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American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice In Retirement Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The fund seeks current income.
Objective, Secondary [Text Block] rr_ObjectiveSecondaryTextBlock Capital appreciation is a secondary objective.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 14% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 14.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice In Retirement Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)45.0 %
U.S. Equity33.0 %
International Equity11.0 %
Real Estate1.0 %
Fixed-Income Securities (Bond Funds)47.3 %
Short-Term Investments (Short-Term Funds)7.7 %
The neutral mix of One Choice In Retirement Portfolio is expected to remain fixed over time. The fund is generally intended for investors near to, at, or in retirement and who likely are no longer making new investments in the fund. The fund is designed for investors who plan to gradually withdraw the value of their account after retirement. The fund assumes a retirement age of 65 and may not be appropriate for an investor retiring at an age well before or after age 65.
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice In Retirement Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date Retirement Income Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date Retirement Income Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (2Q 2020): 10.73% Lowest Performance Quarter (1Q 2020): -10.25%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 9.38%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date Retirement Income Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock 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.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | High-Yield Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock High-Yield Securities Risk – Some of the underlying funds may invest in high-yield securities, which are considered to have speculative characteristics and are more likely to be negatively affected by changes in economic conditions.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | S&P Target Date Retirement Income Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date Retirement Income Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 10.35%
5 Years rr_AverageAnnualReturnYear05 4.90%
10 Years rr_AverageAnnualReturnYear10 3.98%
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [1]
Label rr_AverageAnnualReturnLabel Russell 3000® Index3(reflects no deduction for fees, expenses or taxes) [1]
1 Year rr_AverageAnnualReturnYear01 25.96% [1]
5 Years rr_AverageAnnualReturnYear05 15.16% [1]
10 Years rr_AverageAnnualReturnYear10 11.48% [1]
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [1]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index3(reflects no deduction for fees, expenses or taxes) [1]
1 Year rr_AverageAnnualReturnYear01 5.53% [1]
5 Years rr_AverageAnnualReturnYear05 1.10% [1]
10 Years rr_AverageAnnualReturnYear10 1.81% [1]
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARTOX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.78% [2]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.80%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [3]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.76%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 78
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 252
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 441
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 986
Annual Return 2014 rr_AnnualReturn2014 6.20%
Annual Return 2015 rr_AnnualReturn2015 (1.69%)
Annual Return 2016 rr_AnnualReturn2016 5.91%
Annual Return 2017 rr_AnnualReturn2017 10.21%
Annual Return 2018 rr_AnnualReturn2018 (4.16%)
Annual Return 2019 rr_AnnualReturn2019 15.85%
Annual Return 2020 rr_AnnualReturn2020 10.71%
Annual Return 2021 rr_AnnualReturn2021 8.89%
Annual Return 2022 rr_AnnualReturn2022 (13.22%)
Annual Return 2023 rr_AnnualReturn2023 11.07%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 9.38%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.73%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (10.25%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.07%
5 Years rr_AverageAnnualReturnYear05 6.13%
10 Years rr_AverageAnnualReturnYear10 4.63%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 9.65%
5 Years rr_AverageAnnualReturnYear05 4.37%
10 Years rr_AverageAnnualReturnYear10 3.14%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 7.02%
5 Years rr_AverageAnnualReturnYear05 4.42%
10 Years rr_AverageAnnualReturnYear10 3.27%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ATTIX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60% [2]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.62%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [3]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.56%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 57
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 193
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 340
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 769
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.29%
5 Years rr_AverageAnnualReturnYear05 6.34%
10 Years rr_AverageAnnualReturnYear10 4.84%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARTAX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [4]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.78% [2]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.05%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [3]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.01%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 672
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 887
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,118
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,780
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 4.42%
5 Years rr_AverageAnnualReturnYear05 4.60%
10 Years rr_AverageAnnualReturnYear10 3.75%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ATTCX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.78% [2]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.80%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [3]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.76%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 179
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 563
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 972
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,914
Label rr_AverageAnnualReturnLabel C Class1 Return Before Taxes [5]
1 Year rr_AverageAnnualReturnYear01 9.98% [5]
5 Years rr_AverageAnnualReturnYear05 5.07% [5]
10 Years rr_AverageAnnualReturnYear10 3.74% [5]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [5]
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARSRX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.78% [2]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.30%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [3]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.26%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 129
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 409
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 710
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,564
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.54%
5 Years rr_AverageAnnualReturnYear05 5.59%
10 Years rr_AverageAnnualReturnYear10 4.11%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARDTX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.49% [2]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.51%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%) [3]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.41%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 42
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 154
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 276
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 631
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.38%
5 Years rr_AverageAnnualReturnYear05 6.50%
10 Years rr_AverageAnnualReturnYear10 4.97% [6]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2025 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 13% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 13.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice 2025 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)45.0 %
U.S. Equity33.0 %
International Equity11.0 %
Real Estate1.0 %
Fixed-Income Securities (Bond Funds)47.3 %
Short-Term Investments (Short-Term Funds)7.7 %
The target date in the fund name (2025) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The fund assumes a retirement age of 65 and may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. As the target date approaches, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. By the time the fund reaches its target date, the neutral mix will become fixed and match that of One Choice In Retirement Portfolio, which is currently 45% stock funds, 47.3% bond funds and 7.7% short-term funds. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.

Glide path.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice 2025 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2025 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2025 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (2Q 2020): 11.78% Lowest Performance Quarter (1Q 2020): -11.47%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 9.51%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2025 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock 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.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | High-Yield Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock High-Yield Securities Risk – Some of the underlying funds may invest in high-yield securities, which are considered to have speculative characteristics and are more likely to be negatively affected by changes in economic conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | S&P Target Date To 2025 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2025 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 12.44%
5 Years rr_AverageAnnualReturnYear05 6.78%
10 Years rr_AverageAnnualReturnYear10 5.35%
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [7]
Label rr_AverageAnnualReturnLabel Russell 3000® Index3(reflects no deduction for fees, expenses or taxes) [7]
1 Year rr_AverageAnnualReturnYear01 25.96% [7]
5 Years rr_AverageAnnualReturnYear05 15.16% [7]
10 Years rr_AverageAnnualReturnYear10 11.48% [7]
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [7]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index3(reflects no deduction for fees, expenses or taxes) [7]
1 Year rr_AverageAnnualReturnYear01 5.53% [7]
5 Years rr_AverageAnnualReturnYear05 1.10% [7]
10 Years rr_AverageAnnualReturnYear10 1.81% [7]
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARWIX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.78% [8]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.80%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [9]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.78%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 80
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 254
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 443
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 988
Annual Return 2014 rr_AnnualReturn2014 6.87%
Annual Return 2015 rr_AnnualReturn2015 (1.52%)
Annual Return 2016 rr_AnnualReturn2016 6.20%
Annual Return 2017 rr_AnnualReturn2017 12.27%
Annual Return 2018 rr_AnnualReturn2018 (4.96%)
Annual Return 2019 rr_AnnualReturn2019 17.37%
Annual Return 2020 rr_AnnualReturn2020 11.40%
Annual Return 2021 rr_AnnualReturn2021 9.38%
Annual Return 2022 rr_AnnualReturn2022 (13.82%)
Annual Return 2023 rr_AnnualReturn2023 11.25%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 9.51%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.78%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (11.47%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.25%
5 Years rr_AverageAnnualReturnYear05 6.52%
10 Years rr_AverageAnnualReturnYear10 5.04%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 9.94%
5 Years rr_AverageAnnualReturnYear05 4.81%
10 Years rr_AverageAnnualReturnYear10 3.51%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 7.12%
5 Years rr_AverageAnnualReturnYear05 4.79%
10 Years rr_AverageAnnualReturnYear10 3.62%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARWFX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60% [8]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.62%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [9]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.58%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 59
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 195
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 342
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 771
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.47%
5 Years rr_AverageAnnualReturnYear05 6.73%
10 Years rr_AverageAnnualReturnYear10 5.25%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARWAX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [10]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.78% [8]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.05%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [9]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.03%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 674
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 889
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,120
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,782
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 4.58%
5 Years rr_AverageAnnualReturnYear05 5.00%
10 Years rr_AverageAnnualReturnYear10 4.17%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARWCX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.78% [8]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.80%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [9]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.78%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 181
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 565
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 974
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,916
Label rr_AverageAnnualReturnLabel C Class1 Return Before Taxes [11]
1 Year rr_AverageAnnualReturnYear01 10.11% [11]
5 Years rr_AverageAnnualReturnYear05 5.45% [11]
10 Years rr_AverageAnnualReturnYear10 4.16% [11]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [11]
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARWRX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.78% [8]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.30%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [9]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.28%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 131
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 411
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 712
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,565
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.69%
5 Years rr_AverageAnnualReturnYear05 6.00%
10 Years rr_AverageAnnualReturnYear10 4.52%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARWDX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.49% [8]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.51%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.08%) [9]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.43%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 44
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 156
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 278
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 633
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.58%
5 Years rr_AverageAnnualReturnYear05 6.88%
10 Years rr_AverageAnnualReturnYear10 5.40% [12]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2030 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 15% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 15.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice 2030 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)50.0 %
U.S. Equity36.0 %
International Equity12.8 %
Real Estate1.2 %
Fixed-Income Securities (Bond Funds)45.2 %
Short-Term Investments (Short-Term Funds)4.8 %
The target date in the fund name (2030) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The fund assumes a retirement age of 65 and may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. As the target date approaches, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. By the time the fund reaches its target date, the neutral mix will become fixed and match that of One Choice In Retirement Portfolio, which is currently 45% stock funds, 47.3% bond funds and 7.7% short-term funds. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.

Glide path.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice 2030 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2030 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2030 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (2Q 2020): 13.00% Lowest Performance Quarter (1Q 2020): -12.63%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 10.08%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2030 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price. Investing in securities of companies located in emerging market countries is generally riskier than investing in securities of companies located in developed foreign countries.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | High-Yield Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock High-Yield Securities Risk – Some of the underlying funds may invest in high-yield securities, which are considered to have speculative characteristics and are more likely to be negatively affected by changes in economic conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | S&P Target Date To 2030 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2030 Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 14.43%
5 Years rr_AverageAnnualReturnYear05 7.90%
10 Years rr_AverageAnnualReturnYear10 6.01%
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [13]
Label rr_AverageAnnualReturnLabel Russell 3000® Index3(reflects no deduction for fees, expenses or taxes) [13]
1 Year rr_AverageAnnualReturnYear01 25.96% [13]
5 Years rr_AverageAnnualReturnYear05 15.16% [13]
10 Years rr_AverageAnnualReturnYear10 11.48% [13]
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [13]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index3(reflects no deduction for fees, expenses or taxes) [13]
1 Year rr_AverageAnnualReturnYear01 5.53% [13]
5 Years rr_AverageAnnualReturnYear05 1.10% [13]
10 Years rr_AverageAnnualReturnYear10 1.81% [13]
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARCVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [14]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.82%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [15]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.80%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 82
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 260
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 454
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,012
Annual Return 2014 rr_AnnualReturn2014 7.22%
Annual Return 2015 rr_AnnualReturn2015 (1.37%)
Annual Return 2016 rr_AnnualReturn2016 6.41%
Annual Return 2017 rr_AnnualReturn2017 13.51%
Annual Return 2018 rr_AnnualReturn2018 (5.53%)
Annual Return 2019 rr_AnnualReturn2019 18.57%
Annual Return 2020 rr_AnnualReturn2020 12.61%
Annual Return 2021 rr_AnnualReturn2021 10.10%
Annual Return 2022 rr_AnnualReturn2022 (14.74%)
Annual Return 2023 rr_AnnualReturn2023 12.07%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 10.08%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 13.00%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.63%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.07%
5 Years rr_AverageAnnualReturnYear05 7.03%
10 Years rr_AverageAnnualReturnYear10 5.42%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 11.06%
5 Years rr_AverageAnnualReturnYear05 5.34%
10 Years rr_AverageAnnualReturnYear10 3.92%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 7.39%
5 Years rr_AverageAnnualReturnYear05 5.20%
10 Years rr_AverageAnnualReturnYear10 3.93%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARCSX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62% [14]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.64%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [15]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.60%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 61
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 201
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 353
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 795
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.31%
5 Years rr_AverageAnnualReturnYear05 7.26%
10 Years rr_AverageAnnualReturnYear10 5.63%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARCMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [16]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [14]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.07%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [15]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.05%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 676
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 894
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,130
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,804
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 5.39%
5 Years rr_AverageAnnualReturnYear05 5.52%
10 Years rr_AverageAnnualReturnYear10 4.53%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARWOX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [14]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.82%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [15]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.80%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 183
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 571
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 984
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,937
Label rr_AverageAnnualReturnLabel C Class1 Return Before Taxes [17]
1 Year rr_AverageAnnualReturnYear01 10.94% [17]
5 Years rr_AverageAnnualReturnYear05 5.97% [17]
10 Years rr_AverageAnnualReturnYear10 4.52% [17]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [17]
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARCRX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [14]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.32%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [15]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.30%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 133
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 417
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 722
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,588
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.53%
5 Years rr_AverageAnnualReturnYear05 6.50%
10 Years rr_AverageAnnualReturnYear10 4.89%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARCUX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.50% [14]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.52%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [15]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.45%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 46
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 160
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 284
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 646
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.47%
5 Years rr_AverageAnnualReturnYear05 7.41%
10 Years rr_AverageAnnualReturnYear10 5.77% [18]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2035 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 15% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 15.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice 2035 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)55.0 %
U.S. Equity39.0 %
International Equity14.6 %
Real Estate1.4 %
Fixed-Income Securities (Bond Funds)42.3 %
Short-Term Investments (Short-Term Funds)2.7 %
The target date in the fund name (2035) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The fund assumes a retirement age of 65 and may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. As the target date approaches, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. By the time the fund reaches its target date, the neutral mix will become fixed and match that of One Choice In Retirement Portfolio, which is currently 45% stock funds, 47.3% bond funds and 7.7% short-term funds. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.

Glide path.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice 2035 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2035 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2035 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (2Q 2020): 14.34% Lowest Performance Quarter (1Q 2020): -13.99%

As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 10.77%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2035 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Real Estate Investing Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Real Estate Investing Risk - An investment in the fund may be subject to many of the same risks as a direct investment in real estate. These risks include changes in economic conditions, interest rates, property values, property tax increases, overbuilding and increased competition, environmental contamination, zoning and natural disasters. This is due to the fact that the value of the fund’s investments may be affected by the value of the real estate owned by the companies in which it invests.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | S&P Target Date To 2035 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2035 Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 16.48%
5 Years rr_AverageAnnualReturnYear05 8.98%
10 Years rr_AverageAnnualReturnYear10 6.59%
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [19]
Label rr_AverageAnnualReturnLabel Russell 3000® Index3(reflects no deduction for fees, expenses or taxes) [19]
1 Year rr_AverageAnnualReturnYear01 25.96% [19]
5 Years rr_AverageAnnualReturnYear05 15.16% [19]
10 Years rr_AverageAnnualReturnYear10 11.48% [19]
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [19]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index3(reflects no deduction for fees, expenses or taxes) [19]
1 Year rr_AverageAnnualReturnYear01 5.53% [19]
5 Years rr_AverageAnnualReturnYear05 1.10% [19]
10 Years rr_AverageAnnualReturnYear10 1.81% [19]
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARYIX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [20]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.85%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [21]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.83%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 85
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 270
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 470
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,047
Annual Return 2014 rr_AnnualReturn2014 7.56%
Annual Return 2015 rr_AnnualReturn2015 (1.23%)
Annual Return 2016 rr_AnnualReturn2016 6.54%
Annual Return 2017 rr_AnnualReturn2017 14.71%
Annual Return 2018 rr_AnnualReturn2018 (6.10%)
Annual Return 2019 rr_AnnualReturn2019 20.01%
Annual Return 2020 rr_AnnualReturn2020 13.86%
Annual Return 2021 rr_AnnualReturn2021 10.80%
Annual Return 2022 rr_AnnualReturn2022 (15.62%)
Annual Return 2023 rr_AnnualReturn2023 12.86%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 10.77%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 14.34%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.99%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.86%
5 Years rr_AverageAnnualReturnYear05 7.59%
10 Years rr_AverageAnnualReturnYear10 5.80%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 11.93%
5 Years rr_AverageAnnualReturnYear05 5.95%
10 Years rr_AverageAnnualReturnYear10 4.28%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 7.89%
5 Years rr_AverageAnnualReturnYear05 5.68%
10 Years rr_AverageAnnualReturnYear10 4.25%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARLIX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.64% [20]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.66%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [21]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.63%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 65
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 209
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 365
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 820
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.08%
5 Years rr_AverageAnnualReturnYear05 7.80%
10 Years rr_AverageAnnualReturnYear10 6.01%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARYAX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [22]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [20]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.10%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [21]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.08%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 679
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 903
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,145
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,836
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 6.11%
5 Years rr_AverageAnnualReturnYear05 6.06%
10 Years rr_AverageAnnualReturnYear10 4.91%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARLCX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [20]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.85%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [21]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.83%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 186
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 581
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,000
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,970
Label rr_AverageAnnualReturnLabel C Class1 Return Before Taxes [23]
1 Year rr_AverageAnnualReturnYear01 11.74% [23]
5 Years rr_AverageAnnualReturnYear05 6.51% [23]
10 Years rr_AverageAnnualReturnYear10 4.90% [23]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [23]
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARYRX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [20]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.35%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [21]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.33%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 136
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 426
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 738
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,621
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.29%
5 Years rr_AverageAnnualReturnYear05 7.05%
10 Years rr_AverageAnnualReturnYear10 5.27%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARLDX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52% [20]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.54%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [21]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.48%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 49
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 167
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 296
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 672
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.26%
5 Years rr_AverageAnnualReturnYear05 7.97%
10 Years rr_AverageAnnualReturnYear10 6.16% [24]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2040 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 14% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 14.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice 2040 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)61.3 %
U.S. Equity42.8 %
International Equity16.8 %
Real Estate1.7 %
Fixed-Income Securities (Bond Funds)37.6 %
Short-Term Investments (Short-Term Funds)1.1 %
The target date in the fund name (2040) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The fund assumes a retirement age of 65 and may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. As the target date approaches, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. By the time the fund reaches its target date, the neutral mix will become fixed and match that of One Choice In Retirement Portfolio, which is currently 45% stock funds, 47.3% bond funds and 7.7% short-term funds. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.

Glide path.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice 2040 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2040 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2040 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (2Q 2020): 15.58% Lowest Performance Quarter (1Q 2020): -15.25%

As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 11.61%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2040 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Real Estate Investing Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Real Estate Investing Risk - An investment in the fund may be subject to many of the same risks as a direct investment in real estate. These risks include changes in economic conditions, interest rates, property values, property tax increases, overbuilding and increased competition, environmental contamination, zoning and natural disasters. This is due to the fact that the value of the fund’s investments may be affected by the value of the real estate owned by the companies in which it invests.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | S&P Target Date To 2040 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2040 Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 18.16%
5 Years rr_AverageAnnualReturnYear05 9.73%
10 Years rr_AverageAnnualReturnYear10 7.06%
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [25]
Label rr_AverageAnnualReturnLabel Russell 3000® Index3(reflects no deduction for fees, expenses or taxes) [25]
1 Year rr_AverageAnnualReturnYear01 25.96% [25]
5 Years rr_AverageAnnualReturnYear05 15.16% [25]
10 Years rr_AverageAnnualReturnYear10 11.48% [25]
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [25]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index3(reflects no deduction for fees, expenses or taxes) [25]
1 Year rr_AverageAnnualReturnYear01 5.53% [25]
5 Years rr_AverageAnnualReturnYear05 1.10% [25]
10 Years rr_AverageAnnualReturnYear10 1.81% [25]
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARDVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.86% [26]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.88%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [27]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.85%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 87
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 278
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 485
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,082
Annual Return 2014 rr_AnnualReturn2014 8.03%
Annual Return 2015 rr_AnnualReturn2015 (1.32%)
Annual Return 2016 rr_AnnualReturn2016 6.80%
Annual Return 2017 rr_AnnualReturn2017 16.07%
Annual Return 2018 rr_AnnualReturn2018 (6.53%)
Annual Return 2019 rr_AnnualReturn2019 21.32%
Annual Return 2020 rr_AnnualReturn2020 15.11%
Annual Return 2021 rr_AnnualReturn2021 11.45%
Annual Return 2022 rr_AnnualReturn2022 (16.39%)
Annual Return 2023 rr_AnnualReturn2023 13.64%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 11.61%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.58%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (15.25%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.64%
5 Years rr_AverageAnnualReturnYear05 8.14%
10 Years rr_AverageAnnualReturnYear10 6.21%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 12.82%
5 Years rr_AverageAnnualReturnYear05 6.41%
10 Years rr_AverageAnnualReturnYear10 4.64%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 8.30%
5 Years rr_AverageAnnualReturnYear05 6.12%
10 Years rr_AverageAnnualReturnYear10 4.59%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARDSX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.66% [26]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.68%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [27]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.65%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 67
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 215
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 376
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 844
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.87%
5 Years rr_AverageAnnualReturnYear05 8.36%
10 Years rr_AverageAnnualReturnYear10 6.42%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARDMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [28]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.86% [26]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.13%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [27]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.10%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 681
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 911
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,159
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,868
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 6.84%
5 Years rr_AverageAnnualReturnYear05 6.60%
10 Years rr_AverageAnnualReturnYear10 5.32%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARNOX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.86% [26]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.88%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [27]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.85%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 188
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 589
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,014
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,001
Label rr_AverageAnnualReturnLabel C Class1 Return Before Taxes [29]
1 Year rr_AverageAnnualReturnYear01 12.53% [29]
5 Years rr_AverageAnnualReturnYear05 7.08% [29]
10 Years rr_AverageAnnualReturnYear10 5.32% [29]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [29]
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARDRX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.86% [26]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.38%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [27]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.35%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 138
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 435
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 753
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,654
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.08%
5 Years rr_AverageAnnualReturnYear05 7.60%
10 Years rr_AverageAnnualReturnYear10 5.69%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARDUX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55% [26]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.57%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [27]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.50%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 51
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 176
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 312
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 707
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.01%
5 Years rr_AverageAnnualReturnYear05 8.53%
10 Years rr_AverageAnnualReturnYear10 6.58% [30]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2045 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 13% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 13.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice 2045 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)67.5 %
U.S. Equity46.5 %
International Equity19.0 %
Real Estate2.0 %
Fixed-Income Securities (Bond Funds)32.5 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2045) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The fund assumes a retirement age of 65 and may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. As the target date approaches, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. By the time the fund reaches its target date, the neutral mix will become fixed and match that of One Choice In Retirement Portfolio, which is currently 45% stock funds, 47.3% bond funds and 7.7% short-term funds. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.

Glide path.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice 2045 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2045 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2045 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (2Q 2020): 16.91% Lowest Performance Quarter (1Q 2020): -16.48%

As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 12.45%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2045 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Real Estate Investing Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Real Estate Investing Risk - An investment in the fund may be subject to many of the same risks as a direct investment in real estate. These risks include changes in economic conditions, interest rates, property values, property tax increases, overbuilding and increased competition, environmental contamination, zoning and natural disasters. This is due to the fact that the value of the fund’s investments may be affected by the value of the real estate owned by the companies in which it invests.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | S&P Target Date To 2045 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2045 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 19.57%
5 Years rr_AverageAnnualReturnYear05 10.31%
10 Years rr_AverageAnnualReturnYear10 7.39%
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [31]
Label rr_AverageAnnualReturnLabel Russell 3000® Index3(reflects no deduction for fees, expenses or taxes) [31]
1 Year rr_AverageAnnualReturnYear01 25.96% [31]
5 Years rr_AverageAnnualReturnYear05 15.16% [31]
10 Years rr_AverageAnnualReturnYear10 11.48% [31]
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [31]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index3(reflects no deduction for fees, expenses or taxes) [31]
1 Year rr_AverageAnnualReturnYear01 5.53% [31]
5 Years rr_AverageAnnualReturnYear05 1.10% [31]
10 Years rr_AverageAnnualReturnYear10 1.81% [31]
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AROIX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.88% [32]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.90%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [33]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.88%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 90
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 285
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 497
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,106
Annual Return 2014 rr_AnnualReturn2014 8.40%
Annual Return 2015 rr_AnnualReturn2015 (1.38%)
Annual Return 2016 rr_AnnualReturn2016 7.15%
Annual Return 2017 rr_AnnualReturn2017 17.51%
Annual Return 2018 rr_AnnualReturn2018 (7.16%)
Annual Return 2019 rr_AnnualReturn2019 22.72%
Annual Return 2020 rr_AnnualReturn2020 16.41%
Annual Return 2021 rr_AnnualReturn2021 12.30%
Annual Return 2022 rr_AnnualReturn2022 (17.01%)
Annual Return 2023 rr_AnnualReturn2023 14.31%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 12.45%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 16.91%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (16.48%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.31%
5 Years rr_AverageAnnualReturnYear05 8.76%
10 Years rr_AverageAnnualReturnYear10 6.64%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 13.57%
5 Years rr_AverageAnnualReturnYear05 7.10%
10 Years rr_AverageAnnualReturnYear10 5.06%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 8.74%
5 Years rr_AverageAnnualReturnYear05 6.66%
10 Years rr_AverageAnnualReturnYear10 4.95%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AOOIX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.69% [32]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.71%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [33]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.68%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 70
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 224
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 393
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 880
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.59%
5 Years rr_AverageAnnualReturnYear05 8.99%
10 Years rr_AverageAnnualReturnYear10 6.86%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AROAX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [34]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.88% [32]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.15%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [33]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.13%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 684
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 918
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,170
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,890
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 7.54%
5 Years rr_AverageAnnualReturnYear05 7.21%
10 Years rr_AverageAnnualReturnYear10 5.75%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AROCX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.88% [32]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.90%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [33]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.88%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 191
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 596
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,025
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,023
Label rr_AverageAnnualReturnLabel C Class1 Return Before Taxes [35]
1 Year rr_AverageAnnualReturnYear01 13.29% [35]
5 Years rr_AverageAnnualReturnYear05 7.68% [35]
10 Years rr_AverageAnnualReturnYear10 5.74% [35]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [35]
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARORX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.88% [32]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.40%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [33]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.38%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 141
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 442
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 765
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,677
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.80%
5 Years rr_AverageAnnualReturnYear05 8.22%
10 Years rr_AverageAnnualReturnYear10 6.11%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARDOX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.56% [32]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.58%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [33]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.53%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 54
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 181
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 319
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 722
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.70%
5 Years rr_AverageAnnualReturnYear05 9.14%
10 Years rr_AverageAnnualReturnYear10 7.01% [36]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2050 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 14% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 14.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice 2050 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)73.8 %
U.S. Equity50.9 %
International Equity20.7 %
Real Estate2.2 %
Fixed-Income Securities (Bond Funds)26.2 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2050) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The fund assumes a retirement age of 65 and may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. As the target date approaches, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. By the time the fund reaches its target date, the neutral mix will become fixed and match that of One Choice In Retirement Portfolio, which is currently 45% stock funds, 47.3% bond funds and 7.7% short-term funds. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide path.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice 2050 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2050 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2050 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (2Q 2020): 18.13% Lowest Performance Quarter (1Q 2020): -17.77%

As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 13.24%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2050 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Real Estate Investing Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Real Estate Investing Risk - An investment in the fund may be subject to many of the same risks as a direct investment in real estate. These risks include changes in economic conditions, interest rates, property values, property tax increases, overbuilding and increased competition, environmental contamination, zoning and natural disasters. This is due to the fact that the value of the fund’s investments may be affected by the value of the real estate owned by the companies in which it invests.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | S&P Target Date To 2050 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2050 Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 20.21%
5 Years rr_AverageAnnualReturnYear05 10.67%
10 Years rr_AverageAnnualReturnYear10 7.62%
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [37]
Label rr_AverageAnnualReturnLabel Russell 3000® Index3(reflects no deduction for fees, expenses or taxes) [37]
1 Year rr_AverageAnnualReturnYear01 25.96% [37]
5 Years rr_AverageAnnualReturnYear05 15.16% [37]
10 Years rr_AverageAnnualReturnYear10 11.48% [37]
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [37]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index3(reflects no deduction for fees, expenses or taxes) [37]
1 Year rr_AverageAnnualReturnYear01 5.53% [37]
5 Years rr_AverageAnnualReturnYear05 1.10% [37]
10 Years rr_AverageAnnualReturnYear10 1.81% [37]
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARFVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.90% [38]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.92%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [39]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.90%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 92
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 292
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 508
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,130
Annual Return 2014 rr_AnnualReturn2014 8.60%
Annual Return 2015 rr_AnnualReturn2015 (1.59%)
Annual Return 2016 rr_AnnualReturn2016 7.40%
Annual Return 2017 rr_AnnualReturn2017 18.59%
Annual Return 2018 rr_AnnualReturn2018 (7.72%)
Annual Return 2019 rr_AnnualReturn2019 24.08%
Annual Return 2020 rr_AnnualReturn2020 17.43%
Annual Return 2021 rr_AnnualReturn2021 13.37%
Annual Return 2022 rr_AnnualReturn2022 (17.39%)
Annual Return 2023 rr_AnnualReturn2023 15.14%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 13.24%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.13%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (17.77%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.14%
5 Years rr_AverageAnnualReturnYear05 9.46%
10 Years rr_AverageAnnualReturnYear10 7.03%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 14.49%
5 Years rr_AverageAnnualReturnYear05 7.77%
10 Years rr_AverageAnnualReturnYear10 5.50%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 9.22%
5 Years rr_AverageAnnualReturnYear05 7.22%
10 Years rr_AverageAnnualReturnYear10 5.29%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARFSX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.71% [38]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.73%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.03%) [39]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.70%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 72
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 231
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 404
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 904
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.35%
5 Years rr_AverageAnnualReturnYear05 9.68%
10 Years rr_AverageAnnualReturnYear10 7.25%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARFMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [40]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.90% [38]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.17%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [39]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.15%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 686
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 924
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,181
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,912
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 8.16%
5 Years rr_AverageAnnualReturnYear05 7.90%
10 Years rr_AverageAnnualReturnYear10 6.13%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARFDX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.90% [38]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.92%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [39]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.90%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 193
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 602
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,036
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,045
Label rr_AverageAnnualReturnLabel C Class1 Return Before Taxes [41]
1 Year rr_AverageAnnualReturnYear01 13.93% [41]
5 Years rr_AverageAnnualReturnYear05 8.36% [41]
10 Years rr_AverageAnnualReturnYear10 6.13% [41]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [41]
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARFWX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.90% [38]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.42%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [39]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.40%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 143
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 448
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 775
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,699
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.55%
5 Years rr_AverageAnnualReturnYear05 8.91%
10 Years rr_AverageAnnualReturnYear10 6.51%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARFEX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58% [38]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.60%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [39]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.55%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 56
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 187
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 330
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 746
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.46%
5 Years rr_AverageAnnualReturnYear05 9.83%
10 Years rr_AverageAnnualReturnYear10 7.39% [42]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2055 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 15% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 15.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice 2055 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)80.0 %
U.S. Equity55.1 %
International Equity22.5 %
Real Estate2.4 %
Fixed-Income Securities (Bond Funds)20.0 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2055) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The fund assumes a retirement age of 65 and may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. As the target date approaches, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. By the time the fund reaches its target date, the neutral mix will become fixed and match that of One Choice In Retirement Portfolio, which is currently 45% stock funds, 47.3% bond funds and 7.7% short-term funds. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.


Glide path.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice 2055 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2055 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2055 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (2Q 2020): 18.62% Lowest Performance Quarter (1Q 2020): -18.24%

As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 13.93%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2055 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Real Estate Investing Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Real Estate Investing Risk - An investment in the fund may be subject to many of the same risks as a direct investment in real estate. These risks include changes in economic conditions, interest rates, property values, property tax increases, overbuilding and increased competition, environmental contamination, zoning and natural disasters. This is due to the fact that the value of the fund’s investments may be affected by the value of the real estate owned by the companies in which it invests.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | S&P Target Date To 2055 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2055 Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 20.21%
5 Years rr_AverageAnnualReturnYear05 10.70%
10 Years rr_AverageAnnualReturnYear10 7.67%
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [43]
Label rr_AverageAnnualReturnLabel Russell 3000® Index3(reflects no deduction for fees, expenses or taxes) [43]
1 Year rr_AverageAnnualReturnYear01 25.96% [43]
5 Years rr_AverageAnnualReturnYear05 15.16% [43]
10 Years rr_AverageAnnualReturnYear10 11.48% [43]
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [43]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index3(reflects no deduction for fees, expenses or taxes) [43]
1 Year rr_AverageAnnualReturnYear01 5.53% [43]
5 Years rr_AverageAnnualReturnYear05 1.10% [43]
10 Years rr_AverageAnnualReturnYear10 1.81% [43]
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AREVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92% [44]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.93%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [45]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.89%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 293
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 511
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,139
Annual Return 2014 rr_AnnualReturn2014 8.80%
Annual Return 2015 rr_AnnualReturn2015 (1.64%)
Annual Return 2016 rr_AnnualReturn2016 7.60%
Annual Return 2017 rr_AnnualReturn2017 19.04%
Annual Return 2018 rr_AnnualReturn2018 (8.03%)
Annual Return 2019 rr_AnnualReturn2019 24.54%
Annual Return 2020 rr_AnnualReturn2020 17.91%
Annual Return 2021 rr_AnnualReturn2021 13.87%
Annual Return 2022 rr_AnnualReturn2022 (17.61%)
Annual Return 2023 rr_AnnualReturn2023 15.76%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 13.93%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.62%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (18.24%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.76%
5 Years rr_AverageAnnualReturnYear05 9.78%
10 Years rr_AverageAnnualReturnYear10 7.23%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 15.27%
5 Years rr_AverageAnnualReturnYear05 8.27%
10 Years rr_AverageAnnualReturnYear10 5.91%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 9.56%
5 Years rr_AverageAnnualReturnYear05 7.52%
10 Years rr_AverageAnnualReturnYear10 5.52%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARENX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.72% [44]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.73%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [45]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.69%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 71
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 230
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 403
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 903
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.91%
5 Years rr_AverageAnnualReturnYear05 9.99%
10 Years rr_AverageAnnualReturnYear10 7.45%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AREMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [46]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92% [44]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.18%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [45]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.14%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 685
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 925
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,184
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,921
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 8.77%
5 Years rr_AverageAnnualReturnYear05 8.21%
10 Years rr_AverageAnnualReturnYear10 6.33%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AREFX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92% [44]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.93%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [45]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.89%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 192
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 603
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,039
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,054
Label rr_AverageAnnualReturnLabel C Class1 Return Before Taxes [47]
1 Year rr_AverageAnnualReturnYear01 14.57% [47]
5 Years rr_AverageAnnualReturnYear05 8.68% [47]
10 Years rr_AverageAnnualReturnYear10 6.32% [47]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011 [47]
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AREOX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92% [44]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.43%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [45]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.39%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 142
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 449
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 779
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,709
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.17%
5 Years rr_AverageAnnualReturnYear05 9.23%
10 Years rr_AverageAnnualReturnYear10 6.70%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AREUX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.59% [44]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.60%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [45]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.54%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 55
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 186
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 329
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 745
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.10%
5 Years rr_AverageAnnualReturnYear05 10.15%
10 Years rr_AverageAnnualReturnYear10 7.60% [48]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2060 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 15% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 15.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice 2060 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)82.5 %
U.S. Equity56.8 %
International Equity23.2 %
Real Estate2.5 %
Fixed-Income Securities (Bond Funds)17.5 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2060) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The fund assumes a retirement age of 65 and may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. As the target date approaches, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. By the time the fund reaches its target date, the neutral mix will become fixed and match that of One Choice In Retirement Portfolio, which is currently 45% stock funds, 47.3% bond funds and 7.7% short-term funds. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.

Glide path.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice 2060 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2060 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2060 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (2Q 2020): 18.98% Lowest Performance Quarter (1Q 2020): -18.68%

As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 14.26%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2060 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Real Estate Investing Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Real Estate Investing Risk - An investment in the fund may be subject to many of the same risks as a direct investment in real estate. These risks include changes in economic conditions, interest rates, property values, property tax increases, overbuilding and increased competition, environmental contamination, zoning and natural disasters. This is due to the fact that the value of the fund’s investments may be affected by the value of the real estate owned by the companies in which it invests.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | S&P Target Date To 2060 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2060 Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 20.44%
5 Years rr_AverageAnnualReturnYear05 10.96%
Since Inception rr_AverageAnnualReturnSinceInception 9.63%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [49]
Label rr_AverageAnnualReturnLabel Russell 3000® Index2(reflects no deduction for fees, expenses or taxes) [49]
1 Year rr_AverageAnnualReturnYear01 25.96% [49]
5 Years rr_AverageAnnualReturnYear05 15.16% [49]
Since Inception rr_AverageAnnualReturnSinceInception 13.21% [49]
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015 [49]
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [49]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index2(reflects no deduction for fees, expenses or taxes) [49]
1 Year rr_AverageAnnualReturnYear01 5.53% [49]
5 Years rr_AverageAnnualReturnYear05 1.10% [49]
Since Inception rr_AverageAnnualReturnSinceInception 1.34% [49]
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015 [49]
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARGVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.93% [50]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.94%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [51]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.89%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 295
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 516
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,150
Annual Return 2016 rr_AnnualReturn2016 7.71%
Annual Return 2017 rr_AnnualReturn2017 19.31%
Annual Return 2018 rr_AnnualReturn2018 (8.13%)
Annual Return 2019 rr_AnnualReturn2019 24.88%
Annual Return 2020 rr_AnnualReturn2020 18.10%
Annual Return 2021 rr_AnnualReturn2021 14.38%
Annual Return 2022 rr_AnnualReturn2022 (17.80%)
Annual Return 2023 rr_AnnualReturn2023 16.05%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 14.26%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.98%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (18.68%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.05%
5 Years rr_AverageAnnualReturnYear05 9.98%
Since Inception rr_AverageAnnualReturnSinceInception 8.58%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 15.55%
5 Years rr_AverageAnnualReturnYear05 8.64%
Since Inception rr_AverageAnnualReturnSinceInception 7.46%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 9.76%
5 Years rr_AverageAnnualReturnYear05 7.69%
Since Inception rr_AverageAnnualReturnSinceInception 6.68%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARGNX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.73% [50]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.74%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [51]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.69%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 71
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 232
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 407
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 914
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.27%
5 Years rr_AverageAnnualReturnYear05 10.21%
Since Inception rr_AverageAnnualReturnSinceInception 8.81%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARGMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [52]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.93% [50]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.19%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [51]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.14%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 685
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 927
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,188
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,931
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.11%
5 Years rr_AverageAnnualReturnYear05 8.43%
Since Inception rr_AverageAnnualReturnSinceInception 7.54%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARGHX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.93% [50]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.94%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [51]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.89%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 192
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 605
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,043
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,064
Label rr_AverageAnnualReturnLabel C Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.93%
5 Years rr_AverageAnnualReturnYear05 8.91%
Since Inception rr_AverageAnnualReturnSinceInception 7.54%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARGRX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.93% [50]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.44%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [51]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.39%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 142
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 451
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 783
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,719
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.47%
5 Years rr_AverageAnnualReturnYear05 9.45%
Since Inception rr_AverageAnnualReturnSinceInception 8.05%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARGDX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60% [50]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.61%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [51]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.54%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 55
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 189
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 334
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 756
Label rr_AverageAnnualReturnLabel R6 Class1 Return Before Taxes [53]
1 Year rr_AverageAnnualReturnYear01 16.48% [53]
5 Years rr_AverageAnnualReturnYear05 10.39% [53]
Since Inception rr_AverageAnnualReturnSinceInception 8.95% [53]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [53]
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2065 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 61 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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 8% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 8.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent The management fee has been restated to reflect current fees.
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice 2065 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)85.0 %
U.S. Equity58.6 %
International Equity23.9 %
Real Estate2.5 %
Fixed-Income Securities (Bond Funds)15.0 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2065) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The fund assumes a retirement age of 65 and may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. As the target date approaches, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. By the time the fund reaches its target date, the neutral mix will become fixed and match that of One Choice In Retirement Portfolio, which is currently 45% stock funds, 47.3% bond funds and 7.7% short-term funds. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.

Glide path.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice 2065 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century mutual funds (the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2065+ Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2065+ Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 10.17% Lowest Performance Quarter (2Q 2022): -14.01%

As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 14.60%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2065+ Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Real Estate Investing Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Real Estate Investing Risk - An investment in the fund may be subject to many of the same risks as a direct investment in real estate. These risks include changes in economic conditions, interest rates, property values, property tax increases, overbuilding and increased competition, environmental contamination, zoning and natural disasters. This is due to the fact that the value of the fund’s investments may be affected by the value of the real estate owned by the companies in which it invests.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | S&P Target Date to 2065+ Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date to 2065+ Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 20.84%
Since Inception rr_AverageAnnualReturnSinceInception 11.04%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [54]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [54]
1 Year rr_AverageAnnualReturnYear01 25.96% [54]
Since Inception rr_AverageAnnualReturnSinceInception 13.76% [54]
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020 [54]
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [54]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [54]
1 Year rr_AverageAnnualReturnYear01 5.53% [54]
Since Inception rr_AverageAnnualReturnSinceInception (2.88%) [54]
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020 [54]
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARHVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94% [55]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.95%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [56]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.89%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 297
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 520
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,161
Annual Return 2021 rr_AnnualReturn2021 14.55%
Annual Return 2022 rr_AnnualReturn2022 (17.74%)
Annual Return 2023 rr_AnnualReturn2023 16.23%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 14.60%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.17%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.01%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.23%
Since Inception rr_AverageAnnualReturnSinceInception 7.74%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 15.72%
Since Inception rr_AverageAnnualReturnSinceInception 6.70%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 9.88%
Since Inception rr_AverageAnnualReturnSinceInception 5.77%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARHUX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.74% [55]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.75%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [56]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.69%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 71
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 234
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 412
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 925
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.47%
Since Inception rr_AverageAnnualReturnSinceInception 7.92%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARHMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [57]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94% [55]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.20%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [56]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.14%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 685
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 929
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,192
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,941
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.29%
Since Inception rr_AverageAnnualReturnSinceInception 5.51%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | C CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARHEX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94% [55]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.95%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [56]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.89%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 192
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 607
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,047
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,073
Label rr_AverageAnnualReturnLabel C Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.08%
Since Inception rr_AverageAnnualReturnSinceInception 6.66%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARHFX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94% [55]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.45%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [56]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.39%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 142
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 453
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 787
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,729
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.65%
Since Inception rr_AverageAnnualReturnSinceInception 7.20%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020
American Century Asset Allocation Portfolio | ONE CHOICE 2065 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol ARHSX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60% [55]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.61%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [56]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.54%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2025
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 55
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 189
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 334
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 756
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.63%
Since Inception rr_AverageAnnualReturnSinceInception 8.11%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 23, 2020
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2015 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice Blend+ 2015 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)40.0 %
U.S. Equity29.5 %
International Equity9.5 %
Real Estate1.0 %
Fixed-Income Securities (Bond Funds)54.0 %
Short-Term Investments (Short-Term Funds)6.0 %
The target date in the fund name (2015) refers to the approximate year an investor retired. Any new investments in the fund are being made after the target date. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who retired at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. The fund’s neutral mix is expected to remain fixed at 40% stock funds, 54% bond funds and 6% short-term funds.
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2015 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2015 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2015 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 7.83% Lowest Performance Quarter (2Q 2022): -9.00%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 8.75%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2015 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | High-Yield Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock High-Yield Securities Risk – Some of the underlying funds may invest in high-yield securities, which are considered to have speculative characteristics and are more likely to be negatively affected by changes in economic conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | S&P Target Date 2015 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date 2015 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 11.38%
Since Inception rr_AverageAnnualReturnSinceInception 1.67%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [58]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [58]
1 Year rr_AverageAnnualReturnYear01 25.96% [58]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [58]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [58]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [58]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [58]
1 Year rr_AverageAnnualReturnYear01 5.53% [58]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [58]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [58]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAAFX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.62%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [59]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.60%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 61
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 193
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 335
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 751
Annual Return 2022 rr_AnnualReturn2022 (12.86%)
Annual Return 2023 rr_AnnualReturn2023 10.65%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 8.75%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.83%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (9.00%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.65%
Since Inception rr_AverageAnnualReturnSinceInception 0.81%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 9.62%
Since Inception rr_AverageAnnualReturnSinceInception (0.16%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 6.42%
Since Inception rr_AverageAnnualReturnSinceInception 0.27%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAAHX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.42%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [59]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.40%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 41
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 129
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 225
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 506
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.76%
Since Inception rr_AverageAnnualReturnSinceInception 0.98%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAAJX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [60]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.87%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [59]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.85%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 657
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 831
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,020
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,564
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 4.03%
Since Inception rr_AverageAnnualReturnSinceInception (1.53%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAAKX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.12%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [59]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 350
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 607
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,340
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.99%
Since Inception rr_AverageAnnualReturnSinceInception 0.27%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2015 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAALX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.27%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [59]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.25%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 26
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 81
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 141
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 319
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.04%
Since Inception rr_AverageAnnualReturnSinceInception 1.17%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2020 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 48% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 48.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice Blend+ 2020 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)40.0 %
U.S. Equity29.5 %
International Equity9.5 %
Real Estate1.0 %
Fixed-Income Securities (Bond Funds)54.0 %
Short-Term Investments (Short-Term Funds)6.0 %
The target date in the fund name (2020) refers to the approximate year an investor retired. Any new investments in the fund are being made after the target date. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who retired at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide Path 12.01.2024.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2020 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2020 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2020 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 7.86% Lowest Performance Quarter (2Q 2022): -9.27%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 8.78%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2020 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk - ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | High-Yield Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock High-Yield Securities Risk – Some of the underlying funds may invest in high-yield securities, which are considered to have speculative characteristics and are more likely to be negatively affected by changes in economic conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | S&P Target Date To 2020 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2020 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 10.92%
Since Inception rr_AverageAnnualReturnSinceInception 1.43%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [61]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [61]
1 Year rr_AverageAnnualReturnYear01 25.96% [61]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [61]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [61]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [61]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [61]
1 Year rr_AverageAnnualReturnYear01 5.53% [61]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [61]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [61]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAAMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.62%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [62]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.60%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 61
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 193
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 335
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 751
Annual Return 2022 rr_AnnualReturn2022 (13.18%)
Annual Return 2023 rr_AnnualReturn2023 10.80%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 8.78%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.86%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (9.27%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.80%
Since Inception rr_AverageAnnualReturnSinceInception 0.99%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 9.96%
Since Inception rr_AverageAnnualReturnSinceInception 0.07%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 6.49%
Since Inception rr_AverageAnnualReturnSinceInception 0.43%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAAOX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.42%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [62]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.40%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 41
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 129
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 225
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 506
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABEX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [63]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.87%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [62]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.85%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 657
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 831
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,020
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,564
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 4.06%
Since Inception rr_AverageAnnualReturnSinceInception (1.40%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABGX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.12%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [62]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 350
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 607
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,340
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.13%
Since Inception rr_AverageAnnualReturnSinceInception 0.45%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABHX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.27%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.02%) [62]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.25%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 26
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 81
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 141
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 319
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.18%
Since Inception rr_AverageAnnualReturnSinceInception 1.35%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2020 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.90%
Since Inception rr_AverageAnnualReturnSinceInception 1.16%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2025 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 51% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 51.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice Blend+ 2025 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)46.2 %
U.S. Equity33.5 %
International Equity11.5 %
Real Estate1.2 %
Fixed-Income Securities (Bond Funds)50.2 %
Short-Term Investments (Short-Term Funds)3.6 %
The target date in the fund name (2025) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide Path 12.01.2024.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2025 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2025 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2025 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 8.28% Lowest Performance Quarter (2Q 2022): -10.06%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 9.59%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2025 Index as a result of recent regulatory changes requiring that represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock 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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | High-Yield Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock High-Yield Securities Risk – Some of the underlying funds may invest in high-yield securities, which are considered to have speculative characteristics and are more likely to be negatively affected by changes in economic conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | S&P Target Date To 2025 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2025 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 12.44%
Since Inception rr_AverageAnnualReturnSinceInception 2.10%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [64]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [64]
1 Year rr_AverageAnnualReturnYear01 25.96% [64]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [64]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [64]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [64]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [64]
1 Year rr_AverageAnnualReturnYear01 5.53% [64]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [64]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [64]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABJX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.61%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [65]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.60%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 61
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 193
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 335
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 751
Annual Return 2022 rr_AnnualReturn2022 (13.72%)
Annual Return 2023 rr_AnnualReturn2023 11.65%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 9.59%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 8.28%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (10.06%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.65%
Since Inception rr_AverageAnnualReturnSinceInception 0.97%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 10.77%
Since Inception rr_AverageAnnualReturnSinceInception (0.03%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 7.02%
Since Inception rr_AverageAnnualReturnSinceInception 0.40%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABKX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.41%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [65]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.40%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 41
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 129
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 225
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 506
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.87%
Since Inception rr_AverageAnnualReturnSinceInception 1.17%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABQX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [66]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.86%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [65]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.85%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 657
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 831
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,020
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,564
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 4.97%
Since Inception rr_AverageAnnualReturnSinceInception (1.38%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABRX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.11%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [65]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 350
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 607
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,340
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.26%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [65]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.25%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 26
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 81
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 141
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 319
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.09%
Since Inception rr_AverageAnnualReturnSinceInception 0.47%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2025 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.04%
Since Inception rr_AverageAnnualReturnSinceInception 1.33%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2030 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 28% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 28.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. 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
One Choice Blend+ 2030 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)55.0 %
U.S. Equity39.1 %
International Equity14.4 %
Real Estate1.5 %
Fixed-Income Securities (Bond Funds)43.5 %
Short-Term Investments (Short-Term Funds)1.5 %
The target date in the fund name (2030) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.

Glide Path 12.01.2024.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2030 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2030 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2030 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 8.69% Lowest Performance Quarter (2Q 2022): -11.14%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 10.49%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2030 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price. Investing in securities of companies located in emerging market countries is generally riskier than investing in securities of companies located in developed foreign countries.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | High-Yield Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock High-Yield Securities Risk – Some of the underlying funds may invest in high-yield securities, which are considered to have speculative characteristics and are more likely to be negatively affected by changes in economic conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | S&P Target Date To 2030 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2030 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 14.43%
Since Inception rr_AverageAnnualReturnSinceInception 2.74%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [67]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [67]
1 Year rr_AverageAnnualReturnYear01 25.96% [67]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [67]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [67]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [67]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [67]
1 Year rr_AverageAnnualReturnYear01 5.53% [67]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [67]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [67]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABWX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.61%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [68]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.60%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 61
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 193
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 335
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 751
Annual Return 2022 rr_AnnualReturn2022 (14.47%)
Annual Return 2023 rr_AnnualReturn2023 12.72%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 10.49%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 8.69%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (11.14%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.72%
Since Inception rr_AverageAnnualReturnSinceInception 1.12%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 11.93%
Since Inception rr_AverageAnnualReturnSinceInception 0.17%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 7.67%
Since Inception rr_AverageAnnualReturnSinceInception 0.55%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEWX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.41%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [68]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.40%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 41
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 129
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 225
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 506
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.06%
Since Inception rr_AverageAnnualReturnSinceInception 1.36%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AABZX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [69]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.86%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [68]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.85%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 657
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 831
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,020
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,564
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 6.09%
Since Inception rr_AverageAnnualReturnSinceInception (1.20%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACHX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.11%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [68]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 350
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 607
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,340
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.28%
Since Inception rr_AverageAnnualReturnSinceInception 0.65%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2030 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACJX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.26%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [68]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.25%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 26
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 81
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 141
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 319
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.23%
Since Inception rr_AverageAnnualReturnSinceInception 1.51%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2035 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 22% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 22.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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
One Choice Blend+ 2035 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)63.7 %
U.S. Equity44.5 %
International Equity17.4 %
Real Estate1.8 %
Fixed-Income Securities (Bond Funds)35.7 %
Short-Term Investments (Short-Term Funds)0.6 %
The target date in the fund name (2035) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide Path 12.01.2024.jpg
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2035 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2035
Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2035 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 9.13% Lowest Performance Quarter (2Q 2022): -12.17%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 11.76%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2035 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | S&P Target Date To 2035 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2035 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 16.48%
Since Inception rr_AverageAnnualReturnSinceInception 3.43%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [70]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [70]
1 Year rr_AverageAnnualReturnYear01 25.96% [70]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [70]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [70]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [70]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [70]
1 Year rr_AverageAnnualReturnYear01 5.53% [70]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [70]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [70]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACKX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.60%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [71]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 189
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 330
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 738
Annual Return 2022 rr_AnnualReturn2022 (15.52%)
Annual Return 2023 rr_AnnualReturn2023 13.85%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 11.76%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.13%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.17%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.85%
Since Inception rr_AverageAnnualReturnSinceInception 1.17%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 13.05%
Since Inception rr_AverageAnnualReturnSinceInception 0.21%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 8.37%
Since Inception rr_AverageAnnualReturnSinceInception 0.61%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACLX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.40%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [71]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 40
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 126
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 219
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 493
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.08%
Since Inception rr_AverageAnnualReturnSinceInception 1.37%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [72]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.85%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [71]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.84%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 656
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 828
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,015
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,553
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 7.04%
Since Inception rr_AverageAnnualReturnSinceInception (1.19%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACPX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.10%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [71]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 602
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.29%
Since Inception rr_AverageAnnualReturnSinceInception 0.66%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2035 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACQX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.25%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.01%) [71]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 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
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.25%
Since Inception rr_AverageAnnualReturnSinceInception 1.52%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2040 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 23% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 23.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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
One Choice Blend+ 2040 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)72.5 %
U.S. Equity49.6 %
International Equity20.7 %
Real Estate2.2 %
Fixed-Income Securities (Bond Funds)27.5 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2040) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide Path 12.01.2024.jpg

The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2040 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2040 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2040 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 9.49% Lowest Performance Quarter (2Q 2022): -13.04%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 13.01%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2040 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | S&P Target Date To 2040 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2040 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 18.16%
Since Inception rr_AverageAnnualReturnSinceInception 3.97%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [73]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [73]
1 Year rr_AverageAnnualReturnYear01 25.96% [73]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [73]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [73]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [73]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [73]
1 Year rr_AverageAnnualReturnYear01 5.53% [73]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [73]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [73]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACSX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 189
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 330
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 738
Annual Return 2022 rr_AnnualReturn2022 (16.18%)
Annual Return 2023 rr_AnnualReturn2023 14.75%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 13.01%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.49%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.04%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.75%
Since Inception rr_AverageAnnualReturnSinceInception 1.39%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 14.03%
Since Inception rr_AverageAnnualReturnSinceInception 0.49%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 8.91%
Since Inception rr_AverageAnnualReturnSinceInception 0.81%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACUX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 40
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 126
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 219
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 493
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.11%
Since Inception rr_AverageAnnualReturnSinceInception 1.60%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [74]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.84%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 656
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 828
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,015
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,553
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 7.88%
Since Inception rr_AverageAnnualReturnSinceInception (0.97%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACWX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 602
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.18%
Since Inception rr_AverageAnnualReturnSinceInception 0.88%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2040 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AACZX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 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
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.15%
Since Inception rr_AverageAnnualReturnSinceInception 1.75%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2045 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 43% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 43.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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
One Choice Blend+ 2045 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)80.0 %
U.S. Equity54.8 %
International Equity22.8 %
Real Estate2.4 %
Fixed-Income Securities (Bond Funds)20.0 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2045) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide Path 12.01.2024.jpg

The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2045 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2045 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2045 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 9.69% Lowest Performance Quarter (2Q 2022): -13.76%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 14.26%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2045 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | S&P Target Date To 2045 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2045 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 19.57%
Since Inception rr_AverageAnnualReturnSinceInception 4.48%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [75]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [75]
1 Year rr_AverageAnnualReturnYear01 25.96% [75]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [75]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [75]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [75]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [75]
1 Year rr_AverageAnnualReturnYear01 5.53% [75]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [75]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [75]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADHX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 189
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 330
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 738
Annual Return 2022 rr_AnnualReturn2022 (16.54%)
Annual Return 2023 rr_AnnualReturn2023 15.59%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 14.26%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.69%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.76%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.59%
Since Inception rr_AverageAnnualReturnSinceInception 1.68%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 14.88%
Since Inception rr_AverageAnnualReturnSinceInception 0.81%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 9.48%
Since Inception rr_AverageAnnualReturnSinceInception 1.06%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADJX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 40
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 126
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 219
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 493
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.71%
Since Inception rr_AverageAnnualReturnSinceInception 1.85%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADKX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [76]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.84%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 656
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 828
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,015
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,553
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 8.57%
Since Inception rr_AverageAnnualReturnSinceInception (0.72%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADLX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 602
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.02%
Since Inception rr_AverageAnnualReturnSinceInception 1.18%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2045 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 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
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.88%
Since Inception rr_AverageAnnualReturnSinceInception 2.00%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2050 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 18% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 18.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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
One Choice Blend+ 2050 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)87.5 %
U.S. Equity59.9 %
International Equity25.0 %
Real Estate2.6 %
Fixed-Income Securities (Bond Funds)12.5 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2050) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide Path 12.01.2024.jpg

The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2050 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2050 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2050 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 9.95% Lowest Performance Quarter (2Q 2022): -14.14%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 15.09%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2050 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | S&P Target Date To 2050 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2050 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 20.21%
Since Inception rr_AverageAnnualReturnSinceInception 4.69%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [77]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [77]
1 Year rr_AverageAnnualReturnYear01 25.96% [77]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [77]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [77]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [77]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [77]
1 Year rr_AverageAnnualReturnYear01 5.53% [77]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [77]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [77]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADNX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 189
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 330
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 738
Annual Return 2022 rr_AnnualReturn2022 (16.74%)
Annual Return 2023 rr_AnnualReturn2023 16.24%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 15.09%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.95%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.14%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.24%
Since Inception rr_AverageAnnualReturnSinceInception 1.96%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 15.54%
Since Inception rr_AverageAnnualReturnSinceInception 1.09%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 9.91%
Since Inception rr_AverageAnnualReturnSinceInception 1.30%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADOX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 40
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 126
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 219
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 493
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.35%
Since Inception rr_AverageAnnualReturnSinceInception 2.13%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADPX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [78]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.84%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 656
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 828
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,015
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,553
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.28%
Since Inception rr_AverageAnnualReturnSinceInception (0.41%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADQX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 602
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.55%
Since Inception rr_AverageAnnualReturnSinceInception 1.42%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2050 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADUX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 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
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.52%
Since Inception rr_AverageAnnualReturnSinceInception 2.29%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2055 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 18% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 18.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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
One Choice Blend+ 2055 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)95.0 %
U.S. Equity65.1 %
International Equity27.1 %
Real Estate2.8 %
Fixed-Income Securities (Bond Funds)5.0 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2055) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide Path 12.01.2024.jpg

The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2055 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2055 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2055 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 10.10% Lowest Performance Quarter (2Q 2022): -14.51%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 15.61%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2055 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | S&P Target Date To 2055 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2055 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 20.21%
Since Inception rr_AverageAnnualReturnSinceInception 4.75%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [79]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [79]
1 Year rr_AverageAnnualReturnYear01 25.96% [79]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [79]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [79]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [79]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [79]
1 Year rr_AverageAnnualReturnYear01 5.53% [79]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [79]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [79]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 189
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 330
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 738
Annual Return 2022 rr_AnnualReturn2022 (16.89%)
Annual Return 2023 rr_AnnualReturn2023 16.67%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 15.61%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.10%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.51%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.67%
Since Inception rr_AverageAnnualReturnSinceInception 2.12%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 16.12%
Since Inception rr_AverageAnnualReturnSinceInception 1.27%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 10.10%
Since Inception rr_AverageAnnualReturnSinceInception 1.42%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADWX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 40
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 126
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 219
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 493
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.91%
Since Inception rr_AverageAnnualReturnSinceInception 2.33%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AADZX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [80]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.84%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 656
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 828
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,015
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,553
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.69%
Since Inception rr_AverageAnnualReturnSinceInception (0.26%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEDX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 602
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.98%
Since Inception rr_AverageAnnualReturnSinceInception 1.57%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2055 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEEX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 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
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.94%
Since Inception rr_AverageAnnualReturnSinceInception 2.48%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2060 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 22% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 22.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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
One Choice Blend+ 2060 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)95.0 %
U.S. Equity65.1 %
International Equity27.1 %
Real Estate2.8 %
Fixed-Income Securities (Bond Funds)5.0 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2060) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide Path 12.01.2024.jpg

The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2060 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2060 Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2060 Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 10.12% Lowest Performance Quarter (2Q 2022): -14.67%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 16.13%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2060 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | S&P Target Date To 2060 Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2060 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 20.44%
Since Inception rr_AverageAnnualReturnSinceInception 4.79%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [81]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [81]
1 Year rr_AverageAnnualReturnYear01 25.96% [81]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [81]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [81]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [81]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [81]
1 Year rr_AverageAnnualReturnYear01 5.53% [81]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [81]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [81]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEFX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 189
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 330
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 738
Annual Return 2022 rr_AnnualReturn2022 (16.93%)
Annual Return 2023 rr_AnnualReturn2023 16.89%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 16.13%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.12%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.67%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.89%
Since Inception rr_AverageAnnualReturnSinceInception 2.21%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 16.25%
Since Inception rr_AverageAnnualReturnSinceInception 1.41%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 10.32%
Since Inception rr_AverageAnnualReturnSinceInception 1.52%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEGX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 40
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 126
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 219
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 493
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.14%
Since Inception rr_AverageAnnualReturnSinceInception 2.38%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEHX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [82]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.84%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 656
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 828
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,015
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,553
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.92%
Since Inception rr_AverageAnnualReturnSinceInception (0.21%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEIX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 602
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.20%
Since Inception rr_AverageAnnualReturnSinceInception 1.66%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2060 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEJX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 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
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.44%
Since Inception rr_AverageAnnualReturnSinceInception 2.57%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Blend+ 2065 Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in 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 66 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
Because the fund buys and sells shares of other American Century mutual funds directly from the issuers, the fund is not expected to incur transaction costs directly other than transaction costs associated with purchasing exchange-traded funds. However, as a shareholder in the underlying mutual funds, the fund indirectly pays transaction costs, such as commissions, when the underlying mutual funds buy and sell securities (or “turn over” their portfolios). 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 17% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 17.00%
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 $50,000 in American Century Investments funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
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
One Choice Blend+ 2065 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles. The underlying stock funds draw on growth, value and quantitative investment techniques and diversify investments among small, medium and large U.S. and foreign companies. The underlying bond funds invest in fixed-income securities that vary by issuer type (corporate and government), credit quality (investment-grade and high-yield or “junk bonds”) and geographic exposure (domestic and international). Short-term investments include underlying funds that invest in fixed-income or debt instruments and have a shorter-term weighted average duration, typically three years or less. The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes as of the date of this prospectus.
Equity Securities (Stock Funds)95.0 %
U.S. Equity65.1 %
International Equity27.1 %
Real Estate2.8 %
Fixed-Income Securities (Bond Funds)5.0 %
Short-Term Investments (Short-Term Funds)0.0 %
The target date in the fund name (2065) refers to the approximate year an investor plans to retire and likely would stop making new investments in the fund. The target date does not necessarily represent the specific year you expect to need your assets. It is intended only as a general guide and assumes a retirement age of 65. The fund may not be appropriate for an investor who plans to retire at or near the target date, but at an age well before or after 65. The fund is designed for investors who plan to withdraw the value of their account gradually after retirement. Over time, the fund’s neutral mix will become more conservative by decreasing the allocation to stocks and increasing the allocation to bonds and short-term investments. The fund will reach its most conservative allocation approximately five years after the target date, at which point its neutral mix is expected to become fixed at 40% stock funds, 54% bond funds and 6% short-term funds. The following chart shows how the neutral mix is expected to change over time according to a predetermined glide path.
Glide Path 12.01.2024.jpg

The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Blend+ 2065 Portfolio is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other mutual funds and exchange-traded funds (ETFs) advised by American Century (collectively, the underlying funds) that represent a variety of asset classes and investment styles.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures of market performance. The table also shows returns for the S&P Target Date to 2065+ Index, which the advisor considers to be more representative of the fund’s investment strategy. 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 broad measures of market performance.
Performance Additional Market Index [Text] rr_PerformanceAdditionalMarketIndex The table also shows returns for the S&P Target Date to 2065+ Index, which the advisor considers to be more representative of the fund’s investment strategy.
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 (4Q 2023): 10.11% Lowest Performance Quarter (2Q 2022): -14.70%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 16.14%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the S&P Target Date to 2065+ Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock •Allocation Risk – The fund’s performance and risks depend in part on the managers’ skill in determining the fund’s neutral mix, selecting and weighting the underlying funds, and implementing any deviations from the neutral mix. The managers’ evaluations and assumptions regarding asset classes or underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | ETF Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock ETF Risk – ETF shares are based on market price rather than net asset value (NAV), as a result, shares may trade at a price greater than NAV (a premium) or less than NAV (a discount). The fund may also incur brokerage commissions, as well as the cost of the bid/ask spread, when purchasing or selling ETF shares.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by any erosion in the ability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Emerging Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Emerging Market Risk - Investing in securities of companies located in emerging market countries generally is also riskier than investing in securities of companies located in foreign developed countries. Emerging market countries may have unstable governments and/or economies that are subject to sudden change. These changes may be magnified by the countries’ emergent financial markets, resulting in significant volatility to investments in these countries.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | S&P Target Date to 2065+ Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel S&P Target Date To 2065+ Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 20.84%
Since Inception rr_AverageAnnualReturnSinceInception 5.08%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [83]
Label rr_AverageAnnualReturnLabel Russell 3000® Index1(reflects no deduction for fees, expenses or taxes) [83]
1 Year rr_AverageAnnualReturnYear01 25.96% [83]
Since Inception rr_AverageAnnualReturnSinceInception 7.33% [83]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [83]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes) [83]
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index1(reflects no deduction for fees, expenses or taxes) [83]
1 Year rr_AverageAnnualReturnYear01 5.53% [83]
Since Inception rr_AverageAnnualReturnSinceInception (2.55%) [83]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021 [83]
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEKX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.59%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 60
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 189
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 330
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 738
Annual Return 2022 rr_AnnualReturn2022 (16.90%)
Annual Return 2023 rr_AnnualReturn2023 16.83%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 16.14%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 10.11%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.70%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.83%
Since Inception rr_AverageAnnualReturnSinceInception 2.40%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 16.30%
Since Inception rr_AverageAnnualReturnSinceInception 1.50%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 10.22%
Since Inception rr_AverageAnnualReturnSinceInception 1.65%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | I CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAELX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.38%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 40
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 126
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 219
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 493
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.20%
Since Inception rr_AverageAnnualReturnSinceInception 2.60%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | A CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEOX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none [84]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.84%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock 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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 656
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 828
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,015
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,553
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.86%
Since Inception rr_AverageAnnualReturnSinceInception (0.02%)
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEUX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 602
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.39%
Since Inception rr_AverageAnnualReturnSinceInception 1.89%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE BLEND+ 2065 PORTFOLIO | R6 CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AAEVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice 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 none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 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
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.38%
Since Inception rr_AverageAnnualReturnSinceInception 2.76%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 10, 2021
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Portfolio: Very Conservative
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 15% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 15.00%
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
One Choice Portfolio: Very Conservative is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy emphasizes investments in fixed-income securities and short-term investments, but maintains a portion of the fund’s assets in equity securities.
The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes over the long term as of the date of this prospectus.
Equity Securities (Stock Funds)25.0 %
U.S. Equity23.0 %
International Equity0.0 %
Real Estate2.0 %
Fixed-Income Securities (Bond Funds)62.0 %
Short-Term Investments (Short-Term Funds)13.0 %
The managers regularly review the fund and may make changes to the fund’s asset class allocations that deviate from the neutral mix to emphasize investments that they believe will provide the most favorable outlook for achieving the fund’s objective. The fund also may deviate from the neutral mix due to differences in asset class performance or prevailing market conditions. The following table shows the operating ranges within which the fund’s asset class allocations generally will vary over short-term periods.
 Equity Securities
(Stock Funds)		Fixed-Income Securities
(Bond Funds)		Short-Term Investments
(Short-Term Funds)
Operating Ranges20-30%52-72%3-25%
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Portfolio: Very Conservative is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy emphasizes investments in fixed-income securities and short-term investments, but maintains a portion of the fund’s assets in equity securities.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures 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 broad measures 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 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 (2Q 2020): 7.96% Lowest Performance Quarter (2Q 2022): -7.02%
As of September 30, 2024 the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 7.33%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
•Allocation Risk – The fund’s ability to achieve its investment objective depends in part on the managers’ skill in determining the funds’ asset class allocations and in selecting and weighting the underlying funds. The managers’ evaluations and assumptions regarding asset classes and underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. Shareholders of the fund will also indirectly bear their pro rata share of the expenses of such underlying funds. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by the inability or perceived inability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | MSCI ACWI IMI (reflects no deductions for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deductions for fees, expenses or taxes) [85]
Label rr_AverageAnnualReturnLabel MSCI ACWI IMI2(reflects no deductions for fees, expenses or taxes) [85]
1 Year rr_AverageAnnualReturnYear01 21.58% [85]
5 Years rr_AverageAnnualReturnYear05 11.49% [85]
10 Years rr_AverageAnnualReturnYear10 7.77% [85]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index   (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 25.96%
5 Years rr_AverageAnnualReturnYear05 15.16%
10 Years rr_AverageAnnualReturnYear10 11.48%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index(reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 5.53%
5 Years rr_AverageAnnualReturnYear05 1.10%
10 Years rr_AverageAnnualReturnYear10 1.81%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AONIX
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.72%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 74
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 231
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 401
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 895
Annual Return 2014 rr_AnnualReturn2014 5.54%
Annual Return 2015 rr_AnnualReturn2015 (1.12%)
Annual Return 2016 rr_AnnualReturn2016 5.61%
Annual Return 2017 rr_AnnualReturn2017 6.46%
Annual Return 2018 rr_AnnualReturn2018 (2.49%)
Annual Return 2019 rr_AnnualReturn2019 11.97%
Annual Return 2020 rr_AnnualReturn2020 9.42%
Annual Return 2021 rr_AnnualReturn2021 6.63%
Annual Return 2022 rr_AnnualReturn2022 (11.33%)
Annual Return 2023 rr_AnnualReturn2023 7.60%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 7.33%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.96%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (7.02%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 7.60%
5 Years rr_AverageAnnualReturnYear05 4.50%
10 Years rr_AverageAnnualReturnYear10 3.61%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 6.41%
5 Years rr_AverageAnnualReturnYear05 2.97%
10 Years rr_AverageAnnualReturnYear10 2.31%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 4.53%
5 Years rr_AverageAnnualReturnYear05 3.05%
10 Years rr_AverageAnnualReturnYear10 2.41%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AORHX
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.22%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 125
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 388
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 671
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,477
Label rr_AverageAnnualReturnLabel R Class1 Return Before Taxes [86]
1 Year rr_AverageAnnualReturnYear01 7.15% [86]
5 Years rr_AverageAnnualReturnYear05 4.00% [86]
10 Years rr_AverageAnnualReturnYear10 3.11% [86]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 20, 2015 [86]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Portfolio: Conservative
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 14% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 14.00%
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
One Choice Portfolio: Conservative is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy emphasizes investments in fixed-income securities and short-term investments, but maintains a sizeable portion of the fund’s assets in equity securities.
The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes over the long term as of the date of this prospectus.
Equity Securities (Stock Funds)45.0 %
U.S. Equity33.0 %
International Equity10.0 %
Real Estate2.0 %
Fixed-Income Securities (Bond Funds)49.0 %
Short-Term Investments (Short-Term Funds)6.0 %
The managers regularly review the fund and may make changes to the fund’s asset class allocations that deviate from the neutral mix to emphasize investments that they believe will provide the most favorable outlook for achieving the fund’s objective. The fund also may deviate from the neutral mix due to differences in asset class performance or prevailing market conditions. The following table shows the operating ranges within which the fund’s asset class allocations generally will vary over short-term periods.
 Equity Securities
(Stock Funds)		Fixed-Income Securities
(Bond Funds)		Short-Term Investments
(Short-Term Funds)
Operating Ranges39-51%38-55%2-20%
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Portfolio: Conservative is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy emphasizes investments in fixed-income securities and short-term investments, but maintains a sizeable portion of the fund’s assets in equity securities.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures 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 broad measures 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 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 (2Q 2020): 11.79% Lowest Performance Quarter (1Q 2020): -10.36%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 9.31%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
•Allocation Risk – The fund’s ability to achieve its investment objective depends in part on the managers’ skill in determining the funds’ asset class allocations and in selecting and weighting the underlying funds. The managers’ evaluations and assumptions regarding asset classes and underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. Shareholders of the fund will also indirectly bear their pro rata share of the expenses of such underlying funds. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by the inability or perceived inability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | MSCI ACWI IMI (reflects no deductions for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deductions for fees, expenses or taxes) [87]
Label rr_AverageAnnualReturnLabel MSCI ACWI IMI2(reflects no deductions for fees, expenses or taxes) [87]
1 Year rr_AverageAnnualReturnYear01 21.58% [87]
5 Years rr_AverageAnnualReturnYear05 11.49% [87]
10 Years rr_AverageAnnualReturnYear10 7.77% [87]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index   (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 25.96%
5 Years rr_AverageAnnualReturnYear05 15.16%
10 Years rr_AverageAnnualReturnYear10 11.48%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index   (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 5.53%
5 Years rr_AverageAnnualReturnYear05 1.10%
10 Years rr_AverageAnnualReturnYear10 1.81%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AOCIX
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.81%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.81%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 83
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 259
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 450
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,002
Annual Return 2014 rr_AnnualReturn2014 6.73%
Annual Return 2015 rr_AnnualReturn2015 (1.39%)
Annual Return 2016 rr_AnnualReturn2016 5.58%
Annual Return 2017 rr_AnnualReturn2017 11.09%
Annual Return 2018 rr_AnnualReturn2018 (4.88%)
Annual Return 2019 rr_AnnualReturn2019 16.07%
Annual Return 2020 rr_AnnualReturn2020 12.81%
Annual Return 2021 rr_AnnualReturn2021 9.03%
Annual Return 2022 rr_AnnualReturn2022 (14.00%)
Annual Return 2023 rr_AnnualReturn2023 10.52%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 9.31%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.79%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (10.36%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.52%
5 Years rr_AverageAnnualReturnYear05 6.29%
10 Years rr_AverageAnnualReturnYear10 4.77%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 9.48%
5 Years rr_AverageAnnualReturnYear05 4.48%
10 Years rr_AverageAnnualReturnYear10 3.24%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 6.30%
5 Years rr_AverageAnnualReturnYear05 4.51%
10 Years rr_AverageAnnualReturnYear10 3.35%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AORSX
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.81%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.31%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 134
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 416
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 719
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,578
Label rr_AverageAnnualReturnLabel R Class1 Return Before Taxes [88]
1 Year rr_AverageAnnualReturnYear01 10.06% [88]
5 Years rr_AverageAnnualReturnYear05 5.78% [88]
10 Years rr_AverageAnnualReturnYear10 4.25% [88]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 20, 2015 [88]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Portfolio: Moderate
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 11% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 11.00%
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
One Choice Portfolio: Moderate is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy emphasizes investments in equity securities, but maintains a sizeable portion of the fund’s assets in fixed-income securities and short-term investments.
The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes over the long term as of the date of this prospectus.
Equity Securities (Stock Funds)64.0 %
U.S. Equity43.5 %
International Equity18.0 %
Real Estate2.5 %
Fixed-Income Securities (Bond Funds)32.0 %
Short-Term Investments (Short-Term Funds)4.0 %
The managers regularly review the fund and may make changes to the fund’s asset class allocations that deviate from the neutral mix to emphasize investments that they believe will provide the most favorable outlook for achieving the fund’s objective. The fund also may deviate from the neutral mix due to differences in asset class performance or prevailing market conditions. The following table shows the operating ranges within which the fund’s asset class allocations generally will vary over short-term periods.
 Equity Securities
(Stock Funds)		Fixed-Income Securities
(Bond Funds)		Short-Term Investments
(Short-Term Funds)
Operating Ranges53-73%21-41%0-15%
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Portfolio: Moderate is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy emphasizes investments in equity securities, but maintains a sizeable portion of the fund’s assets in fixed-income securities and short-term investments.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures 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 broad measures 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 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 (2Q 2020): 15.53% Lowest Performance Quarter (1Q 2020): -14.44%

As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 11.83%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
•Allocation Risk – The fund’s ability to achieve its investment objective depends in part on the managers’ skill in determining the funds’ asset class allocations and in selecting and weighting the underlying funds. The managers’ evaluations and assumptions regarding asset classes and underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. Shareholders of the fund will also indirectly bear their pro rata share of the expenses of such underlying funds. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by the inability or perceived inability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price. Investing in securities of companies located in emerging market countries is generally riskier than investing in securities of companies located in developed foreign countries.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | MSCI ACWI IMI (reflects no deductions for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deductions for fees, expenses or taxes) [89]
Label rr_AverageAnnualReturnLabel MSCI ACWI IMI2(reflects no deductions for fees, expenses or taxes) [89]
1 Year rr_AverageAnnualReturnYear01 21.58% [89]
5 Years rr_AverageAnnualReturnYear05 11.49% [89]
10 Years rr_AverageAnnualReturnYear10 7.77% [89]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index   (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 25.96%
5 Years rr_AverageAnnualReturnYear05 15.16%
10 Years rr_AverageAnnualReturnYear10 11.48%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index   (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 5.53%
5 Years rr_AverageAnnualReturnYear05 1.10%
10 Years rr_AverageAnnualReturnYear10 1.81%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AOMIX
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.87%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.87%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 89
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 278
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 483
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,073
Annual Return 2014 rr_AnnualReturn2014 6.98%
Annual Return 2015 rr_AnnualReturn2015 (1.56%)
Annual Return 2016 rr_AnnualReturn2016 6.45%
Annual Return 2017 rr_AnnualReturn2017 15.43%
Annual Return 2018 rr_AnnualReturn2018 (6.66%)
Annual Return 2019 rr_AnnualReturn2019 20.16%
Annual Return 2020 rr_AnnualReturn2020 16.07%
Annual Return 2021 rr_AnnualReturn2021 11.83%
Annual Return 2022 rr_AnnualReturn2022 (16.30%)
Annual Return 2023 rr_AnnualReturn2023 13.03%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 11.83%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.53%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.44%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.03%
5 Years rr_AverageAnnualReturnYear05 8.09%
10 Years rr_AverageAnnualReturnYear10 5.95%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 12.10%
5 Years rr_AverageAnnualReturnYear05 5.98%
10 Years rr_AverageAnnualReturnYear10 4.23%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 7.83%
5 Years rr_AverageAnnualReturnYear05 5.97%
10 Years rr_AverageAnnualReturnYear10 4.30%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AORMX
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.87%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.37%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 140
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 435
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 751
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,645
Label rr_AverageAnnualReturnLabel R Class 1 Return Before Taxes [90]
1 Year rr_AverageAnnualReturnYear01 12.46% [90]
5 Years rr_AverageAnnualReturnYear05 7.55% [90]
10 Years rr_AverageAnnualReturnYear10 5.42% [90]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 20, 2015 [90]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Portfolio: Aggressive
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 8% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 8.00%
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
One Choice Portfolio: Aggressive is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy emphasizes investments in equity securities, but maintains a portion of the fund’s assets in fixed-income securities and short-term investments.
The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes over the long term as of the date of this prospectus.
Equity Securities (Stock Funds)79.0 %
U.S. Equity54.0 %
International Equity22.0 %
Real Estate3.0 %
Fixed-Income Securities (Bond Funds)20.0 %
Short-Term Investments (Short-Term Funds)1.0 %
The managers regularly review the fund and may make changes to the fund’s asset class allocations that deviate from the neutral mix to emphasize investments that they believe will provide the most favorable outlook for achieving the fund’s objective. The fund also may deviate from the neutral mix due to differences in asset class performance or prevailing market conditions. The following table shows the operating ranges within which the fund’s asset class allocations generally will vary over short-term periods.
 Equity Securities
(Stock Funds)		Fixed-Income Securities
(Bond Funds)		Short-Term Investments
(Short-Term Funds)
Operating Ranges60-90%10-30%0-15%
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Portfolio: Aggressive is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy emphasizes investments in equity securities, but maintains a portion of the fund’s assets in fixed-income securities and short-term investments.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures 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 broad measures 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 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 (2Q 2020): 18.50% Lowest Performance Quarter (1Q 2020): -17.90%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 13.74%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
•Allocation Risk – The fund’s ability to achieve its investment objective depends in part on the managers’ skill in determining the funds’ asset class allocations and in selecting and weighting the underlying funds. The managers’ evaluations and assumptions regarding asset classes and underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. Shareholders of the fund will also indirectly bear their pro rata share of the expenses of such underlying funds. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Interest Rate Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Interest Rate Risk – Generally, when interest rates rise, the value of an underlying fund’s fixed-income securities will decline. The opposite is true when interest rates decline. Underlying funds with longer weighted average maturities are more sensitive to interest rate changes. A period of rising interest rates may negatively affect the performance of underlying fixed-income funds.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Credit Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Credit Risk – The value of an underlying fund’s fixed-income securities will be affected adversely by the inability or perceived inability of the issuers of these securities to make interest and principal payments as they become due. Changes in the credit rating of a fixed-income security held by an underlying fund could have a similar effect.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price. Investing in securities of companies located in emerging market countries is generally riskier than investing in securities of companies located in developed foreign countries.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | MSCI ACWI IMI (reflects no deductions for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deductions for fees, expenses or taxes) [91]
Label rr_AverageAnnualReturnLabel MSCI ACWI IMI2(reflects no deductions for fees, expenses or taxes) [91]
1 Year rr_AverageAnnualReturnYear01 21.58% [91]
5 Years rr_AverageAnnualReturnYear05 11.49% [91]
10 Years rr_AverageAnnualReturnYear10 7.77% [91]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index   (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 25.96%
5 Years rr_AverageAnnualReturnYear05 15.16%
10 Years rr_AverageAnnualReturnYear10 11.48%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Bloomberg U.S. Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg U.S. Aggregate Bond Index   (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 5.53%
5 Years rr_AverageAnnualReturnYear05 1.10%
10 Years rr_AverageAnnualReturnYear10 1.81%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AOGIX
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.93%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.93%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 95
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 297
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 515
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,143
Annual Return 2014 rr_AnnualReturn2014 7.31%
Annual Return 2015 rr_AnnualReturn2015 (1.26%)
Annual Return 2016 rr_AnnualReturn2016 6.89%
Annual Return 2017 rr_AnnualReturn2017 19.13%
Annual Return 2018 rr_AnnualReturn2018 (8.08%)
Annual Return 2019 rr_AnnualReturn2019 23.86%
Annual Return 2020 rr_AnnualReturn2020 18.18%
Annual Return 2021 rr_AnnualReturn2021 13.88%
Annual Return 2022 rr_AnnualReturn2022 (17.21%)
Annual Return 2023 rr_AnnualReturn2023 15.15%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 13.74%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.50%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (17.90%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.15%
5 Years rr_AverageAnnualReturnYear05 9.71%
10 Years rr_AverageAnnualReturnYear10 7.02%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 14.35%
5 Years rr_AverageAnnualReturnYear05 7.28%
10 Years rr_AverageAnnualReturnYear10 5.00%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 9.14%
5 Years rr_AverageAnnualReturnYear05 7.29%
10 Years rr_AverageAnnualReturnYear10 5.14%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AORYX
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.93%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.43%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 146
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 453
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 782
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,712
Label rr_AverageAnnualReturnLabel R Class1 Return Before Taxes [92]
1 Year rr_AverageAnnualReturnYear01 14.55% [92]
5 Years rr_AverageAnnualReturnYear05 9.17% [92]
10 Years rr_AverageAnnualReturnYear10 6.48% [92]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 20, 2015 [92]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading One Choice Portfolio: Very Aggressive
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The fund seeks the highest total return consistent with its asset mix.
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, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.
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
Because the fund buys and sells shares of other American Century mutual funds (the underlying funds) directly from the issuers, the fund is not expected to incur transaction costs directly. However, as a shareholder in the underlying funds, the fund indirectly pays transaction costs, such as commissions, when the underlying funds buy and sell securities (or “turn over” their portfolios). 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 8% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 8.00%
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
One Choice Portfolio: Very Aggressive is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy generally invests in equity securities. However, if the portfolio managers believe it is prudent, the fund may invest a portion of its assets in fixed-income securities and short-term investments.
The following table indicates the fund’s neutral mix; that is, how the fund’s investments generally will be allocated among the major asset classes over the long term as of the date of this prospectus.
Equity Securities (Stock Funds)100.0 %
U.S. Equity63.5 %
International Equity32.5 %
Real Estate4.0 %
Fixed-Income Securities (Bond Funds)0.0 %
Short-Term Investments (Short-Term Funds)0.0 %
The managers regularly review the fund and may make changes to the fund’s asset class allocations that deviate from the neutral mix to emphasize investments that they believe will provide the most favorable outlook for achieving the fund’s objective. The fund also may deviate from the neutral mix due to differences in asset class performance or prevailing market conditions. The following table shows the operating ranges within which the fund’s asset class allocations generally will vary over short-term periods.
 Equity Securities
(Stock Funds)		Fixed-Income Securities
(Bond Funds)		Short-Term Investments
(Short-Term Funds)
Operating Ranges75-100%0-10%0-15%
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration One Choice Portfolio: Very Aggressive is a “fund of funds,” meaning that it seeks to achieve its objective by investing in other American Century Investments mutual funds (the underlying funds) that represent a variety of asset classes and investment styles. The fund’s asset allocation strategy generally invests in equity securities. However, if the portfolio managers believe it is prudent, the fund may invest a portion of its assets in fixed-income securities and short-term investments.
Risk [Heading] rr_RiskHeading Principal Risks
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 broad measures 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 broad measures 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 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 (2Q 2020): 22.38% Lowest Performance Quarter (1Q 2020): -21.64%
As of September 30, 2024, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 16.15%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total ReturnsFor the calendar year ended December 31, 2023
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Principal Loss Risk – 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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
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.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | Allocation Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock
•Allocation Risk – The fund’s ability to achieve its investment objective depends in part on the managers’ skill in determining the funds’ asset class allocations and in selecting and weighting the underlying funds. The managers’ evaluations and assumptions regarding asset classes and underlying funds may differ from actual market conditions.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | Fund Of Funds Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Fund of Funds Risks – The fund’s performance and risks reflect the performance and risks of the underlying American Century Investments funds in which it invests. Shareholders of the fund will also indirectly bear their pro rata share of the expenses of such underlying funds. The fund’s investment in other American Century Investments funds may create a conflict of interest for the fund’s advisor.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | “Growth” And “Value” Style Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock “Growth” and “Value” Style Risks – The underlying funds represent a mix of investment styles, each of which has risks associated with it. Growth stocks can be volatile and may lack dividends that can cushion share prices during market declines. Value stocks may continue to be undervalued by the market for long periods of time.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | Small- And Mid-Cap Stock Risks Member  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Small- and Mid-Cap Stock Risks – Stocks of smaller companies may be more volatile than larger-company stocks. Smaller companies may have limited financial resources, product lines and markets, and their securities may trade less frequently and in more limited volumes than the securities of larger companies, which could lead to higher transaction costs. To the extent an underlying fund invests in these companies, it may take on more risk.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | Foreign Securities Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Foreign Securities Risk – Some of the underlying funds invest in foreign securities, which are generally riskier than U.S. securities. Political events, social and economic events, natural disasters and public health emergencies occurring in a country where the fund invests could cause the fund's investments in that country to experience gains or losses. Securities of foreign issuers may be less liquid, more volatile and harder to value than U.S. securities. Fluctuations in currency exchange rates also may affect an underlying fund’s share price. Investing in securities of companies located in emerging market countries is generally riskier than investing in securities of companies located in developed foreign countries.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock Market Risk – The value of the fund’s shares will go up and down based on the performance of the underlying funds in which it invests. The value of the underlying funds’ shares will, in turn, fluctuate based on the performance of the securities they own and other factors generally affecting the securities market. Market risks, including political, regulatory, economic and social developments, can affect the value of the fund’s investments. Natural disasters, public health emergencies, war, terrorism and other unforeseeable events may lead to increased market volatility and may have adverse long-term effects on world economies and markets generally.
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | MSCI ACWI IMI (reflects no deductions for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deductions for fees, expenses or taxes) [93]
Label rr_AverageAnnualReturnLabel MSCI ACWI IMI2(reflects no deductions for fees, expenses or taxes) [93]
1 Year rr_AverageAnnualReturnYear01 21.58% [93]
5 Years rr_AverageAnnualReturnYear05 11.49% [93]
10 Years rr_AverageAnnualReturnYear10 7.77% [93]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | Russell 3000® Index (reflects no deduction for fees, expenses or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index   (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 25.96%
5 Years rr_AverageAnnualReturnYear05 15.16%
10 Years rr_AverageAnnualReturnYear10 11.48%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | INVESTOR CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AOVIX
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 1.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.03%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 105
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 328
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 569
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,259
Annual Return 2014 rr_AnnualReturn2014 7.96%
Annual Return 2015 rr_AnnualReturn2015 (1.30%)
Annual Return 2016 rr_AnnualReturn2016 7.40%
Annual Return 2017 rr_AnnualReturn2017 22.78%
Annual Return 2018 rr_AnnualReturn2018 (9.99%)
Annual Return 2019 rr_AnnualReturn2019 27.64%
Annual Return 2020 rr_AnnualReturn2020 21.15%
Annual Return 2021 rr_AnnualReturn2021 15.87%
Annual Return 2022 rr_AnnualReturn2022 (19.52%)
Annual Return 2023 rr_AnnualReturn2023 17.28%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2024
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 16.15%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 22.38%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (21.64%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.28%
5 Years rr_AverageAnnualReturnYear05 11.08%
10 Years rr_AverageAnnualReturnYear10 7.90%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 16.75%
5 Years rr_AverageAnnualReturnYear05 8.96%
10 Years rr_AverageAnnualReturnYear10 6.01%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus [Line Items] rr_ProspectusLineItems  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 10.45%
5 Years rr_AverageAnnualReturnYear05 8.54%
10 Years rr_AverageAnnualReturnYear10 5.94%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | R CLASS  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol AORVX
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 1.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.53%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 156
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 484
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 835
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,822
Label rr_AverageAnnualReturnLabel R Class1 Return Before Taxes [94]
1 Year rr_AverageAnnualReturnYear01 16.66% [94]
5 Years rr_AverageAnnualReturnYear05 10.53% [94]
10 Years rr_AverageAnnualReturnYear10 7.36% [94]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 20, 2015 [94]
[1] The fund’s broad-based securities market index changed from the S&P Target Date Retirement Income Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[2] The management fee has been restated to reflect current fees.
[3] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[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] C Class shares automatically convert to A Class shares after approximately eight years. All returns for periods greater than eight years reflect this conversion.
[6] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice In Retirement Portfolio R6. Such historical performance began on July 31, 2013. The R6 Class of the fund acquired all of the assets of the One Choice In Retirement Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[7] The fund’s broad-based securities market index changed from the S&P Target Date to 2025 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[8] The management fee has been restated to reflect current fees.
[9] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[10] 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.
[11] C Class shares automatically convert to A Class shares after approximately eight years. All returns for periods greater than eight years reflect this conversion.
[12] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice 2025 Portfolio R6. Such historical performance began on July 31, 2013. The R6 Class of the fund acquired all of the assets of the One Choice 2025 Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[13] The fund’s broad-based securities market index changed from the S&P Target Date to 2030 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[14] The management fee has been restated to reflect current fees.
[15] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[16] 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.
[17] C Class shares automatically convert to A Class shares after approximately eight years. All returns for periods greater than eight years reflect this conversion.
[18] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice 2030 Portfolio R6. Such historical performance began on July 31, 2013. The R6 Class of the fund acquired all of the assets of the One Choice 2030 Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[19] The fund’s broad-based securities market index changed from the S&P Target Date to 2035 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[20] The management fee has been restated to reflect current fees.
[21] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[22] 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.
[23] C Class shares automatically convert to A Class shares after approximately eight years. All returns for periods greater than eight years reflect this conversion.
[24] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice 2035 Portfolio R6. Such historical performance began on July 31, 2013. The R6 Class of the fund acquired all of the assets of the One Choice 2035 Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[25] The fund’s broad-based securities market index changed from the S&P Target Date to 2040 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[26] The management fee has been restated to reflect current fees.
[27] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[28] 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.
[29] C Class shares automatically convert to A Class shares after approximately eight years. All returns for periods greater than eight years reflect this conversion.
[30] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice 2040 Portfolio R6. Such historical performance began on July 31, 2013. The R6 Class of the fund acquired all of the assets of the One Choice 2040 Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[31] The fund’s broad-based securities market index changed from the S&P Target Date to 2045 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[32] The management fee has been restated to reflect current fees.
[33] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[34] 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.
[35] C Class shares automatically convert to A Class shares after approximately eight years. All returns for periods greater than eight years reflect this conversion.
[36] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice 2045 Portfolio R6. Such historical performance began on July 31, 2013. The R6 Class of the fund acquired all of the assets of the One Choice 2045 Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[37] The fund’s broad-based securities market index changed from the S&P Target Date to 2050 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[38] The management fee has been restated to reflect current fees.
[39] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[40] 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.
[41] C Class shares automatically convert to A Class shares after approximately eight years. All returns for periods greater than eight years reflect this conversion.
[42] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice 2050 Portfolio R6. Such historical performance began on July 31, 2013. The R6 Class of the fund acquired all of the assets of the One Choice 2050 Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[43] The fund’s broad-based securities market index changed from the S&P Target Date to 2055 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[44] The management fee has been restated to reflect current fees.
[45] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[46] 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.
[47] C Class shares automatically convert to A Class shares after approximately eight years. All returns for periods greater than eight years reflect this conversion.
[48] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice 2055 Portfolio R6. Such historical performance began on July 31, 2013. The R6 Class of the fund acquired all of the assets of the One Choice 2055 Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[49] The fund’s broad-based securities market index changed from the S&P Target Date to 2060 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[50] The management fee has been restated to reflect current fees.
[51] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[52] 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.
[53] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice 2060 Portfolio R6. Such historical performance began on September 30, 2015. The R6 Class of the fund acquired all of the assets of the One Choice 2060 Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[54] The fund’s broad-based securities market index changed from the S&P Target Date to 2065+ Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[55] The management fee has been restated to reflect current fees.
[56] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2025 and cannot terminate it prior to such date without the approval of the Board of Directors.
[57] 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.
[58] The fund’s broad-based securities market index changed from the S&P Target Date to 2015 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[59] The advisor will waive a portion of the fund’s management fee equal to the expenses attributable to the management fees of American Century-advised underlying funds. The amount of this waiver will fluctuate depending on the fund’s daily allocations to such funds. This waiver is expected to remain in effect permanently, and it cannot be terminated without the approval of the Board of Directors.
[60] 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.
[61] The fund’s broad-based securities market index changed from the S&P Target Date to 2020 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[62] The advisor will waive a portion of the fund’s management fee equal to the expenses attributable to the management fees of American Century-advised underlying funds. The amount of this waiver will fluctuate depending on the fund’s daily allocations to such funds. This waiver is expected to remain in effect permanently, and it cannot be terminated without the approval of the Board of Directors.
[63] 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.
[64] The fund’s broad-based securities market index changed from the S&P Target Date to 2025 Index as a result of recent regulatory changes requiring that represent the overall applicable securities market.
[65] The advisor will waive a portion of the fund’s management fee equal to the expenses attributable to the management fees of American Century-advised underlying funds. The amount of this waiver will fluctuate depending on the fund’s daily allocations to such funds. This waiver is expected to remain in effect permanently, and it cannot be terminated without the approval of the Board of Directors.
[66] 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.
[67] The fund’s broad-based securities market index changed from the S&P Target Date to 2030 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[68] The advisor will waive a portion of the fund’s management fee equal to the expenses attributable to the management fees of American Century-advised underlying funds. The amount of this waiver will fluctuate depending on the fund’s daily allocations to such funds. This waiver is expected to remain in effect permanently, and it cannot be terminated without the approval of the Board of Directors.
[69] 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.
[70] The fund’s broad-based securities market index changed from the S&P Target Date to 2035 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[71] The advisor will waive a portion of the fund’s management fee equal to the expenses attributable to the management fees of American Century-advised underlying funds. The amount of this waiver will fluctuate depending on the fund’s daily allocations to such funds. This waiver is expected to remain in effect permanently, and it cannot be terminated without the approval of the Board of Directors.
[72] 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.
[73] The fund’s broad-based securities market index changed from the S&P Target Date to 2040 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[74] 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.
[75] The fund’s broad-based securities market index changed from the S&P Target Date to 2045 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[76] 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.
[77] The fund’s broad-based securities market index changed from the S&P Target Date to 2050 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[78] 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.
[79] The fund’s broad-based securities market index changed from the S&P Target Date to 2055 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[80] 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.
[81] The fund’s broad-based securities market index changed from the S&P Target Date to 2060 Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[82] 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.
[83] The fund’s broad-based securities market index changed from the S&P Target Date to 2065+ Index as a result of recent regulatory changes requiring that such index represent the overall applicable securities market.
[84] 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.
[85] The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
[86] Historical performance for R Class prior to its inception (March 20, 2015) is based on the performance of Investor Class shares. R Class performance has been adjusted to reflect differences in sales charges, if applicable, and expenses between classes.
[87] The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
[88] Historical performance for R Class prior to its inception (March 20, 2015) is based on the performance of Investor Class shares. R Class performance has been adjusted to reflect differences in sales charges, if applicable, and expenses between classes.
[89] The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
[90] Historical performance for R Class prior to its inception (March 20, 2015) is based on the performance of Investor Class shares. R Class performance has been adjusted to reflect differences in sales charges, if applicable, and expenses between classes.
[91] The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
[92] Historical performance for R Class prior to its inception (March 20, 2015) is based on the performance of Investor Class shares. R Class performance has been adjusted to reflect differences in sales charges, if applicable, and expenses between classes.
[93] The fund’s broad-based securities market index changed from the Russell 3000® Index to the MSCI ACWI IMI, which the advisor believes is more reflective of the fund's strategy as compared to the Russell 3000® Index.
[94] Historical performance for R Class prior to its inception (March 20, 2015) is based on the performance of Investor Class shares. R Class performance has been adjusted to reflect differences in sales charges, if applicable, and expenses between classes.