485BPOS

As Filed with the U.S. Securities and Exchange Commission on January 18, 2019

1933 Act File No. 002-82734

1940 Act File No. 811-03706

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549
__________________
FORM N-1A __________________
REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	☒
Pre-Effective Amendment No.	☐
Post-Effective Amendment No. 66	☒
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	☒
Amendment No. 70	☒
(Check appropriate box or boxes.)
__________________
American Century California Tax-Free and Municipal Funds
__________________
4500 MAIN STREET, KANSAS CITY, MISSOURI 64111 (Address of Principal Executive Offices)(Zip Code)
REGISTRANT’S TELEPHONE NUMBER, INCLUDING AREA CODE: (816) 531-5575
CHARLES A. ETHERINGTON 4500 MAIN STREET, KANSAS CITY, MISSOURI 64111 (Name and Address of Agent for Service)
It is proposed that this filing will become effective (check appropriate box)

☒	immediately upon filing pursuant to paragraph (b)
☐	on (date) pursuant to paragraph (b)
☐	60 days after filing pursuant to paragraph (a)(1)
☐	on (date) pursuant to paragraph (a)(1)
☐	75 days after filing pursuant to paragraph (a)(2)
☐	on (date) pursuant to paragraph (a)(2) of rule 485.
If appropriate, check the following box:
☐	this post-effective amendment designates a new effective date for a previously filed post-effective amendment.

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 effectiveness of this Registration Statement amendment pursuant to Rule 485(b) promulgated under the Securities Act of 1933, as amended, and has duly caused this amendment to be signed on its behalf by the undersigned, duly authorized, in the City of Kansas City, State of Missouri on the 18th day of January, 2019.

American Century California Tax-Free and Municipal Funds

(Registrant)

By:

*

___________________________________

Jonathan S. Thomas

President

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

SIGNATURES	TITLE	DATE
* _________________________________ Jonathan S. Thomas	President and Trustee	January 18, 2019
* _________________________________ R. Wes Campbell	Chief Financial Officer and Treasurer	January 18, 2019
* _________________________________ Tanya S. Beder	Trustee	January 18, 2019
* _________________________________ Jeremy I. Bulow	Trustee	January 18, 2019
* _________________________________ Anne Casscells	Trustee	January 18, 2019
* _________________________________ Ronald J. Gilson	Chairman of the Board and Trustee	January 18, 2019
* _________________________________ Frederick L.A. Grauer	Trustee	January 18, 2019
* _________________________________ Jonathan D. Levin	Trustee	January 18, 2019
* _________________________________ Peter F. Pervere	Trustee	January 18, 2019
* _________________________________ John B. Shoven	Trustee	January 18, 2019

*By:	/s/ Giles Walsh
	Giles Walsh
	Attorney in Fact
	(pursuant to Power of Attorney
	dated September 21, 2018)

Pursuant to Power of Attorney, dated September 21, 2018 (filed electronically as Exhibit q1 to Post-Effective Amendment No. 78 to the Registration Statement of American Century Municipal Trust on September 28, 2018, File No. 002-91229, and incorporated herein by reference). 

Secretary’s Certificate, dated September 21, 2018 (filed electronically as Exhibit q2 to Post-Effective Amendment No. 78 to the Registration Statement of American Century Municipal Trust on September 28, 2018, File No. 002-91229, and incorporated herein by reference). 

EXHIBIT INDEX

EXHIBIT NUMBER	DESCRIPTION OF DOCUMENT
Exhibit - 101.CAL	XBRL Taxonomy Extension Calculation Linkbase Document
Exhibit - 101.INS	XBRL Instance Document
Exhibit - 101.SCH	XBRL Taxonomy Extension Schema Document
Exhibit - 101.DEF	XBRL Taxonomy Extension Definition Linkbase Document
Exhibit - 101.LAB	XBRL Taxonomy Extension Label Linkbase Document
Exhibit - 101.PRE	XBRL Taxonomy Extension Presentation Linkbase Document

XML

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund

California High-Yield Municipal Fund

Investment Objective

The fund seeks high current income that is exempt from federal and California income taxes.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold shares of the fund. You may qualify for A Class sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in American Century Investments funds. More information about these and other discounts is available from your financial professional and in Calculation of Sales Charges on page 12 of the fund’s prospectus, Appendix A of the fund’s prospectus and Sales Charges in Appendix B of the statement of additional information.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - American Century California Tax-Free and Municipal Funds - California High-Yield Municipal Fund - USD ($)	Investor Class	I Class	Y Class	A Class		C Class
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)	none	none	none	4.50%		none
Maximum Deferred Sales Charge (as a percentage)	none	none	none	none	[1]	1.00%
Maximum Account Fee	$ 25	none	none	none		none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - American Century California Tax-Free and Municipal Funds - California High-Yield Municipal Fund	Investor Class	I Class	Y Class	A Class	C Class
Management Fees (as a percentage of Assets)	0.49%	0.29%	0.26%	0.49%	0.49%
Distribution and Service (12b-1) Fees	none	none	none	0.25%	1.00%
Other Expenses (as a percentage of Assets):	0.01%	0.01%	0.01%	0.01%	0.01%
Expenses (as a percentage of Assets)	0.50%	0.30%	0.27%	0.75%	1.50%

Example

The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.

The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, that you earn a 5% return each year, and that the fund’s operating expenses remain the same. You may be required to pay brokerage commissions on your purchases of Investor, I or Y Class shares of the fund, which are not reflected in the example. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - American Century California Tax-Free and Municipal Funds - California High-Yield Municipal Fund - USD ($)	Expense Example, with Redemption, 1 Year	Expense Example, with Redemption, 3 Years	Expense Example, with Redemption, 5 Years	Expense Example, with Redemption, 10 Years
Investor Class	51	161	280	629
I Class	31	97	169	381
Y Class	28	87	152	344
A Class	523	679	849	1,339
C Class	153	475	819	1,789

Portfolio Turnover

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 fund operating expenses or in the example, affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was52% of the average value of its portfolio.

Principal Investment Strategies

The fund invests in California municipal and other debt securities with an emphasis on high-yield securities. A high-yield security is one that has been rated below investment-grade, or determined by the investment advisor to be of similar quality. Under normal market conditions, the portfolio managers invest at least 80% of the fund’s net assets in municipal securities with income payments exempt from federal and California income taxes. Cities, counties and other municipalities in California and U.S. territories usually issue these securities for public projects, such as schools, roads, and water and sewer systems. Some of these investments are not necessarily exempt from the federal alternative minimum tax. 

The portfolio managers seek to invest in securities that will result in a high yield for the fund. To accomplish this, the portfolio managers buy securities that are rated below investment-grade, including so-called junk bonds and bonds that are in technical or monetary default. Issuers of these securities often have short financial histories or have questionable credit or have had and may continue to have problems making interest and principal payments. 

The portfolio managers also may buy unrated securities if they determine such securities meet the investment objectives of the fund. 

Although the fund invests primarily for income, it also employs techniques designed to realize capital appreciation. For example, the portfolio managers may select bonds with maturities and coupon rates that position the fund for potential capital appreciation for a variety of reasons, including their view on the direction of future interest-rate movements and the potential for a credit upgrade.

When determining whether to sell a security, the portfolio managers consider, among other things, current and anticipated changes in interest rates, the credit quality of a particular issuer, comparable alternatives, general market conditions and any other factor deemed relevant by the portfolio managers. 

Principal Risks 

• Credit Risk – Debt securities, even investment-grade debt securities, are subject to credit risk. Credit risk is the risk that the inability or perceived inability of the issuer to make interest and principal payments will cause the value of the securities to decrease. As a result, the fund’s share price could also decrease. Changes in the credit rating of a debt security held by the fund could have a similar effect. The fund’s investments often have high credit risk, which helps the fund pursue a higher yield than more conservatively managed bond funds.

• Below Investment-Grade Securities Risk – Issuers of lower rated, high-yield securities are more vulnerable to real or perceived economic changes (such as an economic downturn or a prolonged period of rising interest rates), political changes, or adverse developments specific to the issuer. Adverse economic, political and other developments may be more likely to cause an issuer of low-quality bonds to default on its obligation to pay interest and principal due under its securities. The fund invests a significant part of its assets in securities rated below investment-grade or that are unrated, including bonds that are in technical or monetary default. By definition, the issuers of many of these securities have had and may continue to have problems making interest and principal payments.

• Interest Rate Risk – When interest rates change, the fund’s share value will be affected. Generally, the value of debt securities and the funds that hold them decline as interest rates rise. Because the fund typically invests in intermediate-term and long-term bonds, the fund’s interest rate risk is generally higher than for funds with shorter-weighted average maturities, such as money market and short-term bond funds. A period of rising interest rates may negatively affect the fund’s performance.

• California Economic Risk – The fund will be sensitive to events that affect California’s economy. Significant political or economic developments in California will likely impact virtually all municipal securities issued in the state. Because the fund invests principally in California municipal securities, it may have a higher level of risk than funds that invest in a larger universe of securities.

• Municipal Securities Risk – Because the fund invests principally in municipal securities, it will be sensitive to events that affect municipal markets, including legislative or political changes and the financial condition of the issuers of municipal securities. The fund may have a higher level of risk than funds that invest in a larger universe of securities.

• Liquidity Risk – The fund may also be subject to liquidity risk. During periods of market turbulence or unusually low trading activity, in order to meet redemptions, it may be necessary for the fund to sell securities at prices that could have an adverse effect on the fund’s share price. Changing regulatory and market conditions, including increases in interest rates and credit spreads may adversely affect the liquidity of the fund’s investments.

• Tax Risk – Some or all of the fund’s income may be subject to the federal alternative minimum tax. There is no guarantee that all of the fund’s income will remain exempt from federal or state income taxes. Income from municipal bonds held by a fund could be declared taxable because of unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or non-compliant conduct of a bond issuer. The fund may sell securities that lose their tax-exempt statuses at inopportune times, which may cause tax consequences or a decrease in the fund’s value.

• Market Risk – The value of securities owned by the fund may go up and down, sometimes rapidly or unpredictably.

• Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.

An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. 

Fund Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. Because the Y Class does not have investment performance for a full calendar year, it is not included. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com. 

Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown. 

Calendar Year Total Returns

Highest Performance Quarter (3Q 2009): 12.08%Lowest Performance Quarter (4Q 2008): -9.36%

As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 0.35%.

Average Annual Total Returns For the calendar year ended December 31, 2017

Average Annual Total Returns - American Century California Tax-Free and Municipal Funds - California High-Yield Municipal Fund		Label	1 Year	5 Years	10 Years	Since Inception	Inception Date
Bloomberg Barclays Municipal Bond Index		Bloomberg Barclays Municipal Bond Index    (reflects no deduction for fees, expenses and taxes)	5.45%	3.02%	4.45%
S&P Municipal Bond California 50% Investment Grade/50% High Yield Index	[1]	S&P Municipal Bond California 50% Investment Grade/50% High Yield Index1    (reflects no deduction for fees, expenses and taxes)	9.19%	5.65%
Investor Class		Investor Class Return Before Taxes	8.48%	4.73%	5.37%		Dec. 30, 1986
Investor Class | After Taxes on Distributions		Return After Taxes on Distributions	8.48%	4.73%	5.37%		Dec. 30, 1986
Investor Class | After Taxes on Distributions and Sales		Return After Taxes on Distributions and Sale of Fund Shares	6.41%	4.52%	5.16%		Dec. 30, 1986
I Class		I Class Return Before Taxes	8.60%	4.92%		6.27%	Mar. 01, 2010
A Class		A Class Return Before Taxes	3.35%	3.51%	4.63%		Jan. 31, 2003
C Class		C Class Return Before Taxes	7.41%	3.69%	4.32%		Jan. 31, 2003

After-tax returns are shown only for Investor Class shares. After-tax returns for other share classes will vary. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund

California Intermediate-Term Tax-Free Bond FundCalifornia Tax-Free Money Market Fund

Investment Objective 

The fund seeks safety of principal and high current income that is exempt from federal and California income taxes. 

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold shares of the fund. You may qualify for A Class sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in American Century Investments funds. More information about these and other discounts is available from your financial professional and in Calculation of Sales Charges on page 12 of the fund’s prospectus, Appendix A of the fund’s prospectus and Sales Charges in Appendix B of the statement of additional information.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - American Century California Tax-Free and Municipal Funds - California Intermediate-Term Tax-Free Bond Fund - USD ($)	Investor Class	I Class	Y Class	A Class		C Class
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)	none	none	none	4.50%		none
Maximum Deferred Sales Charge (as a percentage)	none	none	none	none	[1]	1.00%
Maximum Account Fee	$ 25	none	none	none		none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - American Century California Tax-Free and Municipal Funds - California Intermediate-Term Tax-Free Bond Fund	Investor Class	I Class	Y Class	A Class	C Class
Management Fees (as a percentage of Assets)	0.46%	0.26%	0.23%	0.46%	0.46%
Distribution and Service (12b-1) Fees	none	none	none	0.25%	1.00%
Other Expenses (as a percentage of Assets):	0.01%	0.01%	0.01%	0.01%	0.01%
Expenses (as a percentage of Assets)	0.47%	0.27%	0.24%	0.72%	1.47%

Example

The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.

The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, that you earn a 5% return each year, and that the fund’s operating expenses remain the same. You may be required to pay brokerage commissions on your purchases of Investor, I or Y Class shares of the fund, which are not reflected in the example. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example - American Century California Tax-Free and Municipal Funds - California Intermediate-Term Tax-Free Bond Fund - USD ($)	Expense Example, with Redemption, 1 Year	Expense Example, with Redemption, 3 Years	Expense Example, with Redemption, 5 Years	Expense Example, with Redemption, 10 Years
Investor Class	48	151	264	592
I Class	28	87	152	344
Y Class	25	77	135	306
A Class	520	670	833	1,305
C Class	150	466	803	1,756

Portfolio Turnover

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 fund operating expenses or in the example, affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 52%of the average value of its portfolio.

Principal Investment Strategies

The portfolio managers primarily buy investment-grade debt securities and, under normal market conditions, will invest at least 80% of the fund’s net assets in debt securities that have interest payments exempt from federal and California income taxes. Cities, counties and other municipalities in California and U.S. territories, such as Puerto Rico, issue these securities.

The fund’s weighted average maturity will be not less than three years nor more than ten years. However, there is no maturity limit on individual securities. 

Although the fund invests primarily in investment-grade securities, up to 20% of the value of the fund’s net assets may be invested in below investment-grade securities, also known as junk bonds. The fund also may invest in securities which, while not rated, are determined by the portfolio managers to be of comparable credit quality to those rated below investment-grade. 

When determining whether to sell a security, portfolio managers consider, among other things, current and anticipated changes in interest rates, the credit quality of a particular issuer, comparable alternatives, general market conditions and any other factor deemed relevant by the portfolio managers. 

Principal Risks

• Credit Risk – Debt securities, even investment-grade debt securities, are subject to credit risk. Credit risk is the risk that the inability or perceived inability of the issuer to make interest and principal payments will cause the value of the securities to decrease. As a result, the fund’s share price could also decrease. Changes in the credit rating of a debt security held by the fund could have a similar effect.

• Below Investment-Grade Securities Risk – Issuers of lower rated, high-yield securities are more vulnerable to real or perceived economic changes (such as an economic downturn or a prolonged period of rising interest rates), political changes or adverse developments specific to an issuer. These factors may be more likely to cause an issuer of low quality bonds to default on its obligations.

• Interest Rate Risk – Investments in debt securities are sensitive to interest rate changes. Generally, the value of debt securities and the funds that hold them decline as interest rates rise. The fund’s interest rate risk is moderate under normal market conditions, but it may fluctuate as the portfolio managers reposition the fund in response to changing market conditions. A period of rising interest rates may negatively affect the fund’s performance.

• California Economic Risk – The fund will be sensitive to events that affect California’s economy. Significant political or economic developments in California will likely impact virtually all municipal securities issued in the state. Because the fund invests principally in California municipal securities, it may have a higher level of risk than funds that invest in a larger universe of securities.

• Municipal Securities Risk – The fund invests principally in municipal securities, so it will be sensitive to events that affect municipal markets, including legislative or political changes and the financial condition of the issuers of municipal securities. By investing primarily in municipal securities, the fund may have a higher level of risk than funds that invest in a larger universe of securities.

• Loss of Tax Exemptions Risk – There is no guarantee that all of the fund’s income will be exempt from federal or state income taxes. Income from municipal bonds held by the fund could be declared taxable because of unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or non-compliant conduct of a bond issuer. The fund may sell securities that lose their tax-exempt statuses at inopportune times, which may cause tax consequences or a decrease in the fund’s value.

• Liquidity Risk – The fund may also be subject to liquidity risk. During periods of market turbulence or unusually low trading activity, to meet redemptions, it may be necessary for the fund to sell securities at prices that could have an adverse effect on the fund’s share price. Changing regulatory and market conditions, including increases in interest rates and credit spreads may adversely affect the liquidity of the fund’s investments.

• Market Risk – The value of securities owned by the fund may go up and down, sometimes rapidly or unpredictably.

• Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.

An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Fund Performance 

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. Because the Y Class does not have investment performance for a full calendar year, it is not included. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.

Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.

Calendar Year Total Returns

Highest Performance Quarter (3Q 2009): 6.57%Lowest Performance Quarter (4Q 2010): -4.11%

As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was -0.51%.

Average Annual Total Returns For the calendar year ended December 31, 2017

Average Annual Total Returns - American Century California Tax-Free and Municipal Funds - California Intermediate-Term Tax-Free Bond Fund		Label	1 Year	5 Years	10 Years	Since Inception	Inception Date
Bloomberg Barclays 7 Year Municipal Bond Index		Bloomberg Barclays 7 Year Municipal Bond Index    (reflects no deduction for fees, expenses and taxes)	4.49%	2.44%	4.30%
S&P Intermediate Term California AMT-Free Municipal Bond Index	[1]	S&P Intermediate Term California AMT-Free Municipal Bond Index2    (reflects no deduction for fees, expenses and taxes)	3.83%	2.63%
Investor Class		Investor Class Return Before Taxes	4.62%	2.34%	3.86%		Nov. 09, 1983
Investor Class | After Taxes on Distributions		Return After Taxes on Distributions	4.62%	2.34%	3.86%		Nov. 09, 1983
Investor Class | After Taxes on Distributions and Sales		Return After Taxes on Distributions and Sale of Fund Shares	3.72%	2.37%	3.70%		Nov. 09, 1983
I Class		I Class Return Before Taxes	4.83%	2.55%		3.81%	Mar. 01, 2010
A Class	[2]	A Class1 Return Before Taxes	(0.34%)	1.16%	3.12%		Mar. 01, 2010
C Class	[2]	C Class1 Return Before Taxes	3.58%	1.35%	2.84%		Mar. 01, 2010

After-tax returns are shown only for Investor Class shares. After-tax returns for other share classes will vary. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.

American Century California Tax-Free and Municipal Funds | California Tax-Free Money Market Fund

Investment Objective

The fund seeks safety of principal and high current income that is exempt from federal and California income taxes.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold shares of the fund.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	USD ($)
Maximum Account Fee | American Century California Tax-Free and Municipal Funds | California Tax-Free Money Market Fund	$ 25

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	American Century California Tax-Free and Municipal Funds California Tax-Free Money Market Fund
Management Fees (as a percentage of Assets)	0.49%
Distribution and Service (12b-1) Fees	none
Other Expenses (as a percentage of Assets):	0.01%
Expenses (as a percentage of Assets)	0.50%

Example

The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.

The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, that you earn a 5% return each year, and that the fund’s operating expenses remain the same. You may be required to pay brokerage commissions on your purchases of Investor Class shares of the fund, which are not reflected in the example. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	Expense Example, with Redemption, 1 Year	Expense Example, with Redemption, 3 Years	Expense Example, with Redemption, 5 Years	Expense Example, with Redemption, 10 Years
American Century California Tax-Free and Municipal Funds | California Tax-Free Money Market Fund | Investor Class | USD ($)	51	161	280	629

Principal Investment Strategies

The fund is a retail money market fund that invests in municipal money market securities. The securities purchased by the fund are subject to the maturity, quality, diversification, and other requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended. Although the fund seeks to maintain a $1.00 share price, there is no guarantee it will be able to do so. Under normal market conditions, the fund invests in cash-equivalent, high-quality debt securities, at least 80% of which have interest payments exempt from federal and California income taxes. Cities, counties, other municipalities in California and U.S. territories may issue the securities. A high-quality debt security is one an independent rating agency rates in its top two credit quality categories or that the advisor determines to be of comparable credit quality.

Some of the securities in which the fund invests are guaranteed by certain U.S. government agencies or instrumentalities such as the Federal Home Loan Bank (FHLB), the Federal National Mortgage Association (Fannie Mae), and the Federal Home Loan Mortgage Corporation (Freddie Mac). Such securities are not guaranteed by the U.S. Treasury or supported by the full faith and credit of the U.S. government. However, these agencies are authorized to borrow from the U.S. Treasury to meet their obligations. 

When determining whether to buy or sell a security, portfolio managers may consider, among other things, current and anticipated changes in interest rates, issuer credit quality, comparable alternatives, diversification limits, general market conditions and any other factor deemed relevant by the portfolio managers.

Principal Risks

• Low Yield – Because high-quality debt securities are among the safest securities available, the interest they pay is among the lowest for income-paying securities. Accordingly, the yield on this fund will likely be lower than the yield on funds that invest in lower-quality or longer-term securities.

• California Economic Risk – The fund will be sensitive to events that affect California’s economy. Significant political or economic developments in California will likely impact virtually all municipal securities issued in the state. Because the fund invests principally in California municipal securities, it may have a higher level of risk than funds that invest in a larger universe of securities.

• Municipal Securities Risk – Because the fund invests principally in municipal securities, it will be sensitive to events that affect municipal markets, including legislative or political changes and the financial condition of the issuers of municipal securities. By investing primarily in municipal securities, the fund may have a higher level of risk than funds that invest in a larger universe of securities.

• Interest Rate Risk – Interest rate risk means that the value of debt securities and the funds that hold them decline as interest rates rise. A period of rising interest rates may negatively affect the fund’s performance.

• Credit Risk – Credit risk is the risk that the inability or perceived inability of the issuer to make interest and principal payments will cause the value of the securities to decrease.

• Liquidity Risk – Liquidity risk means that during periods of market turbulence or unusually low trading activity, to meet redemptions it may be necessary for the fund to sell securities at prices that could have an adverse effect on the fund’s share price. Changing regulatory and market conditions may adversely affect the liquidity of the fund’s investments. If liquidity decreases too much, the fund may impose a fee on the sale of shares or temporarily suspend redemptions.

• Loss of Tax Exemptions Risk – There is no guarantee that all of the fund’s income will be exempt from federal or state income taxes. Income from municipal bonds held by the fund could be declared taxable because of unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or non-compliant conduct of a bond issuer. The fund may sell securities that lose their tax-exempt statuses at inopportune times, which may cause tax consequences or a decrease in the fund’s value.

• Principal Loss – You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund may impose a fee upon sale of your shares or may temporarily suspend your ability to sell shares if the fund’s liquidity falls below required minimums because of market conditions or other factors. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The fund’s sponsor has no legal obligation to provide financial support to the fund, and you should not expect that the sponsor will provide financial support to the fund at any time.

Fund Performance

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year. The fund’s past performance is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com. 

Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.

Calendar Year Total Returns

Highest Performance Quarter(1Q 2008): 0.58%Lowest Performance Quarter (1Q 2010): 0.00%

As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 0.65%.

Average Annual Total Returns For the calendar year ended December 31, 2017

Average Annual Total Returns	Label	1 Year	5 Years	10 Years
American Century California Tax-Free and Municipal Funds | California Tax-Free Money Market Fund | Investor Class	Investor Class	0.42%	0.11%	0.27%

[1] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.

[1] Effective December 31, 2017, the fund’s investment advisor selected a different benchmark for comparison purposes. The advisor believes the S&P Municipal Bond California 50% Investment Grade/50% High Yield Index is more reflective of the fund’s strategy. Because the S&P Municipal Bond California 50% Investment Grade/50% High Yield Index total return data is first available as of December 30, 2011, returns for the Bloomberg Barclays Municipal Bond Index are also shown to cover the 10 year period.

[1] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.

[1] Effective December 31, 2017, the fund’s investment advisor selected a different benchmark for comparison purposes. The advisor believes the S&P Intermediate Term California AMT-Free Municipal Bond Index is more reflective of the fund’s strategy. Because the S&P Intermediate Term California AMT-Free Municipal Bond Index total return data is first available as of June 30, 2010, returns for the Bloomberg Barclays 7 Year Municipal Bond Index are also shown to cover the 10 year period.

[2] Historical performance for A and C Classes prior to their inception is based on the performance of Investor Class shares. A and C Class performance has been adjusted to reflect differences in sales charges, if applicable, and expenses between classes.

XML

Label

Element

Value

Prospectus:

rr_ProspectusTable

Document Type

dei_DocumentType

485BPOS

Document Period End Date

dei_DocumentPeriodEndDate

Aug. 31, 2018

Entity Registrant Name

dei_EntityRegistrantName

American Century California Tax Free & Municipal Funds

Central Index Key

dei_EntityCentralIndexKey

0000717316

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Dec. 28, 2018

Document Effective Date

dei_DocumentEffectiveDate

Jan. 01, 2019

Prospectus Date

rr_ProspectusDate

Jan. 01, 2019

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund

Prospectus:

rr_ProspectusTable

Risk/Return [Heading]

rr_RiskReturnHeading

California High-Yield Municipal Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks high current income that is exempt from federal and California income taxes.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy and hold shares of the fund. You may qualify for A Class sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in American Century Investments funds. More information about these and other discounts is available from your financial professional and in Calculation of Sales Charges on page 12 of the fund’s prospectus, Appendix A of the fund’s prospectus and Sales Charges in Appendix B of the statement of additional information.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

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 fund operating expenses or in the example, affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was52% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

52.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for A Class sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in American Century Investments funds. More information about these and other discounts is available from your financial professional and in Calculation of Sales Charges on page 12 of the fund’s prospectus, Appendix A of the fund’s prospectus and Sales Charges in Appendix B of the statement of additional information.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, that you earn a 5% return each year, and that the fund’s operating expenses remain the same. You may be required to pay brokerage commissions on your purchases of Investor, I or Y Class shares of the fund, which are not reflected in the example. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The fund invests in California municipal and other debt securities with an emphasis on high-yield securities. A high-yield security is one that has been rated below investment-grade, or determined by the investment advisor to be of similar quality. Under normal market conditions, the portfolio managers invest at least 80% of the fund’s net assets in municipal securities with income payments exempt from federal and California income taxes. Cities, counties and other municipalities in California and U.S. territories usually issue these securities for public projects, such as schools, roads, and water and sewer systems. Some of these investments are not necessarily exempt from the federal alternative minimum tax. 

The portfolio managers seek to invest in securities that will result in a high yield for the fund. To accomplish this, the portfolio managers buy securities that are rated below investment-grade, including so-called junk bonds and bonds that are in technical or monetary default. Issuers of these securities often have short financial histories or have questionable credit or have had and may continue to have problems making interest and principal payments. 

The portfolio managers also may buy unrated securities if they determine such securities meet the investment objectives of the fund. 

Although the fund invests primarily for income, it also employs techniques designed to realize capital appreciation. For example, the portfolio managers may select bonds with maturities and coupon rates that position the fund for potential capital appreciation for a variety of reasons, including their view on the direction of future interest-rate movements and the potential for a credit upgrade.

When determining whether to sell a security, the portfolio managers consider, among other things, current and anticipated changes in interest rates, the credit quality of a particular issuer, comparable alternatives, general market conditions and any other factor deemed relevant by the portfolio managers. 

Risk [Heading]

rr_RiskHeading

Principal Risks 

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Credit Risk – Debt securities, even investment-grade debt securities, are subject to credit risk. Credit risk is the risk that the inability or perceived inability of the issuer to make interest and principal payments will cause the value of the securities to decrease. As a result, the fund’s share price could also decrease. Changes in the credit rating of a debt security held by the fund could have a similar effect. The fund’s investments often have high credit risk, which helps the fund pursue a higher yield than more conservatively managed bond funds.

• Below Investment-Grade Securities Risk – Issuers of lower rated, high-yield securities are more vulnerable to real or perceived economic changes (such as an economic downturn or a prolonged period of rising interest rates), political changes, or adverse developments specific to the issuer. Adverse economic, political and other developments may be more likely to cause an issuer of low-quality bonds to default on its obligation to pay interest and principal due under its securities. The fund invests a significant part of its assets in securities rated below investment-grade or that are unrated, including bonds that are in technical or monetary default. By definition, the issuers of many of these securities have had and may continue to have problems making interest and principal payments.

• Interest Rate Risk – When interest rates change, the fund’s share value will be affected. Generally, the value of debt securities and the funds that hold them decline as interest rates rise. Because the fund typically invests in intermediate-term and long-term bonds, the fund’s interest rate risk is generally higher than for funds with shorter-weighted average maturities, such as money market and short-term bond funds. A period of rising interest rates may negatively affect the fund’s performance.

• California Economic Risk – The fund will be sensitive to events that affect California’s economy. Significant political or economic developments in California will likely impact virtually all municipal securities issued in the state. Because the fund invests principally in California municipal securities, it may have a higher level of risk than funds that invest in a larger universe of securities.

• Municipal Securities Risk – Because the fund invests principally in municipal securities, it will be sensitive to events that affect municipal markets, including legislative or political changes and the financial condition of the issuers of municipal securities. The fund may have a higher level of risk than funds that invest in a larger universe of securities.

• Liquidity Risk – The fund may also be subject to liquidity risk. During periods of market turbulence or unusually low trading activity, in order to meet redemptions, it may be necessary for the fund to sell securities at prices that could have an adverse effect on the fund’s share price. Changing regulatory and market conditions, including increases in interest rates and credit spreads may adversely affect the liquidity of the fund’s investments.

• Tax Risk – Some or all of the fund’s income may be subject to the federal alternative minimum tax. There is no guarantee that all of the fund’s income will remain exempt from federal or state income taxes. Income from municipal bonds held by a fund could be declared taxable because of unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or non-compliant conduct of a bond issuer. The fund may sell securities that lose their tax-exempt statuses at inopportune times, which may cause tax consequences or a decrease in the fund’s value.

• Market Risk – The value of securities owned by the fund may go up and down, sometimes rapidly or unpredictably.

• Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.

An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. 

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Fund Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. Because the Y Class does not have investment performance for a full calendar year, it is not included. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com. 

Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown. 

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. Because the Y Class does not have investment performance for a full calendar year, it is not included.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

americancentury.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown. 

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Highest Performance Quarter (3Q 2009): 12.08%Lowest Performance Quarter (4Q 2008): -9.36%

As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 0.35%.

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For the calendar year ended December 31, 2017

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns are shown only for Investor Class shares. After-tax returns for other share classes will vary.

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

After-tax returns are shown only for Investor Class shares. After-tax returns for other share classes will vary. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund | Bloomberg Barclays Municipal Bond Index

Prospectus:

rr_ProspectusTable

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses and taxes)

Label

rr_AverageAnnualReturnLabel

Bloomberg Barclays Municipal Bond Index    (reflects no deduction for fees, expenses and taxes)

1 Year

rr_AverageAnnualReturnYear01

5.45%

5 Years

rr_AverageAnnualReturnYear05

3.02%

10 Years

rr_AverageAnnualReturnYear10

4.45%

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund | S&P Municipal Bond California 50% Investment Grade/50% High Yield Index

Prospectus:

rr_ProspectusTable

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses and taxes)

Label

rr_AverageAnnualReturnLabel

S&P Municipal Bond California 50% Investment Grade/50% High Yield Index1    (reflects no deduction for fees, expenses and taxes)

^[1]

1 Year

rr_AverageAnnualReturnYear01

9.19%

^[1]

5 Years

rr_AverageAnnualReturnYear05

5.65%

^[1]

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund | Investor Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

BCHYX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum Account Fee

rr_MaximumAccountFee

$ 25

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.49%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.50%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 51

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

161

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

280

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 629

Annual Return 2008

rr_AnnualReturn2008

(13.52%)

Annual Return 2009

rr_AnnualReturn2009

20.43%

Annual Return 2010

rr_AnnualReturn2010

4.29%

Annual Return 2011

rr_AnnualReturn2011

11.02%

Annual Return 2012

rr_AnnualReturn2012

11.09%

Annual Return 2013

rr_AnnualReturn2013

(3.17%)

Annual Return 2014

rr_AnnualReturn2014

13.76%

Annual Return 2015

rr_AnnualReturn2015

5.08%

Annual Return 2016

rr_AnnualReturn2016

0.33%

Annual Return 2017

rr_AnnualReturn2017

8.48%

Year to Date Return, Label

rr_YearToDateReturnLabel

Investor Class year-to-date return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.35%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Performance Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

12.08%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Performance Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.36%)

Label

rr_AverageAnnualReturnLabel

Investor Class Return Before Taxes

1 Year

rr_AverageAnnualReturnYear01

8.48%

5 Years

rr_AverageAnnualReturnYear05

4.73%

10 Years

rr_AverageAnnualReturnYear10

5.37%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 1986

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund | Investor Class | After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

1 Year

rr_AverageAnnualReturnYear01

8.48%

5 Years

rr_AverageAnnualReturnYear05

4.73%

10 Years

rr_AverageAnnualReturnYear10

5.37%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 1986

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund | Investor Class | After Taxes on Distributions and Sales

Prospectus:

rr_ProspectusTable

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

1 Year

rr_AverageAnnualReturnYear01

6.41%

5 Years

rr_AverageAnnualReturnYear05

4.52%

10 Years

rr_AverageAnnualReturnYear10

5.16%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 30, 1986

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund | I Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

BCHIX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum Account Fee

rr_MaximumAccountFee

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.29%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.30%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 31

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

97

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

169

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 381

Label

rr_AverageAnnualReturnLabel

I Class Return Before Taxes

1 Year

rr_AverageAnnualReturnYear01

8.60%

5 Years

rr_AverageAnnualReturnYear05

4.92%

Since Inception

rr_AverageAnnualReturnSinceInception

6.27%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 01, 2010

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund | Y Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

ACYHX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum Account Fee

rr_MaximumAccountFee

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.26%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.27%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 28

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

87

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

152

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 344

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund | A Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

CAYAX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.50%

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

none

^[2]

Maximum Account Fee

rr_MaximumAccountFee

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.49%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.75%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 523

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

679

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

849

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,339

Label

rr_AverageAnnualReturnLabel

A Class Return Before Taxes

1 Year

rr_AverageAnnualReturnYear01

3.35%

5 Years

rr_AverageAnnualReturnYear05

3.51%

10 Years

rr_AverageAnnualReturnYear10

4.63%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 31, 2003

American Century California Tax-Free and Municipal Funds | California High-Yield Municipal Fund | C Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

CAYCX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

1.00%

Maximum Account Fee

rr_MaximumAccountFee

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.49%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

1.50%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 153

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

475

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

819

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,789

Label

rr_AverageAnnualReturnLabel

C Class Return Before Taxes

1 Year

rr_AverageAnnualReturnYear01

7.41%

5 Years

rr_AverageAnnualReturnYear05

3.69%

10 Years

rr_AverageAnnualReturnYear10

4.32%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jan. 31, 2003

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund

Prospectus:

rr_ProspectusTable

Risk/Return [Heading]

rr_RiskReturnHeading

California Intermediate-Term Tax-Free Bond FundCalifornia Tax-Free Money Market Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective 

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks safety of principal and high current income that is exempt from federal and California income taxes. 

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses you may pay if you buy and hold shares of the fund. You may qualify for A Class sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in American Century Investments funds. More information about these and other discounts is available from your financial professional and in Calculation of Sales Charges on page 12 of the fund’s prospectus, Appendix A of the fund’s prospectus and Sales Charges in Appendix B of the statement of additional information.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

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 fund operating expenses or in the example, affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 52%of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

52.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for A Class sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in American Century Investments funds. More information about these and other discounts is available from your financial professional and in Calculation of Sales Charges on page 12 of the fund’s prospectus, Appendix A of the fund’s prospectus and Sales Charges in Appendix B of the statement of additional information.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 100,000

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.

Expense Example by, Year, Caption [Text]

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The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, that you earn a 5% return each year, and that the fund’s operating expenses remain the same. You may be required to pay brokerage commissions on your purchases of Investor, I or Y Class shares of the fund, which are not reflected in the example. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal Investment Strategies

Strategy Narrative [Text Block]

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The portfolio managers primarily buy investment-grade debt securities and, under normal market conditions, will invest at least 80% of the fund’s net assets in debt securities that have interest payments exempt from federal and California income taxes. Cities, counties and other municipalities in California and U.S. territories, such as Puerto Rico, issue these securities.

The fund’s weighted average maturity will be not less than three years nor more than ten years. However, there is no maturity limit on individual securities. 

Although the fund invests primarily in investment-grade securities, up to 20% of the value of the fund’s net assets may be invested in below investment-grade securities, also known as junk bonds. The fund also may invest in securities which, while not rated, are determined by the portfolio managers to be of comparable credit quality to those rated below investment-grade. 

When determining whether to sell a security, portfolio managers consider, among other things, current and anticipated changes in interest rates, the credit quality of a particular issuer, comparable alternatives, general market conditions and any other factor deemed relevant by the portfolio managers. 

Risk [Heading]

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Principal Risks

Risk Narrative [Text Block]

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• Credit Risk – Debt securities, even investment-grade debt securities, are subject to credit risk. Credit risk is the risk that the inability or perceived inability of the issuer to make interest and principal payments will cause the value of the securities to decrease. As a result, the fund’s share price could also decrease. Changes in the credit rating of a debt security held by the fund could have a similar effect.

• Below Investment-Grade Securities Risk – Issuers of lower rated, high-yield securities are more vulnerable to real or perceived economic changes (such as an economic downturn or a prolonged period of rising interest rates), political changes or adverse developments specific to an issuer. These factors may be more likely to cause an issuer of low quality bonds to default on its obligations.

• Interest Rate Risk – Investments in debt securities are sensitive to interest rate changes. Generally, the value of debt securities and the funds that hold them decline as interest rates rise. The fund’s interest rate risk is moderate under normal market conditions, but it may fluctuate as the portfolio managers reposition the fund in response to changing market conditions. A period of rising interest rates may negatively affect the fund’s performance.

• California Economic Risk – The fund will be sensitive to events that affect California’s economy. Significant political or economic developments in California will likely impact virtually all municipal securities issued in the state. Because the fund invests principally in California municipal securities, it may have a higher level of risk than funds that invest in a larger universe of securities.

• Municipal Securities Risk – The fund invests principally in municipal securities, so it will be sensitive to events that affect municipal markets, including legislative or political changes and the financial condition of the issuers of municipal securities. By investing primarily in municipal securities, the fund may have a higher level of risk than funds that invest in a larger universe of securities.

• Loss of Tax Exemptions Risk – There is no guarantee that all of the fund’s income will be exempt from federal or state income taxes. Income from municipal bonds held by the fund could be declared taxable because of unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or non-compliant conduct of a bond issuer. The fund may sell securities that lose their tax-exempt statuses at inopportune times, which may cause tax consequences or a decrease in the fund’s value.

• Liquidity Risk – The fund may also be subject to liquidity risk. During periods of market turbulence or unusually low trading activity, to meet redemptions, it may be necessary for the fund to sell securities at prices that could have an adverse effect on the fund’s share price. Changing regulatory and market conditions, including increases in interest rates and credit spreads may adversely affect the liquidity of the fund’s investments.

• Market Risk – The value of securities owned by the fund may go up and down, sometimes rapidly or unpredictably.

• Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.

An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Risk Lose Money [Text]

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Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.

Risk Not Insured Depository Institution [Text]

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An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.

Bar Chart and Performance Table [Heading]

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Fund Performance 

Performance Narrative [Text Block]

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The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. Because the Y Class does not have investment performance for a full calendar year, it is not included. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.

Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. Because the Y Class does not have investment performance for a full calendar year, it is not included.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

americancentury.com

Performance Past Does Not Indicate Future [Text]

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The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

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Calendar Year Total Returns

Bar Chart Does Not Reflect Sales Loads [Text]

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Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.

Bar Chart Closing [Text Block]

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Highest Performance Quarter (3Q 2009): 6.57%Lowest Performance Quarter (4Q 2010): -4.11%

As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was -0.51%.

Performance Table Heading

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Average Annual Total Returns For the calendar year ended December 31, 2017

Performance Table Uses Highest Federal Rate

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After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

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Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.

Performance Table One Class of after Tax Shown [Text]

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After-tax returns are shown only for Investor Class shares. After-tax returns for other share classes will vary.

Performance Table Closing [Text Block]

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After-tax returns are shown only for Investor Class shares. After-tax returns for other share classes will vary. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund | Bloomberg Barclays 7 Year Municipal Bond Index

Prospectus:

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Index No Deduction for Fees, Expenses, Taxes [Text]

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 (reflects no deduction for fees, expenses and taxes)

Label

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Bloomberg Barclays 7 Year Municipal Bond Index    (reflects no deduction for fees, expenses and taxes)

1 Year

rr_AverageAnnualReturnYear01

4.49%

5 Years

rr_AverageAnnualReturnYear05

2.44%

10 Years

rr_AverageAnnualReturnYear10

4.30%

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund | S&P Intermediate Term California AMT-Free Municipal Bond Index

Prospectus:

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Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deduction for fees, expenses and taxes)

Label

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S&P Intermediate Term California AMT-Free Municipal Bond Index2    (reflects no deduction for fees, expenses and taxes)

^[3]

1 Year

rr_AverageAnnualReturnYear01

3.83%

^[3]

5 Years

rr_AverageAnnualReturnYear05

2.63%

^[3]

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund | Investor Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

BCITX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum Account Fee

rr_MaximumAccountFee

$ 25

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.46%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.47%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 48

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

151

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

264

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 592

Annual Return 2008

rr_AnnualReturn2008

(0.58%)

Annual Return 2009

rr_AnnualReturn2009

9.78%

Annual Return 2010

rr_AnnualReturn2010

2.09%

Annual Return 2011

rr_AnnualReturn2011

10.19%

Annual Return 2012

rr_AnnualReturn2012

5.94%

Annual Return 2013

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(1.31%)

Annual Return 2014

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6.21%

Annual Return 2015

rr_AnnualReturn2015

2.68%

Annual Return 2016

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(0.29%)

Annual Return 2017

rr_AnnualReturn2017

4.62%

Year to Date Return, Label

rr_YearToDateReturnLabel

Investor Class year-to-date return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

(0.51%)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Performance Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.57%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Performance Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(4.11%)

Label

rr_AverageAnnualReturnLabel

Investor Class Return Before Taxes

1 Year

rr_AverageAnnualReturnYear01

4.62%

5 Years

rr_AverageAnnualReturnYear05

2.34%

10 Years

rr_AverageAnnualReturnYear10

3.86%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 09, 1983

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund | Investor Class | After Taxes on Distributions

Prospectus:

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Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

1 Year

rr_AverageAnnualReturnYear01

4.62%

5 Years

rr_AverageAnnualReturnYear05

2.34%

10 Years

rr_AverageAnnualReturnYear10

3.86%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 09, 1983

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund | Investor Class | After Taxes on Distributions and Sales

Prospectus:

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Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

1 Year

rr_AverageAnnualReturnYear01

3.72%

5 Years

rr_AverageAnnualReturnYear05

2.37%

10 Years

rr_AverageAnnualReturnYear10

3.70%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 09, 1983

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund | I Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

BCTIX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum Account Fee

rr_MaximumAccountFee

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.26%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.27%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 28

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

87

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

152

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 344

Label

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I Class Return Before Taxes

1 Year

rr_AverageAnnualReturnYear01

4.83%

5 Years

rr_AverageAnnualReturnYear05

2.55%

Since Inception

rr_AverageAnnualReturnSinceInception

3.81%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 01, 2010

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund | Y Class

Prospectus:

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Trading Symbol

dei_TradingSymbol

ACYTX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

none

Maximum Account Fee

rr_MaximumAccountFee

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.23%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.24%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 25

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

77

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

135

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 306

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund | A Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

BCIAX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.50%

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

none

^[4]

Maximum Account Fee

rr_MaximumAccountFee

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.46%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.72%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 520

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

670

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

833

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,305

Label

rr_AverageAnnualReturnLabel

A Class1 Return Before Taxes

^[5]

1 Year

rr_AverageAnnualReturnYear01

(0.34%)

^[5]

5 Years

rr_AverageAnnualReturnYear05

1.16%

^[5]

10 Years

rr_AverageAnnualReturnYear10

3.12%

^[5]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 01, 2010

^[5]

American Century California Tax-Free and Municipal Funds | California Intermediate-Term Tax-Free Bond Fund | C Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

BCIYX

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum Deferred Sales Charge (as a percentage)

rr_MaximumDeferredSalesChargeOverOther

1.00%

Maximum Account Fee

rr_MaximumAccountFee

none

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.46%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

1.47%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 150

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

466

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

803

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,756

Label

rr_AverageAnnualReturnLabel

C Class1 Return Before Taxes

^[5]

1 Year

rr_AverageAnnualReturnYear01

3.58%

^[5]

5 Years

rr_AverageAnnualReturnYear05

1.35%

^[5]

10 Years

rr_AverageAnnualReturnYear10

2.84%

^[5]

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 01, 2010

^[5]

American Century California Tax-Free and Municipal Funds | California Tax-Free Money Market Fund

Prospectus:

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Objective [Heading]

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Investment Objective

Objective, Primary [Text Block]

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The fund seeks safety of principal and high current income that is exempt from federal and California income taxes.

Expense [Heading]

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Fees and Expenses

Expense Narrative [Text Block]

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The following table describes the fees and expenses you may pay if you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

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Shareholder Fees (fees paid directly from your investment)

Maximum Account Fee

rr_MaximumAccountFee

$ 25

Operating Expenses Caption [Text]

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Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Management Fees (as a percentage of Assets)

rr_ManagementFeesOverAssets

0.49%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses (as a percentage of Assets):

rr_OtherExpensesOverAssets

0.01%

Expenses (as a percentage of Assets)

rr_ExpensesOverAssets

0.50%

Expense Example [Heading]

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Example

Expense Example Narrative [Text Block]

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The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.

Expense Example by, Year, Caption [Text]

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The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, that you earn a 5% return each year, and that the fund’s operating expenses remain the same. You may be required to pay brokerage commissions on your purchases of Investor Class shares of the fund, which are not reflected in the example. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal Investment Strategies

Strategy Narrative [Text Block]

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The fund is a retail money market fund that invests in municipal money market securities. The securities purchased by the fund are subject to the maturity, quality, diversification, and other requirements of Rule 2a-7 under the Investment Company Act of 1940, as amended. Although the fund seeks to maintain a $1.00 share price, there is no guarantee it will be able to do so. Under normal market conditions, the fund invests in cash-equivalent, high-quality debt securities, at least 80% of which have interest payments exempt from federal and California income taxes. Cities, counties, other municipalities in California and U.S. territories may issue the securities. A high-quality debt security is one an independent rating agency rates in its top two credit quality categories or that the advisor determines to be of comparable credit quality.

Some of the securities in which the fund invests are guaranteed by certain U.S. government agencies or instrumentalities such as the Federal Home Loan Bank (FHLB), the Federal National Mortgage Association (Fannie Mae), and the Federal Home Loan Mortgage Corporation (Freddie Mac). Such securities are not guaranteed by the U.S. Treasury or supported by the full faith and credit of the U.S. government. However, these agencies are authorized to borrow from the U.S. Treasury to meet their obligations. 

When determining whether to buy or sell a security, portfolio managers may consider, among other things, current and anticipated changes in interest rates, issuer credit quality, comparable alternatives, diversification limits, general market conditions and any other factor deemed relevant by the portfolio managers.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

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• Low Yield – Because high-quality debt securities are among the safest securities available, the interest they pay is among the lowest for income-paying securities. Accordingly, the yield on this fund will likely be lower than the yield on funds that invest in lower-quality or longer-term securities.

• California Economic Risk – The fund will be sensitive to events that affect California’s economy. Significant political or economic developments in California will likely impact virtually all municipal securities issued in the state. Because the fund invests principally in California municipal securities, it may have a higher level of risk than funds that invest in a larger universe of securities.

• Municipal Securities Risk – Because the fund invests principally in municipal securities, it will be sensitive to events that affect municipal markets, including legislative or political changes and the financial condition of the issuers of municipal securities. By investing primarily in municipal securities, the fund may have a higher level of risk than funds that invest in a larger universe of securities.

• Interest Rate Risk – Interest rate risk means that the value of debt securities and the funds that hold them decline as interest rates rise. A period of rising interest rates may negatively affect the fund’s performance.

• Credit Risk – Credit risk is the risk that the inability or perceived inability of the issuer to make interest and principal payments will cause the value of the securities to decrease.

• Liquidity Risk – Liquidity risk means that during periods of market turbulence or unusually low trading activity, to meet redemptions it may be necessary for the fund to sell securities at prices that could have an adverse effect on the fund’s share price. Changing regulatory and market conditions may adversely affect the liquidity of the fund’s investments. If liquidity decreases too much, the fund may impose a fee on the sale of shares or temporarily suspend redemptions.

• Loss of Tax Exemptions Risk – There is no guarantee that all of the fund’s income will be exempt from federal or state income taxes. Income from municipal bonds held by the fund could be declared taxable because of unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or non-compliant conduct of a bond issuer. The fund may sell securities that lose their tax-exempt statuses at inopportune times, which may cause tax consequences or a decrease in the fund’s value.

• Principal Loss – You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund may impose a fee upon sale of your shares or may temporarily suspend your ability to sell shares if the fund’s liquidity falls below required minimums because of market conditions or other factors. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The fund’s sponsor has no legal obligation to provide financial support to the fund, and you should not expect that the sponsor will provide financial support to the fund at any time.

Risk Lose Money [Text]

rr_RiskLoseMoney

Principal Loss – You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund may impose a fee upon sale of your shares or may temporarily suspend your ability to sell shares if the fund’s liquidity falls below required minimums because of market conditions or other factors. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The fund’s sponsor has no legal obligation to provide financial support to the fund, and you should not expect that the sponsor will provide financial support to the fund at any time.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The fund’s sponsor has no legal obligation to provide financial support to the fund, and you should not expect that the sponsor will provide financial support to the fund at any time.

Bar Chart and Performance Table [Heading]

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Fund Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year. The fund’s past performance is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com. 

Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

americancentury.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund’s past performance is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Calendar Year Total Returns

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Highest Performance Quarter(1Q 2008): 0.58%Lowest Performance Quarter (1Q 2010): 0.00%

As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 0.65%.

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For the calendar year ended December 31, 2017

American Century California Tax-Free and Municipal Funds | California Tax-Free Money Market Fund | Investor Class

Prospectus:

rr_ProspectusTable

Trading Symbol

dei_TradingSymbol

BCTXX

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 51

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

161

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

280

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 629

Annual Return 2008

rr_AnnualReturn2008

1.92%

Annual Return 2009

rr_AnnualReturn2009

0.18%

Annual Return 2010

rr_AnnualReturn2010

0.01%

Annual Return 2011

rr_AnnualReturn2011

0.01%

Annual Return 2012

rr_AnnualReturn2012

0.01%

Annual Return 2013

rr_AnnualReturn2013

0.01%

Annual Return 2014

rr_AnnualReturn2014

0.01%

Annual Return 2015

rr_AnnualReturn2015

0.01%

Annual Return 2016

rr_AnnualReturn2016

0.13%

Annual Return 2017

rr_AnnualReturn2017

0.42%

Year to Date Return, Label

rr_YearToDateReturnLabel

Investor Class year-to-date return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

0.65%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Performance Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.58%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Performance Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

Label

rr_AverageAnnualReturnLabel

Investor Class

1 Year

rr_AverageAnnualReturnYear01

0.42%

5 Years

rr_AverageAnnualReturnYear05

0.11%

10 Years

rr_AverageAnnualReturnYear10

0.27%

[1] Effective December 31, 2017, the fund’s investment advisor selected a different benchmark for comparison purposes. The advisor believes the S&P Municipal Bond California 50% Investment Grade/50% High Yield Index is more reflective of the fund’s strategy. Because the S&P Municipal Bond California 50% Investment Grade/50% High Yield Index total return data is first available as of December 30, 2011, returns for the Bloomberg Barclays Municipal Bond Index are also shown to cover the 10 year period.

[2] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.

[3] Effective December 31, 2017, the fund’s investment advisor selected a different benchmark for comparison purposes. The advisor believes the S&P Intermediate Term California AMT-Free Municipal Bond Index is more reflective of the fund’s strategy. Because the S&P Intermediate Term California AMT-Free Municipal Bond Index total return data is first available as of June 30, 2010, returns for the Bloomberg Barclays 7 Year Municipal Bond Index are also shown to cover the 10 year period.

[4] Purchases of $1 million or more may be subject to a contingent deferred sales charge of 1.00% if the shares are redeemed within one year of the date of the purchase.

[5] Historical performance for A and C Classes prior to their inception is based on the performance of Investor Class shares. A and C Class performance has been adjusted to reflect differences in sales charges, if applicable, and expenses between classes.