%		Mar. 08, 2017
Fidelity Flex Large Cap Growth Fund | After Taxes on Distributions and Sales	none	9.59%		Mar. 08, 2017
Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)	(1.51%)	9.87%

[1] The fund is available only to certain fee-based accounts offered by Fidelity. Managed account clients, retirement plans, plan sponsors and/or plan participants pay a wrap fee that covers investment advisory and administrative services.

[1] From March 8, 2017

XML

07.31 Fidelity Real Estate Income Fund Retail PRO-07 | Fidelity Real Estate Income Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Real Estate Income Fund</b>/Fidelity® Real Estate Income Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks higher than average income. As a secondary objective, the fund also seeks capital growth.

As a secondary objective, the fund also seeks capital growth.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity Real Estate Income Fund}	07.31 Fidelity Real Estate Income Fund Retail PRO-07 Fidelity Real Estate Income Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity Real Estate Income Fund}	07.31 Fidelity Real Estate Income Fund Retail PRO-07 Fidelity Real Estate Income Fund Fidelity Real Estate Income Fund
Management fee	0.54%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.21%
Total annual operating expenses	0.75%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity Real Estate Income Fund}	07.31 Fidelity Real Estate Income Fund Retail PRO-07 Fidelity Real Estate Income Fund Fidelity Real Estate Income Fund USD ($)
1 year	$ 77
3 years	240
5 years	417
10 years	$ 930

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 17% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in preferred and common stocks of real estate investment trusts (REITs); debt securities of real estate entities; and commercial and other mortgage-backed securities, with an emphasis on lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Normally investing at least 80% of assets in securities of companies principally engaged in the real estate industry and other real estate related investments.

• Investing in domestic and foreign issuers.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Real Estate Industry Concentration. Changes in real estate values or economic downturns can have a significant negative effect on issuers in the real estate industry. The value of securities of issuers in the real estate industry can be affected by changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, and the management skill and creditworthiness of the issuer.

• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments and can be difficult to resell. Lower-quality debt securities can be thinly traded or have restrictions on resale, making them difficult to sell at an acceptable price, and often are considered to be speculative.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	20.55%	June 30, 2009
Lowest Quarter Return	-5.91%	September 30, 2011
Year-to-Date Return	11.60%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity Real Estate Income Fund} - 07.31 Fidelity Real Estate Income Fund Retail PRO-07 - Fidelity Real Estate Income Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Real Estate Income Fund | Return Before Taxes	(0.64%)	6.10%	11.76%
Fidelity Real Estate Income Fund | After Taxes on Distributions	(2.58%)	3.85%	9.45%
Fidelity Real Estate Income Fund | After Taxes on Distributions and Sales	0.11%	3.83%	8.68%
S&P 500® Index(reflects no deduction for fees, expenses, or taxes)	(4.38%)	8.49%	13.12%
Fidelity Real Estate Income Composite Index℠(reflects no deduction for fees, expenses, or taxes)	(4.06%)	5.82%	11.35%

XML

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Real Estate Income Fund</b>/Fidelity Advisor® Real Estate Income Fund A, M, C, I, Z</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks higher than average income. As a secondary objective, the fund also seeks capital growth.

As a secondary objective, the fund also seeks capital growth.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund. In addition to the fees and expenses described below, your broker may also require you to pay brokerage commissions on purchases and sales of certain share classes of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity^® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 28 of the prospectus. Different intermediaries may provide additional waivers or reductions of the sales charge. Please see “Sales Charge Waiver Policies Applied by Certain Intermediaries” in the “Appendix” section of the prospectus.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(fees paid directly from your investment)</p>

Shareholder Fees {- Fidelity Real Estate Income Fund} - 07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 - Fidelity Real Estate Income Fund	Fidelity Advisor Real Estate Income Fund: Class A		Fidelity Advisor Real Estate Income Fund: Class M		Fidelity Advisor Real Estate Income Fund: Class C		Fidelity Advisor Real Estate Income Fund: Class I	Fidelity Advisor Real Estate Income Fund: Class Z
Maximum sales charge (load) on purchases (as a % of offering price)	4.00%		4.00%		none		none	none
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)	none	[1]	none	[1]	1.00%	[2]	none	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity Real Estate Income Fund} - 07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 - Fidelity Real Estate Income Fund	Fidelity Advisor Real Estate Income Fund: Class A	Fidelity Advisor Real Estate Income Fund: Class M	Fidelity Advisor Real Estate Income Fund: Class C	Fidelity Advisor Real Estate Income Fund: Class I	Fidelity Advisor Real Estate Income Fund: Class Z
Management fee	0.54%	0.54%	0.54%	0.54%	0.54%
Distribution and/or Service (12b-1) fees	0.25%	0.25%	1.00%	none	none
Other expenses	0.22%	0.25%	0.22%	0.21%	0.08%
Total annual operating expenses	1.01%	1.04%	1.76%	0.75%	0.62%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity Real Estate Income Fund} - 07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 - Fidelity Real Estate Income Fund - USD ($)	Fidelity Advisor Real Estate Income Fund: Class A	Fidelity Advisor Real Estate Income Fund: Class M	Fidelity Advisor Real Estate Income Fund: Class C	Fidelity Advisor Real Estate Income Fund: Class I	Fidelity Advisor Real Estate Income Fund: Class Z
1 year	$ 499	$ 502	$ 279	$ 77	$ 63
3 years	709	718	554	240	199
5 years	936	951	954	417	346
10 years	$ 1,587	$ 1,620	$ 2,073	$ 930	$ 774

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Hold Shares</p>

Expense Example, No Redemption {- Fidelity Real Estate Income Fund} - 07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 - Fidelity Real Estate Income Fund - USD ($)	Fidelity Advisor Real Estate Income Fund: Class A	Fidelity Advisor Real Estate Income Fund: Class M	Fidelity Advisor Real Estate Income Fund: Class C	Fidelity Advisor Real Estate Income Fund: Class I	Fidelity Advisor Real Estate Income Fund: Class Z
1 Year	$ 499	$ 502	$ 179	$ 77	$ 63
3 Years	709	718	554	240	199
5 Years	936	951	954	417	346
10 Years	$ 1,587	$ 1,620	$ 2,073	$ 930	$ 774

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 17% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in preferred and common stocks of real estate investment trusts (REITs); debt securities of real estate entities; and commercial and other mortgage-backed securities, with an emphasis on lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Normally investing at least 80% of assets in securities of companies principally engaged in the real estate industry and other real estate related investments.

• Investing in domestic and foreign issuers.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Real Estate Industry Concentration. Changes in real estate values or economic downturns can have a significant negative effect on issuers in the real estate industry. The value of securities of issuers in the real estate industry can be affected by changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, and the management skill and creditworthiness of the issuer.

• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments and can be difficult to resell. Lower-quality debt securities can be thinly traded or have restrictions on resale, making them difficult to sell at an acceptable price, and often are considered to be speculative.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit institutional.fidelity.com for more recent performance information.

Performance history will be available for Class Z after Class Z has been in operation for one calendar year.

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	6.67%	March 31, 2012
Lowest Quarter Return	-5.96%	September 30, 2011
Year-to-Date Return	11.36%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity Real Estate Income Fund} - 07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 - Fidelity Real Estate Income Fund	Past 1 year	Past 5 years	Since Inception	[1]	Inception Date
Fidelity Advisor Real Estate Income Fund: Class A | Return Before Taxes	(4.79%)	5.00%	6.95%		Apr. 14, 2010
Fidelity Advisor Real Estate Income Fund: Class A | After Taxes on Distributions	(6.56%)	2.86%	4.73%		Apr. 14, 2010
Fidelity Advisor Real Estate Income Fund: Class A | After Taxes on Distributions and Sales	(2.37%)	3.02%	4.58%		Apr. 14, 2010
Fidelity Advisor Real Estate Income Fund: Class M | Return Before Taxes	(4.89%)	4.96%	6.92%		Apr. 14, 2010
Fidelity Advisor Real Estate Income Fund: Class C | Return Before Taxes	(2.59%)	5.05%	6.64%		Apr. 14, 2010
Fidelity Advisor Real Estate Income Fund: Class I | Return Before Taxes	(0.63%)	6.13%	7.73%		Apr. 14, 2010
S&P 500® Index(reflects no deduction for fees, expenses, or taxes)	(4.38%)	8.49%	11.00%
Fidelity Real Estate Income Composite Index℠(reflects no deduction for fees, expenses, or taxes)	(4.06%)	5.82%	6.61%

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Fidelity Advisor Real Estate Income Fund: Class A

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Fidelity Advisor Real Estate Income Fund: Class M

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Fidelity Advisor Real Estate Income Fund: Class C

On Class C shares redeemed less than one year after purchase.

[1] Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

[2] On Class C shares redeemed less than one year after purchase.

[1] From April 14, 2010.

XML

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Small Cap Value Fund</b>/Fidelity Advisor® Small Cap Value Fund A, M, C, I, Z</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund. In addition to the fees and expenses described below, your broker may also require you to pay brokerage commissions on purchases and sales of certain share classes of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity^® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 28 of the prospectus. Different intermediaries may provide additional waivers or reductions of the sales charge. Please see “Sales Charge Waiver Policies Applied by Certain Intermediaries” in the “Appendix” section of the prospectus.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(fees paid directly from your investment)</p>

Shareholder Fees {- Fidelity Small Cap Value Fund} - 07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 - Fidelity Small Cap Value Fund	Fidelity Advisor Small Cap Value Fund: Class A		Fidelity Advisor Small Cap Value Fund: Class M		Fidelity Advisor Small Cap Value Fund: Class C		Fidelity Advisor Small Cap Value Fund: Class I	Fidelity Advisor Small Cap Value Fund: Class Z
Maximum sales charge (load) on purchases (as a % of offering price)	5.75%		3.50%		none		none	none
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)	none	[1]	none	[1]	1.00%	[2]	none	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity Small Cap Value Fund} - 07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 - Fidelity Small Cap Value Fund	Fidelity Advisor Small Cap Value Fund: Class A	Fidelity Advisor Small Cap Value Fund: Class M	Fidelity Advisor Small Cap Value Fund: Class C	Fidelity Advisor Small Cap Value Fund: Class I	Fidelity Advisor Small Cap Value Fund: Class Z
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.43%	0.43%	0.43%	0.43%	0.43%
Distribution and/or Service (12b-1) fees	0.25%	0.50%	1.00%	none	none
Other expenses	0.24%	0.24%	0.25%	0.23%	0.09%
Total annual operating expenses	0.92%	1.17%	1.68%	0.66%	0.52%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity Small Cap Value Fund} - 07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 - Fidelity Small Cap Value Fund - USD ($)	Fidelity Advisor Small Cap Value Fund: Class A	Fidelity Advisor Small Cap Value Fund: Class M	Fidelity Advisor Small Cap Value Fund: Class C	Fidelity Advisor Small Cap Value Fund: Class I	Fidelity Advisor Small Cap Value Fund: Class Z
1 year	$ 663	$ 465	$ 271	$ 67	$ 53
3 years	851	709	530	211	167
5 years	1,055	971	913	368	291
10 years	$ 1,641	$ 1,721	$ 1,987	$ 822	$ 653

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Hold Shares</p>

Expense Example, No Redemption {- Fidelity Small Cap Value Fund} - 07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 - Fidelity Small Cap Value Fund - USD ($)	Fidelity Advisor Small Cap Value Fund: Class A	Fidelity Advisor Small Cap Value Fund: Class M	Fidelity Advisor Small Cap Value Fund: Class C	Fidelity Advisor Small Cap Value Fund: Class I	Fidelity Advisor Small Cap Value Fund: Class Z
1 Year	$ 663	$ 465	$ 171	$ 67	$ 53
3 Years	851	709	530	211	167
5 Years	1,055	971	913	368	291
10 Years	$ 1,641	$ 1,721	$ 1,987	$ 822	$ 653

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 79% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in securities of companies that Fidelity Management & Research Company (FMR) believes are undervalued in the marketplace in relation to factors such as assets, sales, earnings, growth potential, or cash flow, or in relation to securities of other companies in the same industry (stocks of these companies are often called "value" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Value" Investing. "Value" stocks can perform differently from the market as a whole and other types of stocks and can continue to be undervalued by the market for long periods of time.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit institutional.fidelity.com for more recent performance information.

Performance history will be available for Class Z after Class Z has been in operation for one calendar year.

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	25.25%	June 30, 2009
Lowest Quarter Return	-20.24%	September 30, 2011
Year-to-Date Return	12.61%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity Small Cap Value Fund} - 07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 - Fidelity Small Cap Value Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Advisor Small Cap Value Fund: Class A | Return Before Taxes	(20.09%)	2.47%	11.70%
Fidelity Advisor Small Cap Value Fund: Class A | After Taxes on Distributions	(24.87%)	(0.36%)	9.70%
Fidelity Advisor Small Cap Value Fund: Class A | After Taxes on Distributions and Sales	(7.41%)	2.08%	9.75%
Fidelity Advisor Small Cap Value Fund: Class M | Return Before Taxes	(18.38%)	2.70%	11.68%
Fidelity Advisor Small Cap Value Fund: Class C | Return Before Taxes	(16.52%)	2.88%	11.50%
Fidelity Advisor Small Cap Value Fund: Class I | Return Before Taxes	(14.97%)	3.96%	12.67%
Russell 2000® Value Index(reflects no deduction for fees, expenses, or taxes)	(12.86%)	3.61%	10.40%

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Fidelity Advisor Small Cap Value Fund: Class A

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Fidelity Advisor Small Cap Value Fund: Class M

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Fidelity Advisor Small Cap Value Fund: Class C

On Class C shares redeemed less than one year after purchase.

[1] Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

[2] On Class C shares redeemed less than one year after purchase.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Leveraged Company Stock Fund K PRO-05 | Fidelity® Leveraged Company Stock Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Leveraged Company Stock Fund</b>/K</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 53% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

53.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in stocks.

• Normally investing primarily in common stocks of leveraged companies (companies that issue lower-quality debt and other companies with leveraged capital structures).

• Potentially investing in lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

• Highly Leveraged Company Exposure. Leverage can magnify the impact of adverse issuer, political, regulatory, market, or economic developments on a company.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.401k.com and log in </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	38.22%	June 30, 2009
Lowest Quarter Return	-26.59%	September 30, 2011
Year-to-Date Return	22.20%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Market Index Changed

rr_PerformanceTableMarketIndexChanged

<font style="FONT-FAMILY: Times New Roman" size="3">Effective October 1, 2019, the fund's benchmarks will change from the S&P 500® Index and the Credit Suisse Leveraged Equity Index to the Russell Mid Cap Index and the Fidelity U.S. Leveraged Stock Linked Index℠, respectively.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

For the periods ended December 31, 2018

Effective October 1, 2019, the fund's benchmarks will change from the S&P 500^® Index and the Credit Suisse Leveraged Equity Index to the Russell Mid Cap Index and the Fidelity U.S. Leveraged Stock Linked Index℠, respectively.

07.31 Fidelity Leveraged Company Stock Fund K PRO-05 | Fidelity® Leveraged Company Stock Fund | Fidelity Leveraged Company Stock Fund-Class K

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

0.59%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.08%

Total annual operating expenses

rr_ExpensesOverAssets

0.67%

1 year

rr_ExpenseExampleYear01

$ 68

3 years

rr_ExpenseExampleYear03

214

5 years

rr_ExpenseExampleYear05

373

10 years

rr_ExpenseExampleYear10

$ 835

2009

rr_AnnualReturn2009

59.89%

2010

rr_AnnualReturn2010

24.76%

2011

rr_AnnualReturn2011

(10.49%)

2012

rr_AnnualReturn2012

29.04%

2013

rr_AnnualReturn2013

35.26%

2014

rr_AnnualReturn2014

5.71%

2015

rr_AnnualReturn2015

(5.92%)

2016

rr_AnnualReturn2016

7.38%

2017

rr_AnnualReturn2017

21.15%

2018

rr_AnnualReturn2018

(16.33%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

22.20%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

38.22%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(26.59%)

07.31 Fidelity Leveraged Company Stock Fund K PRO-05 | Fidelity® Leveraged Company Stock Fund | Return Before Taxes | Fidelity Leveraged Company Stock Fund-Class K

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Leveraged Company Stock Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class K</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(16.33%)

Past 5 years

rr_AverageAnnualReturnYear05

1.60%

Past 10 years

rr_AverageAnnualReturnYear10

12.93%

07.31 Fidelity Leveraged Company Stock Fund K PRO-05 | Fidelity® Leveraged Company Stock Fund | S&P 500® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.38%)

Past 5 years

rr_AverageAnnualReturnYear05

8.49%

Past 10 years

rr_AverageAnnualReturnYear10

13.12%

07.31 Fidelity Leveraged Company Stock Fund K PRO-05 | Fidelity® Leveraged Company Stock Fund | Credit Suisse Leveraged Equity Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(16.29%)

Past 5 years

rr_AverageAnnualReturnYear05

(0.83%)

Past 10 years

rr_AverageAnnualReturnYear10

10.07%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Value Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Blue Chip Value Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 44% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

44.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in securities of companies that Fidelity Management & Research Company (FMR) believes are undervalued in the marketplace in relation to factors such as assets, sales, earnings, growth potential, or cash flow, or in relation to securities of other companies in the same industry (stocks of these companies are often called "value" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Value" Investing. "Value" stocks can perform differently from the market as a whole and other types of stocks and can continue to be undervalued by the market for long periods of time.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.fidelity.com</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	19.88%	September 30, 2009
Lowest Quarter Return	-20.55%	September 30, 2011
Year-to-Date Return	10.36%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Value Fund | Fidelity Blue Chip Value Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.40%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.25%

Total annual operating expenses

rr_ExpensesOverAssets

0.65%

1 year

rr_ExpenseExampleYear01

$ 66

3 years

rr_ExpenseExampleYear03

208

5 years

rr_ExpenseExampleYear05

362

10 years

rr_ExpenseExampleYear10

$ 810

2009

rr_AnnualReturn2009

27.78%

2010

rr_AnnualReturn2010

10.05%

2011

rr_AnnualReturn2011

(8.02%)

2012

rr_AnnualReturn2012

13.83%

2013

rr_AnnualReturn2013

35.64%

2014

rr_AnnualReturn2014

13.19%

2015

rr_AnnualReturn2015

(1.96%)

2016

rr_AnnualReturn2016

11.19%

2017

rr_AnnualReturn2017

14.87%

2018

rr_AnnualReturn2018

(8.65%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

10.36%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

19.88%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(20.55%)

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Value Fund | Return Before Taxes | Fidelity Blue Chip Value Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Blue Chip Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(8.65%)

Past 5 years

rr_AverageAnnualReturnYear05

5.30%

Past 10 years

rr_AverageAnnualReturnYear10

9.97%

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Value Fund | After Taxes on Distributions | Fidelity Blue Chip Value Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Blue Chip Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(9.07%)

Past 5 years

rr_AverageAnnualReturnYear05

4.93%

Past 10 years

rr_AverageAnnualReturnYear10

9.64%

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Value Fund | After Taxes on Distributions and Sales | Fidelity Blue Chip Value Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Blue Chip Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.78%)

Past 5 years

rr_AverageAnnualReturnYear05

4.12%

Past 10 years

rr_AverageAnnualReturnYear10

8.22%

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Value Fund | Russell 1000® Value Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(8.27%)

Past 5 years

rr_AverageAnnualReturnYear05

5.95%

Past 10 years

rr_AverageAnnualReturnYear10

11.18%

XML

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity Small Cap Value Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Small Cap Value Fund</b>/Fidelity® Small Cap Value Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity Small Cap Value Fund}	07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 Fidelity Small Cap Value Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity Small Cap Value Fund}	07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 Fidelity Small Cap Value Fund Fidelity Small Cap Value Fund
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.43%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.23%
Total annual operating expenses	0.66%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity Small Cap Value Fund}	07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 Fidelity Small Cap Value Fund Fidelity Small Cap Value Fund USD ($)
1 year	$ 67
3 years	211
5 years	368
10 years	$ 822

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 79% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in securities of companies that Fidelity Management & Research Company (FMR) believes are undervalued in the marketplace in relation to factors such as assets, sales, earnings, growth potential, or cash flow, or in relation to securities of other companies in the same industry (stocks of these companies are often called "value" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Value" Investing. "Value" stocks can perform differently from the market as a whole and other types of stocks and can continue to be undervalued by the market for long periods of time.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	25.31%	June 30, 2009
Lowest Quarter Return	-20.18%	September 30, 2011
Year-to-Date Return	12.86%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity Small Cap Value Fund} - 07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 - Fidelity Small Cap Value Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Small Cap Value Fund | Return Before Taxes	(15.04%)	3.95%	12.64%
Fidelity Small Cap Value Fund | After Taxes on Distributions	(20.07%)	1.07%	10.60%
Fidelity Small Cap Value Fund | After Taxes on Distributions and Sales	(4.18%)	3.23%	10.56%
Russell 2000® Value Index(reflects no deduction for fees, expenses, or taxes)	(12.86%)	3.61%	10.40%

XML

07.31 Fidelity OTC K6 Portfolio PRO-02 | Fidelity OTC K6 Portfolio

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® OTC K6 Portfolio</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity OTC K6 Portfolio}	07.31 Fidelity OTC K6 Portfolio PRO-02 Fidelity OTC K6 Portfolio USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity OTC K6 Portfolio}	07.31 Fidelity OTC K6 Portfolio PRO-02 Fidelity OTC K6 Portfolio Fidelity OTC K6 Portfolio
Management fee	0.50%
Distribution and/or Service (12b-1) fees	none
Other expenses	none	[1]
Total annual operating expenses	0.50%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity OTC K6 Portfolio}	07.31 Fidelity OTC K6 Portfolio PRO-02 Fidelity OTC K6 Portfolio Fidelity OTC K6 Portfolio USD ($)
1 year	$ 51
3 years	$ 160

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. For the period from June 13, 2019 to July 31, 2019, the fund's portfolio turnover rate was 5% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities principally traded on NASDAQ^® or an over-the-counter (OTC) market, which has more small and medium-sized companies than other markets.

• Investing more than 25% of total assets in the technology sector.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Technology Industry Concentration. The technology industries can be significantly affected by obsolescence of existing technology, short product cycles, falling prices and profits, competition from new market entrants, and general economic conditions.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. The value of securities of smaller issuers can be more volatile than that of larger issuers.

In addition, the fund is classified as non-diversified under the Investment Company Act of 1940, which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance history will be available for the fund after the fund has been in operation for one calendar year.

[1] Based on estimated amounts for the current fiscal year.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity OTC K6 Portfolio PRO-02 | Fidelity OTC K6 Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® OTC K6 Portfolio</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. For the period from June 13, 2019 to July 31, 2019, the fund's portfolio turnover rate was 5% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

5.00%

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

<font style="FONT-FAMILY: Times New Roman" size="3">Based on estimated amounts for the current fiscal year.</font>

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities principally traded on NASDAQ^® or an over-the-counter (OTC) market, which has more small and medium-sized companies than other markets.

• Investing more than 25% of total assets in the technology sector.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Strategy Portfolio Concentration [Text]

rr_StrategyPortfolioConcentration

<font style="FONT-FAMILY: Times New Roman" size="3">Investing more than 25% of total assets in the technology sector.</font>

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Technology Industry Concentration. The technology industries can be significantly affected by obsolescence of existing technology, short product cycles, falling prices and profits, competition from new market entrants, and general economic conditions.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. The value of securities of smaller issuers can be more volatile than that of larger issuers.

In addition, the fund is classified as non-diversified under the Investment Company Act of 1940, which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

<font style="FONT-FAMILY: Times New Roman" size="3">In addition, the fund is classified as non-diversified under the Investment Company Act of 1940, which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

Performance history will be available for the fund after the fund has been in operation for one calendar year.

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

<font style="FONT-FAMILY: Times New Roman" size="3">Performance history will be available for the fund after the fund has been in operation for one calendar year.</font>

07.31 Fidelity OTC K6 Portfolio PRO-02 | Fidelity OTC K6 Portfolio | Fidelity OTC K6 Portfolio

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

0.50%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

^[1]

Total annual operating expenses

rr_ExpensesOverAssets

0.50%

1 year

rr_ExpenseExampleYear01

$ 51

3 years

rr_ExpenseExampleYear03

$ 160

[1] Based on estimated amounts for the current fiscal year.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Flex Large Cap Growth Fund PRO-05 | Fidelity Flex Large Cap Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity Flex℠ Large Cap Growth Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks long-term growth of capital.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 55% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

55.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. This example does not include any fees paid at the fee-based account or plan level. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with large market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 1000^® Index or the S&P 500^® Index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance. The performance shown does not reflect the impact of any fees paid at the fee-based account or plan level.

Visit www.401k.com and log in for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.401k.com and log in</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	8.53%	June 30, 2018
Lowest Quarter Return	-17.56%	December 31, 2018
Year-to-Date Return	21.41%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Flex Large Cap Growth Fund PRO-05 | Fidelity Flex Large Cap Growth Fund | Fidelity Flex Large Cap Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

none

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

Total annual operating expenses

rr_ExpensesOverAssets

none

^[1]

1 year

rr_ExpenseExampleYear01

none

3 years

rr_ExpenseExampleYear03

none

5 years

rr_ExpenseExampleYear05

none

10 years

rr_ExpenseExampleYear10

none

2018

rr_AnnualReturn2018

(0.80%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

21.41%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2018

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

8.53%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(17.56%)

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 08, 2017

07.31 Fidelity Flex Large Cap Growth Fund PRO-05 | Fidelity Flex Large Cap Growth Fund | Return Before Taxes | Fidelity Flex Large Cap Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Flex Large Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(0.80%)

Since Inception

rr_AverageAnnualReturnSinceInception

12.61%

^[2]

07.31 Fidelity Flex Large Cap Growth Fund PRO-05 | Fidelity Flex Large Cap Growth Fund | After Taxes on Distributions | Fidelity Flex Large Cap Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Flex Large Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(1.78%)

Since Inception

rr_AverageAnnualReturnSinceInception

11.85%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 08, 2017

07.31 Fidelity Flex Large Cap Growth Fund PRO-05 | Fidelity Flex Large Cap Growth Fund | After Taxes on Distributions and Sales | Fidelity Flex Large Cap Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Flex Large Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

none

Since Inception

rr_AverageAnnualReturnSinceInception

9.59%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 08, 2017

07.31 Fidelity Flex Large Cap Growth Fund PRO-05 | Fidelity Flex Large Cap Growth Fund | Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(1.51%)

Since Inception

rr_AverageAnnualReturnSinceInception

9.87%

^[2]

[1] The fund is available only to certain fee-based accounts offered by Fidelity. Managed account clients, retirement plans, plan sponsors and/or plan participants pay a wrap fee that covers investment advisory and administrative services.

[2] From March 8, 2017

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Dividend Growth Fund K PRO-06 | Fidelity® Dividend Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Dividend Growth Fund</b>/K</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 101% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

101.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in equity securities.

• Normally investing primarily in common stocks.

• Normally investing primarily in companies that pay dividends or that Fidelity Management & Research Company (FMR) believes have the potential to pay dividends in the future.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.401k.com and log in </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	28.17%	June 30, 2009
Lowest Quarter Return	-20.90%	September 30, 2011
Year-to-Date Return	15.90%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

For the periods ended December 31, 2018

07.31 Fidelity Dividend Growth Fund K PRO-06 | Fidelity® Dividend Growth Fund | Fidelity Dividend Growth Fund-Class K

Risk/Return:

rr_RiskReturnAbstract

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.33%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.07%

Total annual operating expenses

rr_ExpensesOverAssets

0.40%

1 year

rr_ExpenseExampleYear01

$ 41

3 years

rr_ExpenseExampleYear03

128

5 years

rr_ExpenseExampleYear05

224

10 years

rr_ExpenseExampleYear10

$ 505

2009

rr_AnnualReturn2009

51.32%

2010

rr_AnnualReturn2010

21.43%

2011

rr_AnnualReturn2011

(8.34%)

2012

rr_AnnualReturn2012

18.88%

2013

rr_AnnualReturn2013

31.78%

2014

rr_AnnualReturn2014

11.99%

2015

rr_AnnualReturn2015

(0.51%)

2016

rr_AnnualReturn2016

8.19%

2017

rr_AnnualReturn2017

20.25%

2018

rr_AnnualReturn2018

(7.08%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

15.90%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

28.17%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(20.90%)

07.31 Fidelity Dividend Growth Fund K PRO-06 | Fidelity® Dividend Growth Fund | Return Before Taxes | Fidelity Dividend Growth Fund-Class K

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Dividend Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class K</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(7.08%)

Past 5 years

rr_AverageAnnualReturnYear05

6.14%

Past 10 years

rr_AverageAnnualReturnYear10

13.52%

07.31 Fidelity Dividend Growth Fund K PRO-06 | Fidelity® Dividend Growth Fund | S&P 500® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.38%)

Past 5 years

rr_AverageAnnualReturnYear05

8.49%

Past 10 years

rr_AverageAnnualReturnYear10

13.12%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 | Fidelity® Series Small Cap Opportunities Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Series Small Cap Opportunities Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 59% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

59.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in domestic and foreign issuers.

• Allocating the fund's assets across different market sectors (at present, communication services, consumer discretionary, consumer staples, energy, financials, health care, industrials, information technology, materials, real estate, and utilities), using different Fidelity managers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.fidelity.com</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	25.60%	June 30, 2009
Lowest Quarter Return	-21.59%	September 30, 2011
Year-to-Date Return	20.80%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 | Fidelity® Series Small Cap Opportunities Fund | Fidelity Series Small Cap Opportunities Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

none

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

Total annual operating expenses

rr_ExpensesOverAssets

none

1 year

rr_ExpenseExampleYear01

none

3 years

rr_ExpenseExampleYear03

none

5 years

rr_ExpenseExampleYear05

none

10 years

rr_ExpenseExampleYear10

none

2009

rr_AnnualReturn2009

46.51%

2010

rr_AnnualReturn2010

32.91%

2011

rr_AnnualReturn2011

(2.90%)

2012

rr_AnnualReturn2012

11.89%

2013

rr_AnnualReturn2013

35.51%

2014

rr_AnnualReturn2014

2.27%

2015

rr_AnnualReturn2015

(0.55%)

2016

rr_AnnualReturn2016

15.18%

2017

rr_AnnualReturn2017

12.02%

2018

rr_AnnualReturn2018

(7.63%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

20.80%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

25.60%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(21.59%)

07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 | Fidelity® Series Small Cap Opportunities Fund | Return Before Taxes | Fidelity Series Small Cap Opportunities Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Series Small Cap Opportunities Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(7.63%)

Past 5 years

rr_AverageAnnualReturnYear05

3.92%

Past 10 years

rr_AverageAnnualReturnYear10

13.27%

07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 | Fidelity® Series Small Cap Opportunities Fund | After Taxes on Distributions | Fidelity Series Small Cap Opportunities Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Series Small Cap Opportunities Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(10.48%)

Past 5 years

rr_AverageAnnualReturnYear05

2.12%

Past 10 years

rr_AverageAnnualReturnYear10

11.85%

07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 | Fidelity® Series Small Cap Opportunities Fund | After Taxes on Distributions and Sales | Fidelity Series Small Cap Opportunities Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Series Small Cap Opportunities Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(2.59%)

Past 5 years

rr_AverageAnnualReturnYear05

2.97%

Past 10 years

rr_AverageAnnualReturnYear10

11.00%

07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 | Fidelity® Series Small Cap Opportunities Fund | Russell 2000® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(11.01%)

Past 5 years

rr_AverageAnnualReturnYear05

4.41%

Past 10 years

rr_AverageAnnualReturnYear10

11.97%

XML

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Growth Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Blue Chip Growth Fund</b>/Fidelity® Blue Chip Growth Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks growth of capital over the long term.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Blue Chip Growth Fund}	07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 Fidelity® Blue Chip Growth Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Blue Chip Growth Fund}	07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 Fidelity® Blue Chip Growth Fund Fidelity Blue Chip Growth Fund-Retail Class
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.64%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.16%
Total annual operating expenses	0.80%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Blue Chip Growth Fund}	07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 Fidelity® Blue Chip Growth Fund Fidelity Blue Chip Growth Fund-Retail Class USD ($)
1 year	$ 82
3 years	255
5 years	444
10 years	$ 990

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 45% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	20.46%	September 30, 2009
Lowest Quarter Return	-16.00%	December 31, 2018
Year-to-Date Return	20.25%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Blue Chip Growth Fund} - 07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 - Fidelity® Blue Chip Growth Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Blue Chip Growth Fund-Retail Class | Return Before Taxes	1.07%	11.22%	16.80%
Fidelity Blue Chip Growth Fund-Retail Class | After Taxes on Distributions	(0.21%)	9.92%	15.80%
Fidelity Blue Chip Growth Fund-Retail Class | After Taxes on Distributions and Sales	1.77%	8.76%	14.17%
Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)	(1.51%)	10.40%	15.29%

XML

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Small Cap Growth Fund</b>/Fidelity Advisor® Small Cap Growth Fund A, M, C, I, Z</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund. In addition to the fees and expenses described below, your broker may also require you to pay brokerage commissions on purchases and sales of certain share classes of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity^® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 29 of the prospectus. Different intermediaries may provide additional waivers or reductions of the sales charge. Please see “Sales Charge Waiver Policies Applied by Certain Intermediaries” in the “Appendix” section of the prospectus.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(fees paid directly from your investment)</p>

Shareholder Fees {- Fidelity® Small Cap Growth Fund} - 07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 - Fidelity® Small Cap Growth Fund	Fidelity Small Cap Growth Fund-Class A		Fidelity Small Cap Growth Fund-Class M		Fidelity Small Cap Growth Fund-Class C		Fidelity Small Cap Growth Fund - Class I	Fidelity Small Cap Growth Fund-Class Z
Maximum sales charge (load) on purchases (as a % of offering price)	5.75%		3.50%		none		none	none
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)	none	[1]	none	[1]	1.00%	[2]	none	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Small Cap Growth Fund} - 07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 - Fidelity® Small Cap Growth Fund	Fidelity Small Cap Growth Fund-Class A	Fidelity Small Cap Growth Fund-Class M	Fidelity Small Cap Growth Fund-Class C	Fidelity Small Cap Growth Fund - Class I		Fidelity Small Cap Growth Fund-Class Z
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.84%	0.84%	0.84%	0.84%		0.84%
Distribution and/or Service (12b-1) fees	0.25%	0.50%	1.00%	none		none
Other expenses	0.24%	0.26%	0.25%	0.23%		0.09%
Total annual operating expenses	1.33%	1.60%	2.09%	1.07%	[1]	0.93%	[1]

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Small Cap Growth Fund} - 07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 - Fidelity® Small Cap Growth Fund - USD ($)	Fidelity Small Cap Growth Fund-Class A	Fidelity Small Cap Growth Fund-Class M	Fidelity Small Cap Growth Fund-Class C	Fidelity Small Cap Growth Fund - Class I	Fidelity Small Cap Growth Fund-Class Z
1 year	$ 703	$ 507	$ 312	$ 109	$ 95
3 years	972	837	655	340	296
5 years	1,262	1,190	1,124	590	515
10 years	$ 2,084	$ 2,184	$ 2,421	$ 1,306	$ 1,143

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Hold Shares</p>

Expense Example, No Redemption {- Fidelity® Small Cap Growth Fund} - 07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 - Fidelity® Small Cap Growth Fund - USD ($)	Fidelity Small Cap Growth Fund-Class A	Fidelity Small Cap Growth Fund-Class M	Fidelity Small Cap Growth Fund-Class C	Fidelity Small Cap Growth Fund - Class I	Fidelity Small Cap Growth Fund-Class Z
1 Year	$ 703	$ 507	$ 212	$ 109	$ 95
3 Years	972	837	655	340	296
5 Years	1,262	1,190	1,124	590	515
10 Years	$ 2,084	$ 2,184	$ 2,421	$ 1,306	$ 1,143

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 91% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit institutional.fidelity.com for more recent performance information.

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	23.91%	June 30, 2009
Lowest Quarter Return	-22.81%	December 31, 2018
Year-to-Date Return	26.16%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Small Cap Growth Fund} - 07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 - Fidelity® Small Cap Growth Fund	Past 1 year	Past 5 years	Past 10 years	Since Inception	[1]	Inception Date
Fidelity Small Cap Growth Fund-Class A | Return Before Taxes	(10.34%)	6.87%	14.71%
Fidelity Small Cap Growth Fund-Class A | After Taxes on Distributions	(13.11%)	5.14%	13.09%
Fidelity Small Cap Growth Fund-Class A | After Taxes on Distributions and Sales	(4.31%)	5.19%	12.08%
Fidelity Small Cap Growth Fund-Class M | Return Before Taxes	(8.44%)	7.08%	14.68%
Fidelity Small Cap Growth Fund-Class C | Return Before Taxes	(6.41%)	7.31%	14.52%
Fidelity Small Cap Growth Fund - Class I | Return Before Taxes	(4.58%)	8.46%	15.73%
Fidelity Small Cap Growth Fund-Class Z | Return Before Taxes	(4.46%)			9.55%		Feb. 01, 2017
Russell 2000® Growth Index(reflects no deduction for fees, expenses, or taxes)	(9.31%)	5.13%	13.52%

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund-Class A

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge CDSC of 1.00% or 0.25%, respectively.

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund-Class M

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge CDSC of 1.00% or 0.25%, respectively.

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund-Class C

On Class C shares redeemed less than one year after purchase

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund - Class I

Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus because of acquired fund fees and expenses. For the period, acquired fund fees and expenses are less than 0.01% and are included in other expenses.

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund-Class Z

Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus because of acquired fund fees and expenses. For the period, acquired fund fees and expenses are less than 0.01% and are included in other expenses.

[1] Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge CDSC of 1.00% or 0.25%, respectively.

[2] On Class C shares redeemed less than one year after purchase

[1] Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus because of acquired fund fees and expenses. For the period, acquired fund fees and expenses are less than 0.01% and are included in other expenses.

[1] Since inception February 1, 2017.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity OTC Portfolio Retail PRO-05 | Fidelity® OTC Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® OTC Portfolio</b>/Fidelity® OTC Portfolio</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 34% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

34.00%

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees

<font style="FONT-FAMILY: Times New Roman" size="3">Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus because of acquired fund fees and expenses. For the period, acquired fund fees and expenses are less than 0.01% and are included in other expenses.</font>

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities principally traded on NASDAQ^® or an over-the-counter (OTC) market, which has more small and medium-sized companies than other markets.

• Investing more than 25% of total assets in the technology sector.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Strategy Portfolio Concentration [Text]

rr_StrategyPortfolioConcentration

<font style="FONT-FAMILY: Times New Roman" size="3">Investing more than 25% of total assets in the technology sector.</font>

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Technology Industry Concentration. The technology industries can be significantly affected by obsolescence of existing technology, short product cycles, falling prices and profits, competition from new market entrants, and general economic conditions.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. The value of securities of smaller issuers can be more volatile than that of larger issuers.

In addition, the fund is classified as non-diversified under the Investment Company Act of 1940, which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

<font style="FONT-FAMILY: Times New Roman" size="3">In addition, the fund is classified as non-diversified under the Investment Company Act of 1940, which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.fidelity.com </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	24.53%	June 30, 2009
Lowest Quarter Return	-19.90%	December 31, 2018
Year-to-Date Return	22.01%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity OTC Portfolio Retail PRO-05 | Fidelity® OTC Portfolio | Fidelity OTC Portfolio-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.73%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.16%

Total annual operating expenses

rr_ExpensesOverAssets

0.89%

^[1]

1 year

rr_ExpenseExampleYear01

$ 91

3 years

rr_ExpenseExampleYear03

284

5 years

rr_ExpenseExampleYear05

493

10 years

rr_ExpenseExampleYear10

$ 1,096

2009

rr_AnnualReturn2009

62.24%

2010

rr_AnnualReturn2010

20.14%

2011

rr_AnnualReturn2011

(0.42%)

2012

rr_AnnualReturn2012

11.29%

2013

rr_AnnualReturn2013

46.50%

2014

rr_AnnualReturn2014

16.49%

2015

rr_AnnualReturn2015

10.92%

2016

rr_AnnualReturn2016

3.11%

2017

rr_AnnualReturn2017

38.59%

2018

rr_AnnualReturn2018

(3.21%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

22.01%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

24.53%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(19.90%)

07.31 Fidelity OTC Portfolio Retail PRO-05 | Fidelity® OTC Portfolio | Return Before Taxes | Fidelity OTC Portfolio-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® OTC Portfolio

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(3.21%)

Past 5 years

rr_AverageAnnualReturnYear05

12.31%

Past 10 years

rr_AverageAnnualReturnYear10

18.92%

07.31 Fidelity OTC Portfolio Retail PRO-05 | Fidelity® OTC Portfolio | After Taxes on Distributions | Fidelity OTC Portfolio-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® OTC Portfolio

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.71%)

Past 5 years

rr_AverageAnnualReturnYear05

10.28%

Past 10 years

rr_AverageAnnualReturnYear10

17.39%

07.31 Fidelity OTC Portfolio Retail PRO-05 | Fidelity® OTC Portfolio | After Taxes on Distributions and Sales | Fidelity OTC Portfolio-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® OTC Portfolio

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(0.53%)

Past 5 years

rr_AverageAnnualReturnYear05

9.27%

Past 10 years

rr_AverageAnnualReturnYear10

15.77%

07.31 Fidelity OTC Portfolio Retail PRO-05 | Fidelity® OTC Portfolio | Nasdaq Composite Index®(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(2.84%)

Past 5 years

rr_AverageAnnualReturnYear05

10.97%

Past 10 years

rr_AverageAnnualReturnYear10

16.76%

[1] Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus because of acquired fund fees and expenses. For the period, acquired fund fees and expenses are less than 0.01% and are included in other expenses.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity OTC Portfolio K PRO-05 | Fidelity® OTC Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® OTC Portfolio</b>/K</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 34% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

34.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities principally traded on NASDAQ^® or an over-the-counter (OTC) market, which has more small and medium-sized companies than other markets.

• Investing more than 25% of total assets in the technology sector.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Strategy Portfolio Concentration [Text]

rr_StrategyPortfolioConcentration

<font style="FONT-FAMILY: Times New Roman" size="3">Investing more than 25% of total assets in the technology sector.</font>

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Technology Industry Concentration. The technology industries can be significantly affected by obsolescence of existing technology, short product cycles, falling prices and profits, competition from new market entrants, and general economic conditions.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. The value of securities of smaller issuers can be more volatile than that of larger issuers.

In addition, the fund is classified as non-diversified under the Investment Company Act of 1940, which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

<font style="FONT-FAMILY: Times New Roman" size="3">In addition, the fund is classified as non-diversified under the Investment Company Act of 1940, which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.401k.com and log in </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	24.55%	June 30, 2009
Lowest Quarter Return	-19.85%	December 31, 2018
Year-to-Date Return	21.98%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

For the periods ended December 31, 2018

07.31 Fidelity OTC Portfolio K PRO-05 | Fidelity® OTC Portfolio | Fidelity OTC Portfolio-Class K

Risk/Return:

rr_RiskReturnAbstract

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.73%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.06%

Total annual operating expenses

rr_ExpensesOverAssets

0.79%

1 year

rr_ExpenseExampleYear01

$ 81

3 years

rr_ExpenseExampleYear03

252

5 years

rr_ExpenseExampleYear05

439

10 years

rr_ExpenseExampleYear10

$ 978

2009

rr_AnnualReturn2009

62.60%

2010

rr_AnnualReturn2010

20.34%

2011

rr_AnnualReturn2011

(0.29%)

2012

rr_AnnualReturn2012

11.45%

2013

rr_AnnualReturn2013

46.70%

2014

rr_AnnualReturn2014

16.62%

2015

rr_AnnualReturn2015

11.05%

2016

rr_AnnualReturn2016

3.23%

2017

rr_AnnualReturn2017

38.75%

2018

rr_AnnualReturn2018

(3.10%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

21.98%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

24.55%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(19.85%)

07.31 Fidelity OTC Portfolio K PRO-05 | Fidelity® OTC Portfolio | Return Before Taxes | Fidelity OTC Portfolio-Class K

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® OTC Portfolio

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class K</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(3.10%)

Past 5 years

rr_AverageAnnualReturnYear05

12.44%

Past 10 years

rr_AverageAnnualReturnYear10

19.08%

07.31 Fidelity OTC Portfolio K PRO-05 | Fidelity® OTC Portfolio | Nasdaq Composite Index®(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(2.84%)

Past 5 years

rr_AverageAnnualReturnYear05

10.97%

Past 10 years

rr_AverageAnnualReturnYear10

16.76%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Small Cap Growth K6 Fund PRO-04 | Fidelity Small Cap Growth K6 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Small Cap Growth K6 Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 108% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

108.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.401k.com and log in </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	7.97%	September 30, 2018
Lowest Quarter Return	-22.41%	December 31, 2018
Year-to-Date Return	26.22%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

For the periods ended December 31, 2018

07.31 Fidelity Small Cap Growth K6 Fund PRO-04 | Fidelity Small Cap Growth K6 Fund | Fidelity Small Cap Growth K6 Fund

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

0.60%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

Total annual operating expenses

rr_ExpensesOverAssets

0.60%

1 year

rr_ExpenseExampleYear01

$ 61

3 years

rr_ExpenseExampleYear03

192

5 years

rr_ExpenseExampleYear05

335

10 years

rr_ExpenseExampleYear10

$ 750

2018

rr_AnnualReturn2018

(4.61%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

26.22%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2018

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

7.97%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(22.41%)

Inception Date

rr_AverageAnnualReturnInceptionDate

May 25, 2017

07.31 Fidelity Small Cap Growth K6 Fund PRO-04 | Fidelity Small Cap Growth K6 Fund | Return Before Taxes | Fidelity Small Cap Growth K6 Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Growth K6 Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Fidelity® Small Cap Growth K6 Fund</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.61%)

Since Inception

rr_AverageAnnualReturnSinceInception

6.64%

^[1]

07.31 Fidelity Small Cap Growth K6 Fund PRO-04 | Fidelity Small Cap Growth K6 Fund | Russell 2000® Growth Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(9.31%)

Since Inception

rr_AverageAnnualReturnSinceInception

2.13%

^[1]

[1] From May 25, 2017

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Small Cap Value Fund</b>/Fidelity Advisor® Small Cap Value Fund A, M, C, I, Z</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund. In addition to the fees and expenses described below, your broker may also require you to pay brokerage commissions on purchases and sales of certain share classes of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity^® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 28 of the prospectus. Different intermediaries may provide additional waivers or reductions of the sales charge. Please see “Sales Charge Waiver Policies Applied by Certain Intermediaries” in the “Appendix” section of the prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(fees paid directly from your investment)</p>

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 79% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

79.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

<font style="FONT-FAMILY: Times New Roman" size="3">You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 28 of the prospectus.</font>

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Hold Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in securities of companies that Fidelity Management & Research Company (FMR) believes are undervalued in the marketplace in relation to factors such as assets, sales, earnings, growth potential, or cash flow, or in relation to securities of other companies in the same industry (stocks of these companies are often called "value" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Value" Investing. "Value" stocks can perform differently from the market as a whole and other types of stocks and can continue to be undervalued by the market for long periods of time.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit institutional.fidelity.com for more recent performance information.

Performance history will be available for Class Z after Class Z has been in operation for one calendar year.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3"> institutional.fidelity.com</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Narrative [Text Block]

rr_BarChartNarrativeTextBlock

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

<font style="FONT-FAMILY: Times New Roman" size="3">The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.</font>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	25.25%	June 30, 2009
Lowest Quarter Return	-20.24%	September 30, 2011
Year-to-Date Return	12.61%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

<font style="FONT-FAMILY: Times New Roman" size="3">Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges.</font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary.</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Fidelity Advisor Small Cap Value Fund: Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

5.75%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.43%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.24%

Total annual operating expenses

rr_ExpensesOverAssets

0.92%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

$ 663

3 years

rr_ExpenseExampleYear03

851

5 years

rr_ExpenseExampleYear05

1,055

10 years

rr_ExpenseExampleYear10

1,641

1 Year

rr_ExpenseExampleNoRedemptionYear01

663

3 Years

rr_ExpenseExampleNoRedemptionYear03

851

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,055

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,641

2009

rr_AnnualReturn2009

36.46%

2010

rr_AnnualReturn2010

24.77%

2011

rr_AnnualReturn2011

(3.98%)

2012

rr_AnnualReturn2012

19.80%

2013

rr_AnnualReturn2013

36.72%

2014

rr_AnnualReturn2014

6.30%

2015

rr_AnnualReturn2015

(1.89%)

2016

rr_AnnualReturn2016

21.03%

2017

rr_AnnualReturn2017

11.98%

2018

rr_AnnualReturn2018

(15.21%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

12.61%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

25.25%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(20.24%)

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Fidelity Advisor Small Cap Value Fund: Class M

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

3.50%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.43%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.50%

Other expenses

rr_OtherExpensesOverAssets

0.24%

Total annual operating expenses

rr_ExpensesOverAssets

1.17%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

$ 465

3 years

rr_ExpenseExampleYear03

709

5 years

rr_ExpenseExampleYear05

971

10 years

rr_ExpenseExampleYear10

1,721

1 Year

rr_ExpenseExampleNoRedemptionYear01

465

3 Years

rr_ExpenseExampleNoRedemptionYear03

709

5 Years

rr_ExpenseExampleNoRedemptionYear05

971

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,721

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Fidelity Advisor Small Cap Value Fund: Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[2]

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.43%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.25%

Total annual operating expenses

rr_ExpensesOverAssets

1.68%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

On Class C shares redeemed less than one year after purchase.

1 year

rr_ExpenseExampleYear01

$ 271

3 years

rr_ExpenseExampleYear03

530

5 years

rr_ExpenseExampleYear05

913

10 years

rr_ExpenseExampleYear10

1,987

1 Year

rr_ExpenseExampleNoRedemptionYear01

171

3 Years

rr_ExpenseExampleNoRedemptionYear03

530

5 Years

rr_ExpenseExampleNoRedemptionYear05

913

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,987

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Fidelity Advisor Small Cap Value Fund: Class I

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.43%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.23%

Total annual operating expenses

rr_ExpensesOverAssets

0.66%

1 year

rr_ExpenseExampleYear01

$ 67

3 years

rr_ExpenseExampleYear03

211

5 years

rr_ExpenseExampleYear05

368

10 years

rr_ExpenseExampleYear10

822

1 Year

rr_ExpenseExampleNoRedemptionYear01

67

3 Years

rr_ExpenseExampleNoRedemptionYear03

211

5 Years

rr_ExpenseExampleNoRedemptionYear05

368

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 822

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Fidelity Advisor Small Cap Value Fund: Class Z

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.43%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.09%

Total annual operating expenses

rr_ExpensesOverAssets

0.52%

1 year

rr_ExpenseExampleYear01

$ 53

3 years

rr_ExpenseExampleYear03

167

5 years

rr_ExpenseExampleYear05

291

10 years

rr_ExpenseExampleYear10

653

1 Year

rr_ExpenseExampleNoRedemptionYear01

53

3 Years

rr_ExpenseExampleNoRedemptionYear03

167

5 Years

rr_ExpenseExampleNoRedemptionYear05

291

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 653

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Return Before Taxes | Fidelity Advisor Small Cap Value Fund: Class A

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class A - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(20.09%)

Past 5 years

rr_AverageAnnualReturnYear05

2.47%

Past 10 years

rr_AverageAnnualReturnYear10

11.70%

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Return Before Taxes | Fidelity Advisor Small Cap Value Fund: Class M

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class M - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(18.38%)

Past 5 years

rr_AverageAnnualReturnYear05

2.70%

Past 10 years

rr_AverageAnnualReturnYear10

11.68%

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Return Before Taxes | Fidelity Advisor Small Cap Value Fund: Class C

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class C - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(16.52%)

Past 5 years

rr_AverageAnnualReturnYear05

2.88%

Past 10 years

rr_AverageAnnualReturnYear10

11.50%

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Return Before Taxes | Fidelity Advisor Small Cap Value Fund: Class I

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class I - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(14.97%)

Past 5 years

rr_AverageAnnualReturnYear05

3.96%

Past 10 years

rr_AverageAnnualReturnYear10

12.67%

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | After Taxes on Distributions | Fidelity Advisor Small Cap Value Fund: Class A

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(24.87%)

Past 5 years

rr_AverageAnnualReturnYear05

(0.36%)

Past 10 years

rr_AverageAnnualReturnYear10

9.70%

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | After Taxes on Distributions and Sales | Fidelity Advisor Small Cap Value Fund: Class A

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(7.41%)

Past 5 years

rr_AverageAnnualReturnYear05

2.08%

Past 10 years

rr_AverageAnnualReturnYear10

9.75%

07.31 Fidelity Small Cap Value Fund AMCIZ PRO-08 | Fidelity Small Cap Value Fund | Russell 2000® Value Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(12.86%)

Past 5 years

rr_AverageAnnualReturnYear05

3.61%

Past 10 years

rr_AverageAnnualReturnYear10

10.40%

[1] Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

[2] On Class C shares redeemed less than one year after purchase.

XML

07.31 Fidelity Growth & Income Portfolio Retail PRO-04 | Fidelity® Growth & Income Portfolio

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Growth & Income Portfolio</b>/Fidelity® Growth & Income Portfolio</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks high total return through a combination of current income and capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Growth & Income Portfolio}	07.31 Fidelity Growth & Income Portfolio Retail PRO-04 Fidelity® Growth & Income Portfolio USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Growth & Income Portfolio}	07.31 Fidelity Growth & Income Portfolio Retail PRO-04 Fidelity® Growth & Income Portfolio Fidelity® Growth & Income Portfolio
Management fee	0.44%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.17%
Total annual operating expenses	0.61%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Growth & Income Portfolio}	07.31 Fidelity Growth & Income Portfolio Retail PRO-04 Fidelity® Growth & Income Portfolio Fidelity® Growth & Income Portfolio USD ($)
1 year	$ 62
3 years	195
5 years	340
10 years	$ 762

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 36% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing a majority of assets in common stocks with a focus on those that pay current dividends and show potential for capital appreciation.

• Potentially investing in bonds, including lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds), as well as stocks that are not currently paying dividends, but offer prospects for future income or capital appreciation.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	15.62%	June 30, 2009
Lowest Quarter Return	-15.05%	December 31, 2018
Year-to-Date Return	16.12%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Growth & Income Portfolio} - 07.31 Fidelity Growth & Income Portfolio Retail PRO-04 - Fidelity® Growth & Income Portfolio	Past 1 year	Past 5 years	Past 10 years
Fidelity® Growth & Income Portfolio | Return Before Taxes	(8.91%)	5.92%	11.71%
Fidelity® Growth & Income Portfolio | After Taxes on Distributions	(9.57%)	5.39%	11.30%
Fidelity® Growth & Income Portfolio | After Taxes on Distributions and Sales	(4.73%)	4.60%	9.75%
S&P 500® Index(reflects no deduction for fees, expenses, or taxes)	(4.38%)	8.49%	13.12%

XML

07.31 Fidelity Growth & Income Portfolio K PRO-05 | Fidelity® Growth & Income Portfolio

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Growth & Income Portfolio</b>/K</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks high total return through a combination of current income and capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Growth & Income Portfolio}	07.31 Fidelity Growth & Income Portfolio K PRO-05 Fidelity® Growth & Income Portfolio USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Growth & Income Portfolio}	07.31 Fidelity Growth & Income Portfolio K PRO-05 Fidelity® Growth & Income Portfolio Fidelity® Growth & Income Portfolio Class K
Management fee	0.44%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.07%
Total annual operating expenses	0.51%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Growth & Income Portfolio}	07.31 Fidelity Growth & Income Portfolio K PRO-05 Fidelity® Growth & Income Portfolio Fidelity® Growth & Income Portfolio Class K USD ($)
1 year	$ 52
3 years	164
5 years	285
10 years	$ 640

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 36% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing a majority of assets in common stocks with a focus on those that pay current dividends and show potential for capital appreciation.

• Potentially investing in bonds, including lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds), as well as stocks that are not currently paying dividends, but offer prospects for future income or capital appreciation.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	15.60%	June 30, 2009
Lowest Quarter Return	-15.03%	December 31, 2018
Year-to-Date Return	16.19%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Growth & Income Portfolio} - 07.31 Fidelity Growth & Income Portfolio K PRO-05 - Fidelity® Growth & Income Portfolio	Past 1 year	Past 5 years	Past 10 years
Fidelity® Growth & Income Portfolio Class K | Return Before Taxes	(8.85%)	6.03%	11.88%
S&P 500® Index(reflects no deduction for fees, expenses, or taxes)	(4.38%)	8.49%	13.12%

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FIDELITY SECURITIES FUND
Prospectus Date	rr_ProspectusDate	Sep. 28, 2019
Document Creation Date	dei_DocumentCreationDate	Sep. 26, 2019

XML

07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 | Fidelity® Leveraged Company Stock Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Leveraged Company Stock Fund</b>/Fidelity® Leveraged Company Stock Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Leveraged Company Stock Fund}	07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 Fidelity® Leveraged Company Stock Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Leveraged Company Stock Fund}	07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 Fidelity® Leveraged Company Stock Fund Fidelity Leveraged Company Stock Fund-Retail Class
Management fee	0.59%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.19%
Total annual operating expenses	0.78%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Leveraged Company Stock Fund}	07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 Fidelity® Leveraged Company Stock Fund Fidelity Leveraged Company Stock Fund-Retail Class USD ($)
1 year	$ 80
3 years	249
5 years	433
10 years	$ 966

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 53% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing at least 80% of assets in stocks.

• Normally investing primarily in common stocks of leveraged companies (companies that issue lower-quality debt and other companies with leveraged capital structures).

• Potentially investing in lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

• Highly Leveraged Company Exposure. Leverage can magnify the impact of adverse issuer, political, regulatory, market, or economic developments on a company.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	38.14%	June 30, 2009
Lowest Quarter Return	-26.60%	September 30, 2011
Year-to-Date Return	22.14%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Effective October 1, 2019, the fund's benchmarks will change from the S&P 500^® Index and the Credit Suisse Leveraged Equity Index to the Russell Mid Cap Index and the Fidelity U.S. Leveraged Stock Linked Index℠, respectively.

Average Annual Total Returns{- Fidelity® Leveraged Company Stock Fund} - 07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 - Fidelity® Leveraged Company Stock Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Leveraged Company Stock Fund-Retail Class | Return Before Taxes	(16.42%)	1.48%	12.77%
Fidelity Leveraged Company Stock Fund-Retail Class | After Taxes on Distributions	(19.35%)	(1.55%)	11.00%
Fidelity Leveraged Company Stock Fund-Retail Class | After Taxes on Distributions and Sales	(6.94%)	1.32%	10.79%
S&P 500® Index(reflects no deduction for fees, expenses, or taxes)	(4.38%)	8.49%	13.12%
Credit Suisse Leveraged Equity Index(reflects no deduction for fees, expenses, or taxes)	(16.29%)	(0.83%)	10.07%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Series Real Estate Income Fund Series PRO-05 | Fidelity® Series Real Estate Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Series Real Estate Income Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks higher than average income. As a secondary objective, the fund also seeks capital growth.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

As a secondary objective, the fund also seeks capital growth.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 16% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

16.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in preferred and common stocks of real estate investment trusts (REITs); debt securities of real estate entities; and commercial and other mortgage-backed securities, with an emphasis on lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Normally investing at least 80% of assets in securities of companies principally engaged in the real estate industry and other real estate related investments.

• Investing in domestic and foreign issuers.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

Strategy Portfolio Concentration [Text]

rr_StrategyPortfolioConcentration

<font style="FONT-FAMILY: Times New Roman" size="3">Normally investing at least 80% of assets in securities of companies principally engaged in the real estate industry and other real estate related investments.</font>

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Real Estate Industry Concentration. Changes in real estate values or economic downturns can have a significant negative effect on issuers in the real estate industry. The value of securities of issuers in the real estate industry can be affected by changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, and the management skill and creditworthiness of the issuer.

• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments and can be difficult to resell.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.fidelity.com </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	5.69%	March 31, 2012
Lowest Quarter Return	-2.39%	December 31, 2018
Year-to-Date Return	10.33%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Series Real Estate Income Fund Series PRO-05 | Fidelity® Series Real Estate Income Fund | Fidelity Series Real Estate Income Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

none

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

Total annual operating expenses

rr_ExpensesOverAssets

none

1 year

rr_ExpenseExampleYear01

none

3 years

rr_ExpenseExampleYear03

none

5 years

rr_ExpenseExampleYear05

none

10 years

rr_ExpenseExampleYear10

none

2012

rr_AnnualReturn2012

17.21%

2013

rr_AnnualReturn2013

5.17%

2014

rr_AnnualReturn2014

10.77%

2015

rr_AnnualReturn2015

2.30%

2016

rr_AnnualReturn2016

8.31%

2017

rr_AnnualReturn2017

7.44%

2018

rr_AnnualReturn2018

0.67%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

10.33%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

5.69%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(2.39%)

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 20, 2011

07.31 Fidelity Series Real Estate Income Fund Series PRO-05 | Fidelity® Series Real Estate Income Fund | Return Before Taxes | Fidelity Series Real Estate Income Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Series Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

0.67%

Past 5 years

rr_AverageAnnualReturnYear05

5.83%

Since Inception

rr_AverageAnnualReturnSinceInception

7.59%

^[1]

07.31 Fidelity Series Real Estate Income Fund Series PRO-05 | Fidelity® Series Real Estate Income Fund | After Taxes on Distributions | Fidelity Series Real Estate Income Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Series Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(1.91%)

Past 5 years

rr_AverageAnnualReturnYear05

3.70%

Since Inception

rr_AverageAnnualReturnSinceInception

5.57%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 20, 2011

07.31 Fidelity Series Real Estate Income Fund Series PRO-05 | Fidelity® Series Real Estate Income Fund | After Taxes on Distributions and Sales | Fidelity Series Real Estate Income Fund-Default

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Series Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

0.65%

Past 5 years

rr_AverageAnnualReturnYear05

4.00%

Since Inception

rr_AverageAnnualReturnSinceInception

5.59%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 20, 2011

07.31 Fidelity Series Real Estate Income Fund Series PRO-05 | Fidelity® Series Real Estate Income Fund | S&P 500® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.38%)

Past 5 years

rr_AverageAnnualReturnYear05

8.49%

Since Inception

rr_AverageAnnualReturnSinceInception

12.92%

^[1]

07.31 Fidelity Series Real Estate Income Fund Series PRO-05 | Fidelity® Series Real Estate Income Fund | Fidelity Series Real Estate Income Composite Index℠(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(3.72%)

Past 5 years

rr_AverageAnnualReturnYear05

5.34%

Since Inception

rr_AverageAnnualReturnSinceInception

5.54%

^[1]

[1] From October 20, 2011

XML

07.31 Fidelity Blue Chip Growth Fund K PRO-05 | Fidelity® Blue Chip Growth Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Blue Chip Growth Fund</b>/K</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks growth of capital over the long term.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Blue Chip Growth Fund}	07.31 Fidelity Blue Chip Growth Fund K PRO-05 Fidelity® Blue Chip Growth Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Blue Chip Growth Fund}	07.31 Fidelity Blue Chip Growth Fund K PRO-05 Fidelity® Blue Chip Growth Fund Fidelity Blue Chip Growth Fund-Class K
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.64%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.06%
Total annual operating expenses	0.70%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Blue Chip Growth Fund}	07.31 Fidelity Blue Chip Growth Fund K PRO-05 Fidelity® Blue Chip Growth Fund Fidelity Blue Chip Growth Fund-Class K USD ($)
1 year	$ 72
3 years	224
5 years	390
10 years	$ 871

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 45% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	20.55%	September 30, 2009
Lowest Quarter Return	-15.99%	December 31, 2018
Year-to-Date Return	20.32%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Blue Chip Growth Fund} - 07.31 Fidelity Blue Chip Growth Fund K PRO-05 - Fidelity® Blue Chip Growth Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Blue Chip Growth Fund-Class K | Return Before Taxes	1.16%	11.34%	16.97%
Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)	(1.51%)	10.40%	15.29%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Blue Chip Growth Fund</b>/Fidelity® Blue Chip Growth Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks growth of capital over the long term.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 45% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

45.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.fidelity.com</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	20.46%	September 30, 2009
Lowest Quarter Return	-16.00%	December 31, 2018
Year-to-Date Return	20.25%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Growth Fund | Fidelity Blue Chip Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.64%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.16%

Total annual operating expenses

rr_ExpensesOverAssets

0.80%

1 year

rr_ExpenseExampleYear01

$ 82

3 years

rr_ExpenseExampleYear03

255

5 years

rr_ExpenseExampleYear05

444

10 years

rr_ExpenseExampleYear10

$ 990

2009

rr_AnnualReturn2009

44.96%

2010

rr_AnnualReturn2010

19.61%

2011

rr_AnnualReturn2011

(2.72%)

2012

rr_AnnualReturn2012

17.77%

2013

rr_AnnualReturn2013

39.84%

2014

rr_AnnualReturn2014

14.60%

2015

rr_AnnualReturn2015

6.28%

2016

rr_AnnualReturn2016

1.59%

2017

rr_AnnualReturn2017

36.06%

2018

rr_AnnualReturn2018

1.07%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

20.25%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

20.46%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(16.00%)

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Growth Fund | Return Before Taxes | Fidelity Blue Chip Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Blue Chip Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

1.07%

Past 5 years

rr_AverageAnnualReturnYear05

11.22%

Past 10 years

rr_AverageAnnualReturnYear10

16.80%

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Growth Fund | After Taxes on Distributions | Fidelity Blue Chip Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Blue Chip Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(0.21%)

Past 5 years

rr_AverageAnnualReturnYear05

9.92%

Past 10 years

rr_AverageAnnualReturnYear10

15.80%

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Growth Fund | After Taxes on Distributions and Sales | Fidelity Blue Chip Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Blue Chip Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

1.77%

Past 5 years

rr_AverageAnnualReturnYear05

8.76%

Past 10 years

rr_AverageAnnualReturnYear10

14.17%

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Growth Fund | Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(1.51%)

Past 5 years

rr_AverageAnnualReturnYear05

10.40%

Past 10 years

rr_AverageAnnualReturnYear10

15.29%

XML

07.31 Fidelity OTC Portfolio Retail PRO-05 | Fidelity® OTC Portfolio

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® OTC Portfolio</b>/Fidelity® OTC Portfolio</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® OTC Portfolio}	07.31 Fidelity OTC Portfolio Retail PRO-05 Fidelity® OTC Portfolio USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® OTC Portfolio}	07.31 Fidelity OTC Portfolio Retail PRO-05 Fidelity® OTC Portfolio Fidelity OTC Portfolio-Retail Class
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.73%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.16%
Total annual operating expenses	0.89%	[1]

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® OTC Portfolio}	07.31 Fidelity OTC Portfolio Retail PRO-05 Fidelity® OTC Portfolio Fidelity OTC Portfolio-Retail Class USD ($)
1 year	$ 91
3 years	284
5 years	493
10 years	$ 1,096

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 34% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities principally traded on NASDAQ^® or an over-the-counter (OTC) market, which has more small and medium-sized companies than other markets.

• Investing more than 25% of total assets in the technology sector.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Technology Industry Concentration. The technology industries can be significantly affected by obsolescence of existing technology, short product cycles, falling prices and profits, competition from new market entrants, and general economic conditions.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. The value of securities of smaller issuers can be more volatile than that of larger issuers.

In addition, the fund is classified as non-diversified under the Investment Company Act of 1940, which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	24.53%	June 30, 2009
Lowest Quarter Return	-19.90%	December 31, 2018
Year-to-Date Return	22.01%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® OTC Portfolio} - 07.31 Fidelity OTC Portfolio Retail PRO-05 - Fidelity® OTC Portfolio	Past 1 year	Past 5 years	Past 10 years
Fidelity OTC Portfolio-Retail Class | Return Before Taxes	(3.21%)	12.31%	18.92%
Fidelity OTC Portfolio-Retail Class | After Taxes on Distributions	(4.71%)	10.28%	17.39%
Fidelity OTC Portfolio-Retail Class | After Taxes on Distributions and Sales	(0.53%)	9.27%	15.77%
Nasdaq Composite Index®(reflects no deduction for fees, expenses, or taxes)	(2.84%)	10.97%	16.76%

[1] Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus because of acquired fund fees and expenses. For the period, acquired fund fees and expenses are less than 0.01% and are included in other expenses.

XML

07.31 Fidelity Dividend Growth Fund K PRO-06 | Fidelity® Dividend Growth Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Dividend Growth Fund</b>/K</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Dividend Growth Fund}	07.31 Fidelity Dividend Growth Fund K PRO-06 Fidelity® Dividend Growth Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Dividend Growth Fund}	07.31 Fidelity Dividend Growth Fund K PRO-06 Fidelity® Dividend Growth Fund Fidelity Dividend Growth Fund-Class K
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.33%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.07%
Total annual operating expenses	0.40%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Dividend Growth Fund}	07.31 Fidelity Dividend Growth Fund K PRO-06 Fidelity® Dividend Growth Fund Fidelity Dividend Growth Fund-Class K USD ($)
1 year	$ 41
3 years	128
5 years	224
10 years	$ 505

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 101% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing at least 80% of assets in equity securities.

• Normally investing primarily in common stocks.

• Normally investing primarily in companies that pay dividends or that Fidelity Management & Research Company (FMR) believes have the potential to pay dividends in the future.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	28.17%	June 30, 2009
Lowest Quarter Return	-20.90%	September 30, 2011
Year-to-Date Return	15.90%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Dividend Growth Fund} - 07.31 Fidelity Dividend Growth Fund K PRO-06 - Fidelity® Dividend Growth Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Dividend Growth Fund-Class K | Return Before Taxes	(7.08%)	6.14%	13.52%
S&P 500® Index(reflects no deduction for fees, expenses, or taxes)	(4.38%)	8.49%	13.12%

XML

07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 | Fidelity® Series Small Cap Opportunities Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Series Small Cap Opportunities Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Series Small Cap Opportunities Fund}	07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 Fidelity® Series Small Cap Opportunities Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Series Small Cap Opportunities Fund}	07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 Fidelity® Series Small Cap Opportunities Fund Fidelity Series Small Cap Opportunities Fund-Default
Management fee	none
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	none

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Series Small Cap Opportunities Fund}	07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 Fidelity® Series Small Cap Opportunities Fund Fidelity Series Small Cap Opportunities Fund-Default USD ($)
1 year	none
3 years	none
5 years	none
10 years	none

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 59% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in domestic and foreign issuers.

• Allocating the fund's assets across different market sectors (at present, communication services, consumer discretionary, consumer staples, energy, financials, health care, industrials, information technology, materials, real estate, and utilities), using different Fidelity managers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	25.60%	June 30, 2009
Lowest Quarter Return	-21.59%	September 30, 2011
Year-to-Date Return	20.80%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Series Small Cap Opportunities Fund} - 07.31 Fidelity Series Small Cap Opportunities Fund Series PRO-06 - Fidelity® Series Small Cap Opportunities Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Series Small Cap Opportunities Fund-Default | Return Before Taxes	(7.63%)	3.92%	13.27%
Fidelity Series Small Cap Opportunities Fund-Default | After Taxes on Distributions	(10.48%)	2.12%	11.85%
Fidelity Series Small Cap Opportunities Fund-Default | After Taxes on Distributions and Sales	(2.59%)	2.97%	11.00%
Russell 2000® Index(reflects no deduction for fees, expenses, or taxes)	(11.01%)	4.41%	11.97%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Growth & Income Portfolio Retail PRO-04 | Fidelity® Growth &amp; Income Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Growth & Income Portfolio</b>/Fidelity® Growth & Income Portfolio</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks high total return through a combination of current income and capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 36% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

36.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing a majority of assets in common stocks with a focus on those that pay current dividends and show potential for capital appreciation.

• Potentially investing in bonds, including lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds), as well as stocks that are not currently paying dividends, but offer prospects for future income or capital appreciation.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.fidelity.com</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	15.62%	June 30, 2009
Lowest Quarter Return	-15.05%	December 31, 2018
Year-to-Date Return	16.12%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Growth & Income Portfolio Retail PRO-04 | Fidelity® Growth &amp; Income Portfolio | Fidelity® Growth & Income Portfolio

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

0.44%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.17%

Total annual operating expenses

rr_ExpensesOverAssets

0.61%

1 year

rr_ExpenseExampleYear01

$ 62

3 years

rr_ExpenseExampleYear03

195

5 years

rr_ExpenseExampleYear05

340

10 years

rr_ExpenseExampleYear10

$ 762

2009

rr_AnnualReturn2009

23.05%

2010

rr_AnnualReturn2010

14.57%

2011

rr_AnnualReturn2011

1.39%

2012

rr_AnnualReturn2012

19.10%

2013

rr_AnnualReturn2013

33.40%

2014

rr_AnnualReturn2014

10.38%

2015

rr_AnnualReturn2015

(2.28%)

2016

rr_AnnualReturn2016

16.06%

2017

rr_AnnualReturn2017

16.88%

2018

rr_AnnualReturn2018

(8.91%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

16.12%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

15.62%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(15.05%)

07.31 Fidelity Growth & Income Portfolio Retail PRO-04 | Fidelity® Growth &amp; Income Portfolio | Return Before Taxes | Fidelity® Growth & Income Portfolio

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Growth & Income Portfolio

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(8.91%)

Past 5 years

rr_AverageAnnualReturnYear05

5.92%

Past 10 years

rr_AverageAnnualReturnYear10

11.71%

07.31 Fidelity Growth & Income Portfolio Retail PRO-04 | Fidelity® Growth &amp; Income Portfolio | After Taxes on Distributions | Fidelity® Growth & Income Portfolio

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Growth & Income Portfolio

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(9.57%)

Past 5 years

rr_AverageAnnualReturnYear05

5.39%

Past 10 years

rr_AverageAnnualReturnYear10

11.30%

07.31 Fidelity Growth & Income Portfolio Retail PRO-04 | Fidelity® Growth &amp; Income Portfolio | After Taxes on Distributions and Sales | Fidelity® Growth & Income Portfolio

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Growth & Income Portfolio

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.73%)

Past 5 years

rr_AverageAnnualReturnYear05

4.60%

Past 10 years

rr_AverageAnnualReturnYear10

9.75%

07.31 Fidelity Growth & Income Portfolio Retail PRO-04 | Fidelity® Growth &amp; Income Portfolio | S&P 500® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.38%)

Past 5 years

rr_AverageAnnualReturnYear05

8.49%

Past 10 years

rr_AverageAnnualReturnYear10

13.12%

XML

07.31 Fidelity Small Cap Growth K6 Fund PRO-04 | Fidelity Small Cap Growth K6 Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Small Cap Growth K6 Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity Small Cap Growth K6 Fund}	07.31 Fidelity Small Cap Growth K6 Fund PRO-04 Fidelity Small Cap Growth K6 Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity Small Cap Growth K6 Fund}	07.31 Fidelity Small Cap Growth K6 Fund PRO-04 Fidelity Small Cap Growth K6 Fund Fidelity Small Cap Growth K6 Fund
Management fee	0.60%
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	0.60%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity Small Cap Growth K6 Fund}	07.31 Fidelity Small Cap Growth K6 Fund PRO-04 Fidelity Small Cap Growth K6 Fund Fidelity Small Cap Growth K6 Fund USD ($)
1 year	$ 61
3 years	192
5 years	335
10 years	$ 750

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 108% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	7.97%	September 30, 2018
Lowest Quarter Return	-22.41%	December 31, 2018
Year-to-Date Return	26.22%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity Small Cap Growth K6 Fund} - 07.31 Fidelity Small Cap Growth K6 Fund PRO-04 - Fidelity Small Cap Growth K6 Fund	Past 1 year	Since Inception	[1]	Inception Date
Fidelity Small Cap Growth K6 Fund				May 25, 2017
Fidelity Small Cap Growth K6 Fund | Return Before Taxes	(4.61%)	6.64%
Russell 2000® Growth Index(reflects no deduction for fees, expenses, or taxes)	(9.31%)	2.13%

[1] From May 25, 2017

XML

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity® Small Cap Growth Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Small Cap Growth Fund</b>/Fidelity® Small Cap Growth Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Small Cap Growth Fund}	07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 Fidelity® Small Cap Growth Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Small Cap Growth Fund}	07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 Fidelity® Small Cap Growth Fund Fidelity Small Cap Growth Fund-Retail Class
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.84%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.21%
Total annual operating expenses	1.05%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Small Cap Growth Fund}	07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 Fidelity® Small Cap Growth Fund Fidelity Small Cap Growth Fund-Retail Class USD ($)
1 year	$ 107
3 years	334
5 years	579
10 years	$ 1,283

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 91% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	23.95%	June 30, 2009
Lowest Quarter Return	-22.73%	December 31, 2018
Year-to-Date Return	26.32%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Small Cap Growth Fund} - 07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 - Fidelity® Small Cap Growth Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Small Cap Growth Fund-Retail Class | Return Before Taxes	(4.58%)	8.46%	15.73%
Fidelity Small Cap Growth Fund-Retail Class | After Taxes on Distributions	(7.46%)	6.73%	14.11%
Fidelity Small Cap Growth Fund-Retail Class | After Taxes on Distributions and Sales	(0.85%)	6.44%	12.99%
Russell 2000® Growth Index(reflects no deduction for fees, expenses, or taxes)	(9.31%)	5.13%	13.52%

XML

07.31 Fidelity OTC Portfolio K PRO-05 | Fidelity® OTC Portfolio

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® OTC Portfolio</b>/K</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® OTC Portfolio}	07.31 Fidelity OTC Portfolio K PRO-05 Fidelity® OTC Portfolio USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® OTC Portfolio}	07.31 Fidelity OTC Portfolio K PRO-05 Fidelity® OTC Portfolio Fidelity OTC Portfolio-Class K
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.73%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.06%
Total annual operating expenses	0.79%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® OTC Portfolio}	07.31 Fidelity OTC Portfolio K PRO-05 Fidelity® OTC Portfolio Fidelity OTC Portfolio-Class K USD ($)
1 year	$ 81
3 years	252
5 years	439
10 years	$ 978

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 34% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities principally traded on NASDAQ^® or an over-the-counter (OTC) market, which has more small and medium-sized companies than other markets.

• Investing more than 25% of total assets in the technology sector.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Technology Industry Concentration. The technology industries can be significantly affected by obsolescence of existing technology, short product cycles, falling prices and profits, competition from new market entrants, and general economic conditions.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. The value of securities of smaller issuers can be more volatile than that of larger issuers.

In addition, the fund is classified as non-diversified under the Investment Company Act of 1940, which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	24.55%	June 30, 2009
Lowest Quarter Return	-19.85%	December 31, 2018
Year-to-Date Return	21.98%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® OTC Portfolio} - 07.31 Fidelity OTC Portfolio K PRO-05 - Fidelity® OTC Portfolio	Past 1 year	Past 5 years	Past 10 years
Fidelity OTC Portfolio-Class K | Return Before Taxes	(3.10%)	12.44%	19.08%
Nasdaq Composite Index®(reflects no deduction for fees, expenses, or taxes)	(2.84%)	10.97%	16.76%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Small Cap Growth Fund</b>/Fidelity Advisor® Small Cap Growth Fund A, M, C, I, Z</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund. In addition to the fees and expenses described below, your broker may also require you to pay brokerage commissions on purchases and sales of certain share classes of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity^® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 29 of the prospectus. Different intermediaries may provide additional waivers or reductions of the sales charge. Please see “Sales Charge Waiver Policies Applied by Certain Intermediaries” in the “Appendix” section of the prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(fees paid directly from your investment)</p>

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 91% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

91.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

<font style="FONT-FAMILY: Times New Roman" size="3">You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 29 of the prospectus.</font>

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Hold Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit institutional.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">institutional.fidelity.com</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Narrative [Text Block]

rr_BarChartNarrativeTextBlock

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

<font style="FONT-FAMILY: Times New Roman" size="3">The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.</font>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	23.91%	June 30, 2009
Lowest Quarter Return	-22.81%	December 31, 2018
Year-to-Date Return	26.16%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

<font style="FONT-FAMILY: Times New Roman" size="3">Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges.</font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary.</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund-Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

5.75%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.84%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.24%

Total annual operating expenses

rr_ExpensesOverAssets

1.33%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge CDSC of 1.00% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

$ 703

3 years

rr_ExpenseExampleYear03

972

5 years

rr_ExpenseExampleYear05

1,262

10 years

rr_ExpenseExampleYear10

2,084

1 Year

rr_ExpenseExampleNoRedemptionYear01

703

3 Years

rr_ExpenseExampleNoRedemptionYear03

972

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,262

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,084

2009

rr_AnnualReturn2009

42.58%

2010

rr_AnnualReturn2010

26.28%

2011

rr_AnnualReturn2011

(3.13%)

2012

rr_AnnualReturn2012

12.67%

2013

rr_AnnualReturn2013

43.99%

2014

rr_AnnualReturn2014

3.57%

2015

rr_AnnualReturn2015

5.48%

2016

rr_AnnualReturn2016

10.65%

2017

rr_AnnualReturn2017

28.64%

2018

rr_AnnualReturn2018

(4.87%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

26.16%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

23.91%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(22.81%)

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund-Class M

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

3.50%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.84%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.50%

Other expenses

rr_OtherExpensesOverAssets

0.26%

Total annual operating expenses

rr_ExpensesOverAssets

1.60%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge CDSC of 1.00% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

$ 507

3 years

rr_ExpenseExampleYear03

837

5 years

rr_ExpenseExampleYear05

1,190

10 years

rr_ExpenseExampleYear10

2,184

1 Year

rr_ExpenseExampleNoRedemptionYear01

507

3 Years

rr_ExpenseExampleNoRedemptionYear03

837

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,190

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,184

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund-Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[2]

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.84%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.25%

Total annual operating expenses

rr_ExpensesOverAssets

2.09%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

On Class C shares redeemed less than one year after purchase

1 year

rr_ExpenseExampleYear01

$ 312

3 years

rr_ExpenseExampleYear03

655

5 years

rr_ExpenseExampleYear05

1,124

10 years

rr_ExpenseExampleYear10

2,421

1 Year

rr_ExpenseExampleNoRedemptionYear01

212

3 Years

rr_ExpenseExampleNoRedemptionYear03

655

5 Years

rr_ExpenseExampleNoRedemptionYear05

1,124

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,421

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund - Class I

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.84%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.23%

Total annual operating expenses

rr_ExpensesOverAssets

1.07%

^[3]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus because of acquired fund fees and expenses. For the period, acquired fund fees and expenses are less than 0.01% and are included in other expenses.

1 year

rr_ExpenseExampleYear01

$ 109

3 years

rr_ExpenseExampleYear03

340

5 years

rr_ExpenseExampleYear05

590

10 years

rr_ExpenseExampleYear10

1,306

1 Year

rr_ExpenseExampleNoRedemptionYear01

109

3 Years

rr_ExpenseExampleNoRedemptionYear03

340

5 Years

rr_ExpenseExampleNoRedemptionYear05

590

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,306

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund-Class Z

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.84%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.09%

Total annual operating expenses

rr_ExpensesOverAssets

0.93%

^[3]

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus because of acquired fund fees and expenses. For the period, acquired fund fees and expenses are less than 0.01% and are included in other expenses.

1 year

rr_ExpenseExampleYear01

$ 95

3 years

rr_ExpenseExampleYear03

296

5 years

rr_ExpenseExampleYear05

515

10 years

rr_ExpenseExampleYear10

1,143

1 Year

rr_ExpenseExampleNoRedemptionYear01

95

3 Years

rr_ExpenseExampleNoRedemptionYear03

296

5 Years

rr_ExpenseExampleNoRedemptionYear05

515

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,143

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Return Before Taxes | Fidelity Small Cap Growth Fund-Class A

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class A - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(10.34%)

Past 5 years

rr_AverageAnnualReturnYear05

6.87%

Past 10 years

rr_AverageAnnualReturnYear10

14.71%

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Return Before Taxes | Fidelity Small Cap Growth Fund-Class M

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class M - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(8.44%)

Past 5 years

rr_AverageAnnualReturnYear05

7.08%

Past 10 years

rr_AverageAnnualReturnYear10

14.68%

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Return Before Taxes | Fidelity Small Cap Growth Fund-Class C

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class C - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(6.41%)

Past 5 years

rr_AverageAnnualReturnYear05

7.31%

Past 10 years

rr_AverageAnnualReturnYear10

14.52%

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Return Before Taxes | Fidelity Small Cap Growth Fund - Class I

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class I - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.58%)

Past 5 years

rr_AverageAnnualReturnYear05

8.46%

Past 10 years

rr_AverageAnnualReturnYear10

15.73%

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Return Before Taxes | Fidelity Small Cap Growth Fund-Class Z

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class Z - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.46%)

Past 10 years

rr_AverageAnnualReturnYear10

Since Inception

rr_AverageAnnualReturnSinceInception

9.55%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Feb. 01, 2017

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | After Taxes on Distributions | Fidelity Small Cap Growth Fund-Class A

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(13.11%)

Past 5 years

rr_AverageAnnualReturnYear05

5.14%

Past 10 years

rr_AverageAnnualReturnYear10

13.09%

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | After Taxes on Distributions and Sales | Fidelity Small Cap Growth Fund-Class A

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.31%)

Past 5 years

rr_AverageAnnualReturnYear05

5.19%

Past 10 years

rr_AverageAnnualReturnYear10

12.08%

07.31 Fidelity Small Cap Growth Fund AMCIZ PRO-07 | Fidelity® Small Cap Growth Fund | Russell 2000® Growth Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(9.31%)

Past 5 years

rr_AverageAnnualReturnYear05

5.13%

Past 10 years

rr_AverageAnnualReturnYear10

13.52%

[1] Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge CDSC of 1.00% or 0.25%, respectively.

[2] On Class C shares redeemed less than one year after purchase

[3] Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus because of acquired fund fees and expenses. For the period, acquired fund fees and expenses are less than 0.01% and are included in other expenses.

[4] Since inception February 1, 2017.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Jul. 31, 2019
Registrant Name	dei_EntityRegistrantName	FIDELITY SECURITIES FUND
Central Index Key	dei_EntityCentralIndexKey	0000754510
Investment Company Type	dei_EntityInvCompanyType	N-1A
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Sep. 26, 2019
Document Effective Date	dei_DocumentEffectiveDate	Sep. 28, 2019
Prospectus Date	rr_ProspectusDate	Sep. 28, 2019

XML

07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 | Fidelity® Blue Chip Value Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Blue Chip Value Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Blue Chip Value Fund}	07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 Fidelity® Blue Chip Value Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Blue Chip Value Fund}	07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 Fidelity® Blue Chip Value Fund Fidelity Blue Chip Value Fund-Default
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.40%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.25%
Total annual operating expenses	0.65%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Blue Chip Value Fund}	07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 Fidelity® Blue Chip Value Fund Fidelity Blue Chip Value Fund-Default USD ($)
1 year	$ 66
3 years	208
5 years	362
10 years	$ 810

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 44% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in securities of companies that Fidelity Management & Research Company (FMR) believes are undervalued in the marketplace in relation to factors such as assets, sales, earnings, growth potential, or cash flow, or in relation to securities of other companies in the same industry (stocks of these companies are often called "value" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Value" Investing. "Value" stocks can perform differently from the market as a whole and other types of stocks and can continue to be undervalued by the market for long periods of time.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	19.88%	September 30, 2009
Lowest Quarter Return	-20.55%	September 30, 2011
Year-to-Date Return	10.36%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Blue Chip Value Fund} - 07.31 Fidelity Blue Chip Growth Fund & Fidelity Blue Chip Value Fund Retail Combo PRO-04 - Fidelity® Blue Chip Value Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Blue Chip Value Fund-Default | Return Before Taxes	(8.65%)	5.30%	9.97%
Fidelity Blue Chip Value Fund-Default | After Taxes on Distributions	(9.07%)	4.93%	9.64%
Fidelity Blue Chip Value Fund-Default | After Taxes on Distributions and Sales	(4.78%)	4.12%	8.22%
Russell 1000® Value Index(reflects no deduction for fees, expenses, or taxes)	(8.27%)	5.95%	11.18%

XML

07.31 Fidelity Dividend Growth Fund Retail PRO-05 | Fidelity® Dividend Growth Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Dividend Growth Fund</b>/Fidelity® Dividend Growth Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Dividend Growth Fund}	07.31 Fidelity Dividend Growth Fund Retail PRO-05 Fidelity® Dividend Growth Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Dividend Growth Fund}	07.31 Fidelity Dividend Growth Fund Retail PRO-05 Fidelity® Dividend Growth Fund Fidelity Dividend Growth Fund-Retail Class
Management fee (fluctuates based on the fund's performance relative to a securities market index)	0.33%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.17%
Total annual operating expenses	0.50%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Dividend Growth Fund}	07.31 Fidelity Dividend Growth Fund Retail PRO-05 Fidelity® Dividend Growth Fund Fidelity Dividend Growth Fund-Retail Class USD ($)
1 year	$ 51
3 years	160
5 years	280
10 years	$ 628

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 101% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing at least 80% of assets in equity securities.

• Normally investing primarily in common stocks.

• Normally investing primarily in companies that pay dividends or that Fidelity Management & Research Company (FMR) believes have the potential to pay dividends in the future.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	28.03%	June 30, 2009
Lowest Quarter Return	-20.94%	September 30, 2011
Year-to-Date Return	15.84%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Dividend Growth Fund} - 07.31 Fidelity Dividend Growth Fund Retail PRO-05 - Fidelity® Dividend Growth Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Dividend Growth Fund-Retail Class | Return Before Taxes	(7.23%)	6.01%	13.35%
Fidelity Dividend Growth Fund-Retail Class | After Taxes on Distributions	(11.40%)	2.89%	11.27%
Fidelity Dividend Growth Fund-Retail Class | After Taxes on Distributions and Sales	(1.34%)	4.55%	10.99%
S&P 500® Index(reflects no deduction for fees, expenses, or taxes)	(4.38%)	8.49%	13.12%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity Small Cap Value Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Small Cap Value Fund</b>/Fidelity® Small Cap Value Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 79% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

79.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in securities of companies that Fidelity Management & Research Company (FMR) believes are undervalued in the marketplace in relation to factors such as assets, sales, earnings, growth potential, or cash flow, or in relation to securities of other companies in the same industry (stocks of these companies are often called "value" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Value" Investing. "Value" stocks can perform differently from the market as a whole and other types of stocks and can continue to be undervalued by the market for long periods of time.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3"> www.fidelity.com </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	25.31%	June 30, 2009
Lowest Quarter Return	-20.18%	September 30, 2011
Year-to-Date Return	12.86%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity Small Cap Value Fund | Fidelity Small Cap Value Fund

Risk/Return:

rr_RiskReturnAbstract

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.43%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.23%

Total annual operating expenses

rr_ExpensesOverAssets

0.66%

1 year

rr_ExpenseExampleYear01

$ 67

3 years

rr_ExpenseExampleYear03

211

5 years

rr_ExpenseExampleYear05

368

10 years

rr_ExpenseExampleYear10

$ 822

2009

rr_AnnualReturn2009

36.57%

2010

rr_AnnualReturn2010

25.08%

2011

rr_AnnualReturn2011

(3.64%)

2012

rr_AnnualReturn2012

20.13%

2013

rr_AnnualReturn2013

37.08%

2014

rr_AnnualReturn2014

6.62%

2015

rr_AnnualReturn2015

(1.60%)

2016

rr_AnnualReturn2016

21.28%

2017

rr_AnnualReturn2017

12.26%

2018

rr_AnnualReturn2018

(15.04%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

12.86%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

25.31%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(20.18%)

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity Small Cap Value Fund | Return Before Taxes | Fidelity Small Cap Value Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(15.04%)

Past 5 years

rr_AverageAnnualReturnYear05

3.95%

Past 10 years

rr_AverageAnnualReturnYear10

12.64%

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity Small Cap Value Fund | After Taxes on Distributions | Fidelity Small Cap Value Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(20.07%)

Past 5 years

rr_AverageAnnualReturnYear05

1.07%

Past 10 years

rr_AverageAnnualReturnYear10

10.60%

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity Small Cap Value Fund | After Taxes on Distributions and Sales | Fidelity Small Cap Value Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Small Cap Value Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.18%)

Past 5 years

rr_AverageAnnualReturnYear05

3.23%

Past 10 years

rr_AverageAnnualReturnYear10

10.56%

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity Small Cap Value Fund | Russell 2000® Value Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(12.86%)

Past 5 years

rr_AverageAnnualReturnYear05

3.61%

Past 10 years

rr_AverageAnnualReturnYear10

10.40%

XML

07.31 Fidelity Series Real Estate Income Fund Series PRO-05 | Fidelity® Series Real Estate Income Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Series Real Estate Income Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks higher than average income. As a secondary objective, the fund also seeks capital growth.

As a secondary objective, the fund also seeks capital growth.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Series Real Estate Income Fund}	07.31 Fidelity Series Real Estate Income Fund Series PRO-05 Fidelity® Series Real Estate Income Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Series Real Estate Income Fund}	07.31 Fidelity Series Real Estate Income Fund Series PRO-05 Fidelity® Series Real Estate Income Fund Fidelity Series Real Estate Income Fund-Default
Management fee	none
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	none

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Series Real Estate Income Fund}	07.31 Fidelity Series Real Estate Income Fund Series PRO-05 Fidelity® Series Real Estate Income Fund Fidelity Series Real Estate Income Fund-Default USD ($)
1 year	none
3 years	none
5 years	none
10 years	none

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 16% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in preferred and common stocks of real estate investment trusts (REITs); debt securities of real estate entities; and commercial and other mortgage-backed securities, with an emphasis on lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Normally investing at least 80% of assets in securities of companies principally engaged in the real estate industry and other real estate related investments.

• Investing in domestic and foreign issuers.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Real Estate Industry Concentration. Changes in real estate values or economic downturns can have a significant negative effect on issuers in the real estate industry. The value of securities of issuers in the real estate industry can be affected by changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, and the management skill and creditworthiness of the issuer.

• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments and can be difficult to resell.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	5.69%	March 31, 2012
Lowest Quarter Return	-2.39%	December 31, 2018
Year-to-Date Return	10.33%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Series Real Estate Income Fund} - 07.31 Fidelity Series Real Estate Income Fund Series PRO-05 - Fidelity® Series Real Estate Income Fund	Past 1 year	Past 5 years	Since Inception	[1]	Inception Date
Fidelity Series Real Estate Income Fund-Default					Oct. 20, 2011
Fidelity Series Real Estate Income Fund-Default | Return Before Taxes	0.67%	5.83%	7.59%
Fidelity Series Real Estate Income Fund-Default | After Taxes on Distributions	(1.91%)	3.70%	5.57%		Oct. 20, 2011
Fidelity Series Real Estate Income Fund-Default | After Taxes on Distributions and Sales	0.65%	4.00%	5.59%		Oct. 20, 2011
S&P 500® Index(reflects no deduction for fees, expenses, or taxes)	(4.38%)	8.49%	12.92%
Fidelity Series Real Estate Income Composite Index℠(reflects no deduction for fees, expenses, or taxes)	(3.72%)	5.34%	5.54%

[1] From October 20, 2011

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Blue Chip Growth Fund K PRO-05 | Fidelity® Blue Chip Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Blue Chip Growth Fund</b>/K</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks growth of capital over the long term.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 45% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

45.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.401k.com and log in</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	20.55%	September 30, 2009
Lowest Quarter Return	-15.99%	December 31, 2018
Year-to-Date Return	20.32%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

For the periods ended December 31, 2018

07.31 Fidelity Blue Chip Growth Fund K PRO-05 | Fidelity® Blue Chip Growth Fund | Fidelity Blue Chip Growth Fund-Class K

Risk/Return:

rr_RiskReturnAbstract

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.64%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.06%

Total annual operating expenses

rr_ExpensesOverAssets

0.70%

1 year

rr_ExpenseExampleYear01

$ 72

3 years

rr_ExpenseExampleYear03

224

5 years

rr_ExpenseExampleYear05

390

10 years

rr_ExpenseExampleYear10

$ 871

2009

rr_AnnualReturn2009

45.31%

2010

rr_AnnualReturn2010

19.80%

2011

rr_AnnualReturn2011

(2.56%)

2012

rr_AnnualReturn2012

17.95%

2013

rr_AnnualReturn2013

40.03%

2014

rr_AnnualReturn2014

14.74%

2015

rr_AnnualReturn2015

6.40%

2016

rr_AnnualReturn2016

1.71%

2017

rr_AnnualReturn2017

36.20%

2018

rr_AnnualReturn2018

1.16%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

20.32%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

20.55%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(15.99%)

07.31 Fidelity Blue Chip Growth Fund K PRO-05 | Fidelity® Blue Chip Growth Fund | Return Before Taxes | Fidelity Blue Chip Growth Fund-Class K

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Blue Chip Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class K</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

1.16%

Past 5 years

rr_AverageAnnualReturnYear05

11.34%

Past 10 years

rr_AverageAnnualReturnYear10

16.97%

07.31 Fidelity Blue Chip Growth Fund K PRO-05 | Fidelity® Blue Chip Growth Fund | Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(1.51%)

Past 5 years

rr_AverageAnnualReturnYear05

10.40%

Past 10 years

rr_AverageAnnualReturnYear10

15.29%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Growth & Income Portfolio K PRO-05 | Fidelity® Growth &amp; Income Portfolio

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Growth & Income Portfolio</b>/K</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks high total return through a combination of current income and capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 36% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

36.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing a majority of assets in common stocks with a focus on those that pay current dividends and show potential for capital appreciation.

• Potentially investing in bonds, including lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds), as well as stocks that are not currently paying dividends, but offer prospects for future income or capital appreciation.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.401k.com and log in</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	15.60%	June 30, 2009
Lowest Quarter Return	-15.03%	December 31, 2018
Year-to-Date Return	16.19%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

For the periods ended December 31, 2018

07.31 Fidelity Growth & Income Portfolio K PRO-05 | Fidelity® Growth &amp; Income Portfolio | Fidelity® Growth & Income Portfolio Class K

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

0.44%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.07%

Total annual operating expenses

rr_ExpensesOverAssets

0.51%

1 year

rr_ExpenseExampleYear01

$ 52

3 years

rr_ExpenseExampleYear03

164

5 years

rr_ExpenseExampleYear05

285

10 years

rr_ExpenseExampleYear10

$ 640

2009

rr_AnnualReturn2009

23.37%

2010

rr_AnnualReturn2010

14.82%

2011

rr_AnnualReturn2011

1.52%

2012

rr_AnnualReturn2012

19.31%

2013

rr_AnnualReturn2013

33.60%

2014

rr_AnnualReturn2014

10.53%

2015

rr_AnnualReturn2015

(2.18%)

2016

rr_AnnualReturn2016

16.22%

2017

rr_AnnualReturn2017

17.03%

2018

rr_AnnualReturn2018

(8.85%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

16.19%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

15.60%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(15.03%)

07.31 Fidelity Growth & Income Portfolio K PRO-05 | Fidelity® Growth &amp; Income Portfolio | Return Before Taxes | Fidelity® Growth & Income Portfolio Class K

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Growth & Income Portfolio

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class K</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(8.85%)

Past 5 years

rr_AverageAnnualReturnYear05

6.03%

Past 10 years

rr_AverageAnnualReturnYear10

11.88%

07.31 Fidelity Growth & Income Portfolio K PRO-05 | Fidelity® Growth &amp; Income Portfolio | S&P 500® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.38%)

Past 5 years

rr_AverageAnnualReturnYear05

8.49%

Past 10 years

rr_AverageAnnualReturnYear10

13.12%

XML

07.31 Fidelity Leveraged Company Stock Fund K PRO-05 | Fidelity® Leveraged Company Stock Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Leveraged Company Stock Fund</b>/K</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks capital appreciation.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Leveraged Company Stock Fund}	07.31 Fidelity Leveraged Company Stock Fund K PRO-05 Fidelity® Leveraged Company Stock Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Leveraged Company Stock Fund}	07.31 Fidelity Leveraged Company Stock Fund K PRO-05 Fidelity® Leveraged Company Stock Fund Fidelity Leveraged Company Stock Fund-Class K
Management fee	0.59%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.08%
Total annual operating expenses	0.67%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Leveraged Company Stock Fund}	07.31 Fidelity Leveraged Company Stock Fund K PRO-05 Fidelity® Leveraged Company Stock Fund Fidelity Leveraged Company Stock Fund-Class K USD ($)
1 year	$ 68
3 years	214
5 years	373
10 years	$ 835

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 53% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing at least 80% of assets in stocks.

• Normally investing primarily in common stocks of leveraged companies (companies that issue lower-quality debt and other companies with leveraged capital structures).

• Potentially investing in lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

• Highly Leveraged Company Exposure. Leverage can magnify the impact of adverse issuer, political, regulatory, market, or economic developments on a company.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	38.22%	June 30, 2009
Lowest Quarter Return	-26.59%	September 30, 2011
Year-to-Date Return	22.20%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

For the periods ended December 31, 2018

Effective October 1, 2019, the fund's benchmarks will change from the S&P 500^® Index and the Credit Suisse Leveraged Equity Index to the Russell Mid Cap Index and the Fidelity U.S. Leveraged Stock Linked Index℠, respectively.

Average Annual Total Returns{- Fidelity® Leveraged Company Stock Fund} - 07.31 Fidelity Leveraged Company Stock Fund K PRO-05 - Fidelity® Leveraged Company Stock Fund	Past 1 year	Past 5 years	Past 10 years
Fidelity Leveraged Company Stock Fund-Class K | Return Before Taxes	(16.33%)	1.60%	12.93%
S&P 500® Index(reflects no deduction for fees, expenses, or taxes)	(4.38%)	8.49%	13.12%
Credit Suisse Leveraged Equity Index(reflects no deduction for fees, expenses, or taxes)	(16.29%)	(0.83%)	10.07%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Real Estate Income Fund Retail PRO-07 | Fidelity Real Estate Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Real Estate Income Fund</b>/Fidelity® Real Estate Income Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks higher than average income. As a secondary objective, the fund also seeks capital growth.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

As a secondary objective, the fund also seeks capital growth.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 17% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

17.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in preferred and common stocks of real estate investment trusts (REITs); debt securities of real estate entities; and commercial and other mortgage-backed securities, with an emphasis on lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Normally investing at least 80% of assets in securities of companies principally engaged in the real estate industry and other real estate related investments.

• Investing in domestic and foreign issuers.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

Strategy Portfolio Concentration [Text]

rr_StrategyPortfolioConcentration

<font style="FONT-FAMILY: Times New Roman" size="3">Normally investing at least 80% of assets in securities of companies principally engaged in the real estate industry and other real estate related investments.</font>

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Real Estate Industry Concentration. Changes in real estate values or economic downturns can have a significant negative effect on issuers in the real estate industry. The value of securities of issuers in the real estate industry can be affected by changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, and the management skill and creditworthiness of the issuer.

• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments and can be difficult to resell. Lower-quality debt securities can be thinly traded or have restrictions on resale, making them difficult to sell at an acceptable price, and often are considered to be speculative.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.fidelity.com</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	20.55%	June 30, 2009
Lowest Quarter Return	-5.91%	September 30, 2011
Year-to-Date Return	11.60%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Real Estate Income Fund Retail PRO-07 | Fidelity Real Estate Income Fund | Fidelity Real Estate Income Fund

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

0.54%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.21%

Total annual operating expenses

rr_ExpensesOverAssets

0.75%

1 year

rr_ExpenseExampleYear01

$ 77

3 years

rr_ExpenseExampleYear03

240

5 years

rr_ExpenseExampleYear05

417

10 years

rr_ExpenseExampleYear10

$ 930

2009

rr_AnnualReturn2009

46.82%

2010

rr_AnnualReturn2010

18.81%

2011

rr_AnnualReturn2011

4.71%

2012

rr_AnnualReturn2012

18.84%

2013

rr_AnnualReturn2013

4.12%

2014

rr_AnnualReturn2014

12.49%

2015

rr_AnnualReturn2015

1.74%

2016

rr_AnnualReturn2016

10.21%

2017

rr_AnnualReturn2017

7.30%

2018

rr_AnnualReturn2018

(0.64%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

11.60%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

20.55%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(5.91%)

07.31 Fidelity Real Estate Income Fund Retail PRO-07 | Fidelity Real Estate Income Fund | Return Before Taxes | Fidelity Real Estate Income Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(0.64%)

Past 5 years

rr_AverageAnnualReturnYear05

6.10%

Past 10 years

rr_AverageAnnualReturnYear10

11.76%

07.31 Fidelity Real Estate Income Fund Retail PRO-07 | Fidelity Real Estate Income Fund | After Taxes on Distributions | Fidelity Real Estate Income Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(2.58%)

Past 5 years

rr_AverageAnnualReturnYear05

3.85%

Past 10 years

rr_AverageAnnualReturnYear10

9.45%

07.31 Fidelity Real Estate Income Fund Retail PRO-07 | Fidelity Real Estate Income Fund | After Taxes on Distributions and Sales | Fidelity Real Estate Income Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

0.11%

Past 5 years

rr_AverageAnnualReturnYear05

3.83%

Past 10 years

rr_AverageAnnualReturnYear10

8.68%

07.31 Fidelity Real Estate Income Fund Retail PRO-07 | Fidelity Real Estate Income Fund | S&P 500® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.38%)

Past 5 years

rr_AverageAnnualReturnYear05

8.49%

Past 10 years

rr_AverageAnnualReturnYear10

13.12%

07.31 Fidelity Real Estate Income Fund Retail PRO-07 | Fidelity Real Estate Income Fund | Fidelity Real Estate Income Composite Index℠(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.06%)

Past 5 years

rr_AverageAnnualReturnYear05

5.82%

Past 10 years

rr_AverageAnnualReturnYear10

11.35%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 | Fidelity® Leveraged Company Stock Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Leveraged Company Stock Fund</b>/Fidelity® Leveraged Company Stock Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 53% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

53.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in stocks.

• Normally investing primarily in common stocks of leveraged companies (companies that issue lower-quality debt and other companies with leveraged capital structures).

• Potentially investing in lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

• Highly Leveraged Company Exposure. Leverage can magnify the impact of adverse issuer, political, regulatory, market, or economic developments on a company.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3"> www.fidelity.com </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	38.14%	June 30, 2009
Lowest Quarter Return	-26.60%	September 30, 2011
Year-to-Date Return	22.14%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Market Index Changed

rr_PerformanceTableMarketIndexChanged

<font style="FONT-FAMILY: Times New Roman" size="3">Effective October 1, 2019, the fund's benchmarks will change from the S&P 500® Index and the Credit Suisse Leveraged Equity Index to the Russell Mid Cap Index and the Fidelity U.S. Leveraged Stock Linked Index℠, respectively.</font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Effective October 1, 2019, the fund's benchmarks will change from the S&P 500^® Index and the Credit Suisse Leveraged Equity Index to the Russell Mid Cap Index and the Fidelity U.S. Leveraged Stock Linked Index℠, respectively.

07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 | Fidelity® Leveraged Company Stock Fund | Fidelity Leveraged Company Stock Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

0.59%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.19%

Total annual operating expenses

rr_ExpensesOverAssets

0.78%

1 year

rr_ExpenseExampleYear01

$ 80

3 years

rr_ExpenseExampleYear03

249

5 years

rr_ExpenseExampleYear05

433

10 years

rr_ExpenseExampleYear10

$ 966

2009

rr_AnnualReturn2009

59.56%

2010

rr_AnnualReturn2010

24.51%

2011

rr_AnnualReturn2011

(10.62%)

2012

rr_AnnualReturn2012

28.82%

2013

rr_AnnualReturn2013

35.11%

2014

rr_AnnualReturn2014

5.59%

2015

rr_AnnualReturn2015

(6.05%)

2016

rr_AnnualReturn2016

7.26%

2017

rr_AnnualReturn2017

21.02%

2018

rr_AnnualReturn2018

(16.42%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

22.14%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

38.14%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(26.60%)

07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 | Fidelity® Leveraged Company Stock Fund | Return Before Taxes | Fidelity Leveraged Company Stock Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Leveraged Company Stock Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(16.42%)

Past 5 years

rr_AverageAnnualReturnYear05

1.48%

Past 10 years

rr_AverageAnnualReturnYear10

12.77%

07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 | Fidelity® Leveraged Company Stock Fund | After Taxes on Distributions | Fidelity Leveraged Company Stock Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Leveraged Company Stock Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(19.35%)

Past 5 years

rr_AverageAnnualReturnYear05

(1.55%)

Past 10 years

rr_AverageAnnualReturnYear10

11.00%

07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 | Fidelity® Leveraged Company Stock Fund | After Taxes on Distributions and Sales | Fidelity Leveraged Company Stock Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Leveraged Company Stock Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(6.94%)

Past 5 years

rr_AverageAnnualReturnYear05

1.32%

Past 10 years

rr_AverageAnnualReturnYear10

10.79%

07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 | Fidelity® Leveraged Company Stock Fund | S&P 500® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.38%)

Past 5 years

rr_AverageAnnualReturnYear05

8.49%

Past 10 years

rr_AverageAnnualReturnYear10

13.12%

07.31 Fidelity Leveraged Company Stock Fund Retail PRO-04 | Fidelity® Leveraged Company Stock Fund | Credit Suisse Leveraged Equity Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(16.29%)

Past 5 years

rr_AverageAnnualReturnYear05

(0.83%)

Past 10 years

rr_AverageAnnualReturnYear10

10.07%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Blue Chip Growth K6 Fund PRO-04 | Fidelity Blue Chip Growth K6 Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Blue Chip Growth K6 Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks growth of capital over the long term.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 51% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

51.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.401k.com and log in</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	7.75%	June 30, 2018
Lowest Quarter Return	-17.82%	December 31, 2018
Year-to-Date Return	20.92%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

For the periods ended December 31, 2018

07.31 Fidelity Blue Chip Growth K6 Fund PRO-04 | Fidelity Blue Chip Growth K6 Fund | Fidelity Blue Chip Growth K6 Fund

Risk/Return:

rr_RiskReturnAbstract

Management fee

rr_ManagementFeesOverAssets

0.45%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

Total annual operating expenses

rr_ExpensesOverAssets

0.45%

1 year

rr_ExpenseExampleYear01

$ 46

3 years

rr_ExpenseExampleYear03

144

5 years

rr_ExpenseExampleYear05

252

10 years

rr_ExpenseExampleYear10

$ 567

2018

rr_AnnualReturn2018

(2.32%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

20.92%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2018

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

7.75%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(17.82%)

Inception Date

rr_AverageAnnualReturnInceptionDate

May 25, 2017

07.31 Fidelity Blue Chip Growth K6 Fund PRO-04 | Fidelity Blue Chip Growth K6 Fund | Return Before Taxes | Fidelity Blue Chip Growth K6 Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Blue Chip Growth K6 Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Fidelity® Blue Chip Growth K6 Fund</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(2.32%)

Since Inception

rr_AverageAnnualReturnSinceInception

7.03%

^[1]

07.31 Fidelity Blue Chip Growth K6 Fund PRO-04 | Fidelity Blue Chip Growth K6 Fund | Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(1.51%)

Since Inception

rr_AverageAnnualReturnSinceInception

7.55%

^[1]

[1] From May 25, 2017

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Real Estate Income Fund</b>/Fidelity Advisor® Real Estate Income Fund A, M, C, I, Z</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks higher than average income. As a secondary objective, the fund also seeks capital growth.

Objective, Secondary [Text Block]

rr_ObjectiveSecondaryTextBlock

As a secondary objective, the fund also seeks capital growth.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund. In addition to the fees and expenses described below, your broker may also require you to pay brokerage commissions on purchases and sales of certain share classes of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity^® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 28 of the prospectus. Different intermediaries may provide additional waivers or reductions of the sales charge. Please see “Sales Charge Waiver Policies Applied by Certain Intermediaries” in the “Appendix” section of the prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(fees paid directly from your investment)</p>

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 17% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

17.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

<font style="FONT-FAMILY: Times New Roman" size="3">You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity® funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 28 of the prospectus.</font>

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Hold Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in preferred and common stocks of real estate investment trusts (REITs); debt securities of real estate entities; and commercial and other mortgage-backed securities, with an emphasis on lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).

• Normally investing at least 80% of assets in securities of companies principally engaged in the real estate industry and other real estate related investments.

• Investing in domestic and foreign issuers.

• Using fundamental analysis of each issuer's financial condition and industry position and market and economic conditions to select investments.

Strategy Portfolio Concentration [Text]

rr_StrategyPortfolioConcentration

<font style="FONT-FAMILY: Times New Roman" size="3">Normally investing at least 80% of assets in securities of companies principally engaged in the real estate industry and other real estate related investments.</font>

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Real Estate Industry Concentration. Changes in real estate values or economic downturns can have a significant negative effect on issuers in the real estate industry. The value of securities of issuers in the real estate industry can be affected by changes in real estate values and rental income, property taxes, interest rates, tax and regulatory requirements, and the management skill and creditworthiness of the issuer.

• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments and can be difficult to resell. Lower-quality debt securities can be thinly traded or have restrictions on resale, making them difficult to sell at an acceptable price, and often are considered to be speculative.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time. The indexes have characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit institutional.fidelity.com for more recent performance information.

Performance history will be available for Class Z after Class Z has been in operation for one calendar year.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and a hypothetical composite of market indexes over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">institutional.fidelity.com</font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Narrative [Text Block]

rr_BarChartNarrativeTextBlock

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

<font style="FONT-FAMILY: Times New Roman" size="3">The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.</font>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	6.67%	March 31, 2012
Lowest Quarter Return	-5.96%	September 30, 2011
Year-to-Date Return	11.36%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

<font style="FONT-FAMILY: Times New Roman" size="3">Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges.</font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary.</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Fidelity Advisor Real Estate Income Fund: Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

4.00%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee

rr_ManagementFeesOverAssets

0.54%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.22%

Total annual operating expenses

rr_ExpensesOverAssets

1.01%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

$ 499

3 years

rr_ExpenseExampleYear03

709

5 years

rr_ExpenseExampleYear05

936

10 years

rr_ExpenseExampleYear10

1,587

1 Year

rr_ExpenseExampleNoRedemptionYear01

499

3 Years

rr_ExpenseExampleNoRedemptionYear03

709

5 Years

rr_ExpenseExampleNoRedemptionYear05

936

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,587

2011

rr_AnnualReturn2011

4.47%

2012

rr_AnnualReturn2012

18.58%

2013

rr_AnnualReturn2013

3.92%

2014

rr_AnnualReturn2014

12.22%

2015

rr_AnnualReturn2015

1.55%

2016

rr_AnnualReturn2016

9.92%

2017

rr_AnnualReturn2017

7.04%

2018

rr_AnnualReturn2018

(0.82%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

11.36%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.67%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(5.96%)

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Fidelity Advisor Real Estate Income Fund: Class M

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

4.00%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee

rr_ManagementFeesOverAssets

0.54%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.25%

Total annual operating expenses

rr_ExpensesOverAssets

1.04%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

$ 502

3 years

rr_ExpenseExampleYear03

718

5 years

rr_ExpenseExampleYear05

951

10 years

rr_ExpenseExampleYear10

1,620

1 Year

rr_ExpenseExampleNoRedemptionYear01

502

3 Years

rr_ExpenseExampleNoRedemptionYear03

718

5 Years

rr_ExpenseExampleNoRedemptionYear05

951

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,620

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Fidelity Advisor Real Estate Income Fund: Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[2]

Management fee

rr_ManagementFeesOverAssets

0.54%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.22%

Total annual operating expenses

rr_ExpensesOverAssets

1.76%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

On Class C shares redeemed less than one year after purchase.

1 year

rr_ExpenseExampleYear01

$ 279

3 years

rr_ExpenseExampleYear03

554

5 years

rr_ExpenseExampleYear05

954

10 years

rr_ExpenseExampleYear10

2,073

1 Year

rr_ExpenseExampleNoRedemptionYear01

179

3 Years

rr_ExpenseExampleNoRedemptionYear03

554

5 Years

rr_ExpenseExampleNoRedemptionYear05

954

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,073

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Fidelity Advisor Real Estate Income Fund: Class I

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

Management fee

rr_ManagementFeesOverAssets

0.54%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.21%

Total annual operating expenses

rr_ExpensesOverAssets

0.75%

1 year

rr_ExpenseExampleYear01

$ 77

3 years

rr_ExpenseExampleYear03

240

5 years

rr_ExpenseExampleYear05

417

10 years

rr_ExpenseExampleYear10

930

1 Year

rr_ExpenseExampleNoRedemptionYear01

77

3 Years

rr_ExpenseExampleNoRedemptionYear03

240

5 Years

rr_ExpenseExampleNoRedemptionYear05

417

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 930

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Fidelity Advisor Real Estate Income Fund: Class Z

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) on purchases (as a % of offering price)

rr_MaximumCumulativeSalesChargeOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

Management fee

rr_ManagementFeesOverAssets

0.54%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.08%

Total annual operating expenses

rr_ExpensesOverAssets

0.62%

1 year

rr_ExpenseExampleYear01

$ 63

3 years

rr_ExpenseExampleYear03

199

5 years

rr_ExpenseExampleYear05

346

10 years

rr_ExpenseExampleYear10

774

1 Year

rr_ExpenseExampleNoRedemptionYear01

63

3 Years

rr_ExpenseExampleNoRedemptionYear03

199

5 Years

rr_ExpenseExampleNoRedemptionYear05

346

10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 774

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

<font style="FONT-FAMILY: Times New Roman" size="3">Performance history will be available for Class Z after Class Z has been in operation for one calendar year.</font>

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Return Before Taxes | Fidelity Advisor Real Estate Income Fund: Class A

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class A - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.79%)

Past 5 years

rr_AverageAnnualReturnYear05

5.00%

Since Inception

rr_AverageAnnualReturnSinceInception

6.95%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 14, 2010

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Return Before Taxes | Fidelity Advisor Real Estate Income Fund: Class M

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class M - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.89%)

Past 5 years

rr_AverageAnnualReturnYear05

4.96%

Since Inception

rr_AverageAnnualReturnSinceInception

6.92%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 14, 2010

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Return Before Taxes | Fidelity Advisor Real Estate Income Fund: Class C

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class C - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(2.59%)

Past 5 years

rr_AverageAnnualReturnYear05

5.05%

Since Inception

rr_AverageAnnualReturnSinceInception

6.64%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 14, 2010

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Return Before Taxes | Fidelity Advisor Real Estate Income Fund: Class I

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Class I - Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(0.63%)

Past 5 years

rr_AverageAnnualReturnYear05

6.13%

Since Inception

rr_AverageAnnualReturnSinceInception

7.73%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 14, 2010

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | After Taxes on Distributions | Fidelity Advisor Real Estate Income Fund: Class A

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(6.56%)

Past 5 years

rr_AverageAnnualReturnYear05

2.86%

Since Inception

rr_AverageAnnualReturnSinceInception

4.73%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 14, 2010

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | After Taxes on Distributions and Sales | Fidelity Advisor Real Estate Income Fund: Class A

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Real Estate Income Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(2.37%)

Past 5 years

rr_AverageAnnualReturnYear05

3.02%

Since Inception

rr_AverageAnnualReturnSinceInception

4.58%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

Apr. 14, 2010

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | S&P 500® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.38%)

Past 5 years

rr_AverageAnnualReturnYear05

8.49%

Since Inception

rr_AverageAnnualReturnSinceInception

11.00%

^[3]

07.31 Fidelity Real Estate Income Fund AMCIZ PRO-09 | Fidelity Real Estate Income Fund | Fidelity Real Estate Income Composite Index℠(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.06%)

Past 5 years

rr_AverageAnnualReturnYear05

5.82%

Since Inception

rr_AverageAnnualReturnSinceInception

6.61%

^[3]

[1] Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% or 0.25%, respectively.

[2] On Class C shares redeemed less than one year after purchase.

[3] From April 14, 2010.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Dividend Growth Fund Retail PRO-05 | Fidelity® Dividend Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Dividend Growth Fund</b>/Fidelity® Dividend Growth Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 101% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

101.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in equity securities.

• Normally investing primarily in common stocks.

• Normally investing primarily in companies that pay dividends or that Fidelity Management & Research Company (FMR) believes have the potential to pay dividends in the future.

• Investing in domestic and foreign issuers.

• Investing in either "growth" stocks or "value" stocks or both.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3">www.fidelity.com </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	28.03%	June 30, 2009
Lowest Quarter Return	-20.94%	September 30, 2011
Year-to-Date Return	15.84%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Dividend Growth Fund Retail PRO-05 | Fidelity® Dividend Growth Fund | Fidelity Dividend Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.33%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.17%

Total annual operating expenses

rr_ExpensesOverAssets

0.50%

1 year

rr_ExpenseExampleYear01

$ 51

3 years

rr_ExpenseExampleYear03

160

5 years

rr_ExpenseExampleYear05

280

10 years

rr_ExpenseExampleYear10

$ 628

2009

rr_AnnualReturn2009

51.00%

2010

rr_AnnualReturn2010

21.19%

2011

rr_AnnualReturn2011

(8.51%)

2012

rr_AnnualReturn2012

18.70%

2013

rr_AnnualReturn2013

31.61%

2014

rr_AnnualReturn2014

11.87%

2015

rr_AnnualReturn2015

(0.63%)

2016

rr_AnnualReturn2016

8.05%

2017

rr_AnnualReturn2017

20.14%

2018

rr_AnnualReturn2018

(7.23%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

15.84%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

28.03%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(20.94%)

07.31 Fidelity Dividend Growth Fund Retail PRO-05 | Fidelity® Dividend Growth Fund | Return Before Taxes | Fidelity Dividend Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Dividend Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(7.23%)

Past 5 years

rr_AverageAnnualReturnYear05

6.01%

Past 10 years

rr_AverageAnnualReturnYear10

13.35%

07.31 Fidelity Dividend Growth Fund Retail PRO-05 | Fidelity® Dividend Growth Fund | After Taxes on Distributions | Fidelity Dividend Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Dividend Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(11.40%)

Past 5 years

rr_AverageAnnualReturnYear05

2.89%

Past 10 years

rr_AverageAnnualReturnYear10

11.27%

07.31 Fidelity Dividend Growth Fund Retail PRO-05 | Fidelity® Dividend Growth Fund | After Taxes on Distributions and Sales | Fidelity Dividend Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Dividend Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(1.34%)

Past 5 years

rr_AverageAnnualReturnYear05

4.55%

Past 10 years

rr_AverageAnnualReturnYear10

10.99%

07.31 Fidelity Dividend Growth Fund Retail PRO-05 | Fidelity® Dividend Growth Fund | S&P 500® Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(4.38%)

Past 5 years

rr_AverageAnnualReturnYear05

8.49%

Past 10 years

rr_AverageAnnualReturnYear10

13.12%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SECURITIES FUND

Prospectus Date

rr_ProspectusDate

Sep. 28, 2019

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity® Small Cap Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: normal 12pt Arial, Helvetica, sans-serif;"><b>Fund/Class</b>:<br/><b>Fidelity® Small Cap Growth Fund</b>/Fidelity® Small Cap Growth Fund</p>

Objective [Heading]

rr_ObjectiveHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

(fees paid directly from your investment)

rr_ShareholderFeeOther

none

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 91% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

91.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Strategy [Heading]

rr_StrategyHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing primarily in common stocks.

• Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the Russell 2000^® Index or the S&P SmallCap 600^® Index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

Risk [Heading]

rr_RiskHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

• Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

<font style="FONT-FAMILY: Times New Roman" size="3">You could lose money by investing in the fund.</font>

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

<font style="FONT-FAMILY: Times New Roman" size="3">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font>

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

<font style="FONT-FAMILY: Times New Roman" size="3">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.</font>

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

<font style="FONT-FAMILY: Times New Roman" size="3"> www.fidelity.com </font>

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

<font style="FONT-FAMILY: Times New Roman" size="3">Past performance (before and after taxes) is not an indication of future performance.</font>

Bar Chart [Heading]

rr_BarChartHeading

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	23.95%	June 30, 2009
Lowest Quarter Return	-22.73%	December 31, 2018
Year-to-Date Return	26.32%	June 30, 2019

Performance Table Heading

rr_PerformanceTableHeading

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

<font style="FONT-FAMILY: Times New Roman" size="3">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.</font>

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

<font style="FONT-FAMILY: Times New Roman" size="3">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</font>

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

<font style="FONT-FAMILY: Times New Roman" size="3">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.</font>

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity® Small Cap Growth Fund | Fidelity Small Cap Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Management fee (fluctuates based on the fund's performance relative to a securities market index)

rr_ManagementFeesOverAssets

0.84%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.21%

Total annual operating expenses

rr_ExpensesOverAssets

1.05%

1 year

rr_ExpenseExampleYear01

$ 107

3 years

rr_ExpenseExampleYear03

334

5 years

rr_ExpenseExampleYear05

579

10 years

rr_ExpenseExampleYear10

$ 1,283

2009

rr_AnnualReturn2009

42.92%

2010

rr_AnnualReturn2010

26.55%

2011

rr_AnnualReturn2011

(2.83%)

2012

rr_AnnualReturn2012

13.04%

2013

rr_AnnualReturn2013

44.53%

2014

rr_AnnualReturn2014

3.86%

2015

rr_AnnualReturn2015

5.79%

2016

rr_AnnualReturn2016

10.97%

2017

rr_AnnualReturn2017

29.01%

2018

rr_AnnualReturn2018

(4.58%)

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2019

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

26.32%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

23.95%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(22.73%)

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity® Small Cap Growth Fund | Return Before Taxes | Fidelity Small Cap Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return Before Taxes</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(4.58%)

Past 5 years

rr_AverageAnnualReturnYear05

8.46%

Past 10 years

rr_AverageAnnualReturnYear10

15.73%

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity® Small Cap Growth Fund | After Taxes on Distributions | Fidelity Small Cap Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(7.46%)

Past 5 years

rr_AverageAnnualReturnYear05

6.73%

Past 10 years

rr_AverageAnnualReturnYear10

14.11%

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity® Small Cap Growth Fund | After Taxes on Distributions and Sales | Fidelity Small Cap Growth Fund-Retail Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity® Small Cap Growth Fund

Label

rr_AverageAnnualReturnLabel

<font style="FONT-FAMILY: Times New Roman" ><b>Return After Taxes on Distributions and Sale of Fund Shares</b></font>

Past 1 year

rr_AverageAnnualReturnYear01

(0.85%)

Past 5 years

rr_AverageAnnualReturnYear05

6.44%

Past 10 years

rr_AverageAnnualReturnYear10

12.99%

07.31 Fidelity Small Cap Growth Fund & Fidelity Small Cap Value Fund Retail Combo PRO-05 | Fidelity® Small Cap Growth Fund | Russell 2000® Growth Index(reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Past 1 year

rr_AverageAnnualReturnYear01

(9.31%)

Past 5 years

rr_AverageAnnualReturnYear05

5.13%

Past 10 years

rr_AverageAnnualReturnYear10

13.52%

XML

07.31 Fidelity Blue Chip Growth K6 Fund PRO-04 | Fidelity Blue Chip Growth K6 Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Blue Chip Growth K6 Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks growth of capital over the long term.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity Blue Chip Growth K6 Fund}	07.31 Fidelity Blue Chip Growth K6 Fund PRO-04 Fidelity Blue Chip Growth K6 Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity Blue Chip Growth K6 Fund}	07.31 Fidelity Blue Chip Growth K6 Fund PRO-04 Fidelity Blue Chip Growth K6 Fund Fidelity Blue Chip Growth K6 Fund
Management fee	0.45%
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	0.45%

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity Blue Chip Growth K6 Fund}	07.31 Fidelity Blue Chip Growth K6 Fund PRO-04 Fidelity Blue Chip Growth K6 Fund Fidelity Blue Chip Growth K6 Fund USD ($)
1 year	$ 46
3 years	144
5 years	252
10 years	$ 567

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 51% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	7.75%	June 30, 2018
Lowest Quarter Return	-17.82%	December 31, 2018
Year-to-Date Return	20.92%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity Blue Chip Growth K6 Fund} - 07.31 Fidelity Blue Chip Growth K6 Fund PRO-04 - Fidelity Blue Chip Growth K6 Fund	Past 1 year	Since Inception	[1]	Inception Date
Fidelity Blue Chip Growth K6 Fund				May 25, 2017
Fidelity Blue Chip Growth K6 Fund | Return Before Taxes	(2.32%)	7.03%
Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)	(1.51%)	7.55%

[1] From May 25, 2017

XML

07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 | Fidelity® Series Blue Chip Growth Fund

<p style="font: bold 20pt Arial, Helvetica, sans-serif;">Fund Summary</p><p style="font: bold 12pt Arial, Helvetica, sans-serif;">Fund:<br/>Fidelity® Series Blue Chip Growth Fund</p>

<font style="font: bold 16pt Arial, Helvetica, sans-serif;">Investment Objective</font>

The fund seeks growth of capital over the long term.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Fee Table</b></font>

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Shareholder fees</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px"></p>

Shareholder Fees {- Fidelity® Series Blue Chip Growth Fund}	07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 Fidelity® Series Blue Chip Growth Fund USD ($)
(fees paid directly from your investment)	none

<p style="font: bold 11pt Arial, sans-serif; margin-bottom: 0px;">Annual Operating Expenses</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">(expenses that you pay each year as a % of the value of your investment)</p>

Annual Operating Expenses {- Fidelity® Series Blue Chip Growth Fund}	07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 Fidelity® Series Blue Chip Growth Fund Fidelity Series Blue Chip Growth Fund-Default
Management fee	none
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	none

This example helps compare the cost of investing in the fund with the cost of investing in other funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

<p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Sell All Shares</p>

Expense Example {- Fidelity® Series Blue Chip Growth Fund}	07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 Fidelity® Series Blue Chip Growth Fund Fidelity Series Blue Chip Growth Fund-Default USD ($)
1 year	none
3 years	none
5 years	none
10 years	none

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Portfolio Turnover</b></font>

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 53% of the average value of its portfolio.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Strategies</b></font>

• Normally investing primarily in common stocks of well-known and established companies.

• Normally investing at least 80% of assets in blue chip companies (companies whose stock is included in the S&P 500^® Index or the Dow Jones Industrial Average℠ (DJIA℠), and companies with market capitalizations of at least $1 billion if not included in either index).

• Investing in companies that Fidelity Management & Research Company (FMR) believes have above-average growth potential (stocks of these companies are often called "growth" stocks).

• Investing in securities of domestic and foreign issuers.

• Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Principal Investment Risks</b></font>

• Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments.

• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.

• "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. You could lose money by investing in the fund.

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Performance</b></font>

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for more recent performance information.

<p style="font:bold 11pt Arial, sans-serif; margin-bottom: 0px;">Year-by-Year Returns</p><p style="font: bold 9pt Arial, sans-serif; margin-top: 0px">Calendar Years</p>

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	11.75%	March 31, 2017
Lowest Quarter Return	-14.21%	December 31, 2018
Year-to-Date Return	20.19%	June 30, 2019

<font style="font: bold 16pt Arial, Helvetica, sans-serif;"><b>Average Annual Returns</b></font>

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended December 31, 2018

Average Annual Total Returns{- Fidelity® Series Blue Chip Growth Fund} - 07.31 Fidelity Series Blue Chip Growth Fund Series PRO-05 - Fidelity® Series Blue Chip Growth Fund	Past 1 year	Past 5 years	Since Inception	[1]	Inception Date
Fidelity Series Blue Chip Growth Fund-Default					Nov. 07, 2013
Fidelity Series Blue Chip Growth Fund-Default | Return Before Taxes	4.65%	12.11%	13.13%
Fidelity Series Blue Chip Growth Fund-Default | After Taxes on Distributions	1.41%	10.05%	11.10%		Nov. 07, 2013
Fidelity Series Blue Chip Growth Fund-Default | After Taxes on Distributions and Sales	5.40%	9.47%	10.34%		Nov. 07, 2013
Russell 1000® Growth Index(reflects no deduction for fees, expenses, or taxes)	(1.51%)	10.40%	11.48%

[1] From November 7, 2013