Risk/Return Detail Data - FidelityAssetManagerFunds-RetailComboPRO	Nov. 29, 2023 USD ($)
Risk/Return:
Registrant Name	Fidelity Charles Street Trust
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 30%
Risk/Return:
Risk/Return [Heading]	Fund Summary Fund/Class: Fidelity Asset Manager® 30%/Fidelity Asset Manager® 30%
Objective [Heading]	Investment Objective
Objective, Primary [Text Block]	Fidelity Asset Manager® 30% seeks a high level of current income by allocating its assets among stocks, bonds, short-term instruments and other investments. The fund also considers the potential for capital appreciation.
Expense [Heading]	Fee Table
Expense Narrative [Text Block]	The following table describes the fees and expenses that may be incurred when you buy, hold, and sell 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.
Shareholder Fees Caption [Text]	Shareholder fees
(fees paid directly from your investment)	none
Operating Expenses Caption [Text]	Annual Operating Expenses
Portfolio Turnover [Heading]	Portfolio Turnover
Portfolio Turnover [Text Block]	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 22% of the average value of its portfolio.
Portfolio Turnover, Rate	22.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	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.
Expense Example Narrative [Text Block]	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 the 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:
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	Allocating the fund's assets among three main asset classes: the stock class (equity securities of all types, including funds that invest in such securities), the bond class (fixed-income securities of all types maturing in more than one year, including lower-quality debt securities which are sometimes referred to as high yield debt securities or junk bonds, and funds that invest in such securities), and the short-term/money market class (fixed-income securities of all types maturing in one year or less, including funds that invest in such securities).Maintaining a neutral mix over time of 30% of assets in stocks, 50% of assets in bonds, and 20% of assets in short-term and money market instruments.Adjusting allocation among asset classes gradually within the following ranges: stock class (20%-40%), bond class (40%-60%), and short-term/money market class (0%-50%).Investing in domestic and foreign issuers.Investing in Fidelity's Central funds (specialized investment vehicles used by Fidelity® funds to invest in particular security types or investment disciplines) consistent with the asset classes discussed above.
Risk [Heading]	Principal Investment Risks
Risk Narrative [Text Block]	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. Income Risk. A low or negative interest rate environment can adversely affect an underlying fund's yield. 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. The extent of economic development; political stability; market depth, infrastructure, and capitalization; and regulatory oversight can be less than in more developed markets. Emerging markets typically have less established legal, accounting and financial reporting systems than those in more developed markets, which may reduce the scope or quality of financial information available to investors. Emerging markets can be subject to greater social, economic, regulatory, and political uncertainties and can be extremely volatile. Foreign exchange rates also can be extremely volatile. 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. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. 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]	You could lose money by investing in the fund.
Risk Not Insured Depository Institution [Text]	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.
Bar Chart and Performance Table [Heading]	Performance
Performance Narrative [Text Block]	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]	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.
Performance Availability Website Address [Text]	www.fidelity.com
Performance Past Does Not Indicate Future [Text]	Past performance (before and after taxes) is not an indication of future performance.
Bar Chart [Heading]	Year-by-Year Returns
Year to Date Return, Label	Year-to-Date Return
Bar Chart, Year to Date Return, Date	Sep. 30, 2023
Bar Chart, Year to Date Return	2.30%
Highest Quarterly Return, Label	Highest Quarter Return
Highest Quarterly Return, Date	Jun. 30, 2020
Highest Quarterly Return	9.92%
Lowest Quarterly Return, Label	Lowest Quarter Return
Lowest Quarterly Return, Date	Jun. 30, 2022
Lowest Quarterly Return	(7.92%)
Performance Table Heading	Average Annual Returns
Performance Table Uses Highest Federal Rate	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.
Performance Table Not Relevant to Tax Deferred	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).
Performance Table Explanation after Tax Higher	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.
Performance Table Narrative	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.
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 30% | Fidelity Asset Manager 30%
Risk/Return:
Management fee	0.40%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.13%
Total annual operating expenses	0.53%	[1]
1 year	$ 54
3 years	170
5 years	296
10 years	$ 665
2013	7.94%
2014	4.83%
2015	(0.29%)
2016	5.50%
2017	9.43%
2018	(2.91%)
2019	13.51%
2020	11.08%
2021	6.03%
2022	(12.31%)
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 30% | Return Before Taxes | Fidelity Asset Manager 30%
Risk/Return:
Label	Return Before Taxes
Past 1 year	(12.31%)
Past 5 years	2.62%
Past 10 years	4.02%
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 30% | After Taxes on Distributions | Fidelity Asset Manager 30%
Risk/Return:
Label	Return After Taxes on Distributions
Past 1 year	(13.57%)
Past 5 years	1.55%
Past 10 years	2.91%
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 30% | After Taxes on Distributions and Sales | Fidelity Asset Manager 30%
Risk/Return:
Label	Return After Taxes on Distributions and Sale of Fund Shares
Past 1 year	(6.86%)
Past 5 years	1.71%
Past 10 years	2.79%
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 30% | LB001
Risk/Return:
Label	Bloomberg U.S. Aggregate Bond Index
Past 1 year	(13.01%)
Past 5 years	0.02%
Past 10 years	1.06%
FidelityAssetManagerFunds-RetailComboPRO | Fidelity Asset Manager 30% | F0593
Risk/Return:
Label	Fidelity Asset Manager 30% Composite Index℠
Past 1 year	(11.57%)
Past 5 years	2.50%
Past 10 years	3.82%

[1] ADiffers 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.