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Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Aug. 31, 2011
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. 29, 2011
Document Effective Date dei_DocumentEffectiveDate Jan. 01, 2012
Prospectus Date rr_ProspectusDate Jan. 01, 2012
CALIFORNIA HIGH-YIELD MUNICIPAL FUND
  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading RISK/RETURN
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 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, as well as variations in charges that may apply to purchases of $1 million or more, is available from your financial professional and in Calculation of Sales Charges on page 12 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 37% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 37.00%
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for 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, as well as variations in charges that may apply to purchases of $1 million or more, is available from your financial professional and in Calculation of Sales Charges on page 12 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. 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 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 – The fund’s investments often have high credit risk, which helps the fund pursue a higher yield than more conservatively managed bond funds. Issuers of 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.
•
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 primarily 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 primarily 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.
•
Nondiversification – The fund is classified as nondiversified. A nondiversified fund may invest a greater percentage of its assets in a smaller number of securities than a diversified fund. This gives the managers the flexibility to hold large positions in a small number of securities. If so, a price change in any one of those securities may have a greater impact on the fund’s share price than would be the case in a diversified fund.

•
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 noncompliant conduct of a bond issuer.
•
Market Risk – The risk that 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 Nondiversified Status [Text] rr_RiskNondiversifiedStatus The fund is classified as nondiversified. A nondiversified fund may invest a greater percentage of its assets in a smaller number of securities than a diversified fund. This gives the managers the flexibility to hold large positions in a small number of securities. If so, a price change in any one of those securities may have a greater impact on the fund's share price than would be the case in a diversified 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. 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.
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 Annual 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, 2011, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 8.74%.
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2011
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 8.74%
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%)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2010
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. Because the Institutional Class does not have a full calendar year of performance, it is not included.
CALIFORNIA HIGH-YIELD MUNICIPAL FUND | Barclays Capital Municipal Bond Index (reflects no deduction for fees, expenses and taxes)
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 2.38%
5 Years rr_AverageAnnualReturnYear05 4.09%
10 Years rr_AverageAnnualReturnYear10 4.83%
CALIFORNIA HIGH-YIELD MUNICIPAL FUND | INVESTOR CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee 25
Management Fee rr_ManagementFeesOverAssets 0.50%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.51%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 52
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 164
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 286
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 641
Annual Return 2001 rr_AnnualReturn2001 5.02%
Annual Return 2002 rr_AnnualReturn2002 9.10%
Annual Return 2003 rr_AnnualReturn2003 5.72%
Annual Return 2004 rr_AnnualReturn2004 6.73%
Annual Return 2005 rr_AnnualReturn2005 6.80%
Annual Return 2006 rr_AnnualReturn2006 5.78%
Annual Return 2007 rr_AnnualReturn2007 (0.33%)
Annual Return 2008 rr_AnnualReturn2008 (13.52%)
Annual Return 2009 rr_AnnualReturn2009 20.43%
Annual Return 2010 rr_AnnualReturn2010 4.29%
1 Year rr_AverageAnnualReturnYear01 4.29%
5 Years rr_AverageAnnualReturnYear05 2.75%
10 Years rr_AverageAnnualReturnYear10 4.69%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 30, 1986
CALIFORNIA HIGH-YIELD MUNICIPAL FUND | INVESTOR CLASS | After Taxes on Distributions
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 4.29%
5 Years rr_AverageAnnualReturnYear05 2.75%
10 Years rr_AverageAnnualReturnYear10 4.69%
CALIFORNIA HIGH-YIELD MUNICIPAL FUND | INVESTOR CLASS | After Taxes on Distributions and Sales
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 4.61%
5 Years rr_AverageAnnualReturnYear05 3.07%
10 Years rr_AverageAnnualReturnYear10 4.78%
CALIFORNIA HIGH-YIELD MUNICIPAL FUND | INSTITUTIONAL CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee none
Management Fee rr_ManagementFeesOverAssets 0.30%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.31%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 32
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 100
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 175
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 394
CALIFORNIA HIGH-YIELD MUNICIPAL FUND | A CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.50%
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee none
Management Fee rr_ManagementFeesOverAssets 0.50%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.76%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 524
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 682
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 854
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,350
1 Year rr_AverageAnnualReturnYear01 (0.63%)
5 Years rr_AverageAnnualReturnYear05 1.55%
Since Inception rr_AverageAnnualReturnSinceInception 3.35%
Inception Date rr_AverageAnnualReturnInceptionDate Jan. 31, 2003
CALIFORNIA HIGH-YIELD MUNICIPAL FUND | C CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee none
Management Fee rr_ManagementFeesOverAssets 0.50%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.51%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 154
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 478
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 824
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,800
1 Year rr_AverageAnnualReturnYear01 3.25%
5 Years rr_AverageAnnualReturnYear05 1.72%
Since Inception rr_AverageAnnualReturnSinceInception 3.21%
Inception Date rr_AverageAnnualReturnInceptionDate Jan. 31, 2003
CALIFORNIA INTERMEDIATE-TERM TAX-FREE BOND FUND
  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading RISK/RETURN
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 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, as well as variations in charges that may apply to purchases of $1 million or more, is available from your financial professional and in Calculation of Sales Charges on page 12 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 49% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 49.00%
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for 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, as well as variations in charges that may apply to purchases of $1 million or more, is available from your financial professional and in Calculation of Sales Charges on page 12 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. 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 portfolio managers primarily buy investment-grade debt securities and, under normal market conditions, will invest at least 80% of the fund’s 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 (BB and below). 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] 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.
•
Interest Rate Risk – Investments in debt securities are also 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.
•
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 primarily 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 primarily 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.
•
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 noncompliant conduct of a bond issuer.
•
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.
•
Market Risk – The risk that 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. 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.
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 Annual 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): 6.57%
Lowest Performance Quarter (4Q 2010): -4.11%

As of September 30, 2011, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 7.77%.
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2011
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 7.77%
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%)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2010
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 Closing [Text Block] rr_PerformanceTableClosingTextBlock
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. Because the Institutional Class does not have a full calendar year of performance, it is not included.
CALIFORNIA INTERMEDIATE-TERM TAX-FREE BOND FUND | Barclays Capital 7 Year Municipal Bond Index (reflects no deduction for fees, expenses and taxes)
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 4.63%
5 Years rr_AverageAnnualReturnYear05 5.17%
10 Years rr_AverageAnnualReturnYear10 5.15%
CALIFORNIA INTERMEDIATE-TERM TAX-FREE BOND FUND | INVESTOR CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee 25
Management Fee rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.48%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 49
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 154
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 269
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 604
Annual Return 2001 rr_AnnualReturn2001 4.35%
Annual Return 2002 rr_AnnualReturn2002 8.80%
Annual Return 2003 rr_AnnualReturn2003 3.23%
Annual Return 2004 rr_AnnualReturn2004 2.80%
Annual Return 2005 rr_AnnualReturn2005 2.25%
Annual Return 2006 rr_AnnualReturn2006 4.00%
Annual Return 2007 rr_AnnualReturn2007 2.64%
Annual Return 2008 rr_AnnualReturn2008 (0.58%)
Annual Return 2009 rr_AnnualReturn2009 9.78%
Annual Return 2010 rr_AnnualReturn2010 2.09%
1 Year rr_AverageAnnualReturnYear01 2.09%
5 Years rr_AverageAnnualReturnYear05 3.53%
10 Years rr_AverageAnnualReturnYear10 3.89%
CALIFORNIA INTERMEDIATE-TERM TAX-FREE BOND FUND | INVESTOR CLASS | After Taxes on Distributions
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 2.09%
5 Years rr_AverageAnnualReturnYear05 3.53%
10 Years rr_AverageAnnualReturnYear10 3.86%
CALIFORNIA INTERMEDIATE-TERM TAX-FREE BOND FUND | INVESTOR CLASS | After Taxes on Distributions and Sales
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 2.66%
5 Years rr_AverageAnnualReturnYear05 3.60%
10 Years rr_AverageAnnualReturnYear10 3.90%
CALIFORNIA INTERMEDIATE-TERM TAX-FREE BOND FUND | INSTITUTIONAL CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee none
Management Fee rr_ManagementFeesOverAssets 0.27%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.28%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 29
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 90
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 158
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 356
CALIFORNIA INTERMEDIATE-TERM TAX-FREE BOND FUND | A CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.50%
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee none
Management Fee rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.73%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 521
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 673
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 838
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,316
1 Year rr_AverageAnnualReturnYear01 (2.70%) [1]
5 Years rr_AverageAnnualReturnYear05 2.32% [1]
10 Years rr_AverageAnnualReturnYear10 3.16% [1]
CALIFORNIA INTERMEDIATE-TERM TAX-FREE BOND FUND | C CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee none
Management Fee rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.48%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 151
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 469
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 809
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,767
1 Year rr_AverageAnnualReturnYear01 1.15% [1]
5 Years rr_AverageAnnualReturnYear05 2.51% [1]
10 Years rr_AverageAnnualReturnYear10 2.87% [1]
CALIFORNIA LONG-TERM TAX-FREE FUND
  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading RISK/RETURN
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 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, as well as variations in charges that may apply to purchases of $1 million or more, is available from your financial professional and in Calculation of Sales Charges on page 12 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 63% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 63.00%
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for 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, as well as variations in charges that may apply to purchases of $1 million or more, is available from your financial professional and in Calculation of Sales Charges on page 12 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. 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 portfolio managers primarily buy investment-grade debt securities. Under normal market conditions, the portfolio managers invest at least 80% of the fund’s assets in debt securities with interest payments exempt from federal and California income taxes. Cities, counties and other municipalities in California and U.S. territories, such as Puerto Rico, usually issue these securities. The fund will typically invest in California municipal securities with maturities of seven or more years. Under normal market conditions, the fund will maintain a weighted average maturity of ten or more years.

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. The fund may also invest in securities which, while not rated, are determined by the investment advisor 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] 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.
•
Interest Rate Risk – Investments in debt securities are also sensitive to interest rate changes. Generally, the value of debt securities and the funds that hold them decline as interest rates rise. Because this fund has a longer weighted average maturity, it is likely to be more sensitive to interest rate changes.
•
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 primarily 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 primarily in municipal securities and 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 noncompliant conduct of a bond issuer.
•
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.
•
Market Risk – The risk that 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. 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.
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 Annual 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): 9.36%
Lowest Performance Quarter (4Q 2010): -5.52%

As of September 30, 2011, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 9.36%.
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2011
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 9.36%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.36%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2010
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.52%)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2010
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 The 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
The 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. Because the Institutional Class does not have a full calendar year of performance, it is not included.
CALIFORNIA LONG-TERM TAX-FREE FUND | Barclays Capital Municipal Bond Index (reflects no deduction for fees, expenses and taxes)
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 2.38%
5 Years rr_AverageAnnualReturnYear05 4.09%
10 Years rr_AverageAnnualReturnYear10 4.83%
CALIFORNIA LONG-TERM TAX-FREE FUND | INVESTOR CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee 25
Management Fee rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.48%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 49
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 154
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 269
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 604
Annual Return 2001 rr_AnnualReturn2001 4.23%
Annual Return 2002 rr_AnnualReturn2002 8.69%
Annual Return 2003 rr_AnnualReturn2003 4.51%
Annual Return 2004 rr_AnnualReturn2004 4.10%
Annual Return 2005 rr_AnnualReturn2005 3.32%
Annual Return 2006 rr_AnnualReturn2006 4.88%
Annual Return 2007 rr_AnnualReturn2007 1.59%
Annual Return 2008 rr_AnnualReturn2008 (6.03%)
Annual Return 2009 rr_AnnualReturn2009 13.74%
Annual Return 2010 rr_AnnualReturn2010 1.61%
1 Year rr_AverageAnnualReturnYear01 1.61%
5 Years rr_AverageAnnualReturnYear05 2.96%
10 Years rr_AverageAnnualReturnYear10 3.95%
Inception Date rr_AverageAnnualReturnInceptionDate Nov. 09, 1983
CALIFORNIA LONG-TERM TAX-FREE FUND | INVESTOR CLASS | After Taxes on Distributions
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 1.61%
5 Years rr_AverageAnnualReturnYear05 2.95%
10 Years rr_AverageAnnualReturnYear10 3.91%
CALIFORNIA LONG-TERM TAX-FREE FUND | INVESTOR CLASS | After Taxes on Distributions and Sales
  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 2.65%
5 Years rr_AverageAnnualReturnYear05 3.20%
10 Years rr_AverageAnnualReturnYear10 4.05%
CALIFORNIA LONG-TERM TAX-FREE FUND | INSTITUTIONAL CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee none
Management Fee rr_ManagementFeesOverAssets 0.27%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.28%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 29
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 90
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 158
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 356
CALIFORNIA LONG-TERM TAX-FREE FUND | A CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.50%
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee none
Management Fee rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.73%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 521
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 673
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 838
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,316
1 Year rr_AverageAnnualReturnYear01 (3.24%)
Since Inception rr_AverageAnnualReturnSinceInception 1.13%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 28, 2007
CALIFORNIA LONG-TERM TAX-FREE FUND | C CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of the original offering price or redemption proceeds) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee none
Management Fee rr_ManagementFeesOverAssets 0.47%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.48%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 151
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 469
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 809
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,767
1 Year rr_AverageAnnualReturnYear01 0.60%
Since Inception rr_AverageAnnualReturnSinceInception 1.79%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 28, 2007
CALIFORNIA TAX-FREE MONEY MARKET FUND
  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading RISK/RETURN
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.
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)
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. 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 is a money market fund and invests in municipal money market securities. Under normal market conditions, the portfolio managers invest in high-quality, very short-term debt securities issued by cities, counties and other municipalities in California and U.S. territories, such as Puerto Rico, at least 80% of which have interest payments exempt from federal and California income taxes. A high-quality debt security is one that has been rated by an independent rating agency in its top two credit quality categories or determined by the advisor 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 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] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
Low Interest – 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 longer-term or lower-quality 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 primarily 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 primarily 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, Credit and Liquidity Risks – Even though the fund’s investments are designed to minimize credit, interest rate and liquidity risk, the fund is still subject to some degree of 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. Interest rate risk means that the value of debt securities and funds that hold them decline as interest rates rise. Liquidity risk means that 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.
•
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 noncompliant conduct of a bond issuer.
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Principal Loss – 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. Although the fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in it.
Risk Lose Money [Text] rr_RiskLoseMoney Although the fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in it.
Risk Money Market Fund [Text] rr_RiskMoneyMarketFund 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. Although the fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in it.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution Principal Loss - 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. 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 Annual 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 2007): 0.82%

Lowest Performance Quarter (3Q 2009): 0.00%

As of September 30, 2011, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 0.01%.
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2011
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 0.01%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2007
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 0.82%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn 0.00%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2010
CALIFORNIA TAX-FREE MONEY MARKET FUND | INVESTOR CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Annual Account Maintenance Fee (waived if eligible investments total at least $10,000) rr_MaximumAccountFee 25
Management Fee rr_ManagementFeesOverAssets 0.49%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.01%
Total Annual Fund Operating Expenses 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 2001 rr_AnnualReturn2001 2.20%
Annual Return 2002 rr_AnnualReturn2002 1.06%
Annual Return 2003 rr_AnnualReturn2003 0.60%
Annual Return 2004 rr_AnnualReturn2004 0.76%
Annual Return 2005 rr_AnnualReturn2005 1.94%
Annual Return 2006 rr_AnnualReturn2006 2.95%
Annual Return 2007 rr_AnnualReturn2007 3.22%
Annual Return 2008 rr_AnnualReturn2008 1.92%
Annual Return 2009 rr_AnnualReturn2009 0.18%
Annual Return 2010 rr_AnnualReturn2010 0.01%
1 Year rr_AverageAnnualReturnYear01 0.01%
5 Years rr_AverageAnnualReturnYear05 1.65%
10 Years rr_AverageAnnualReturnYear10 1.48%
[1] 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.