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Label Element Value
Prospectus: rr_ProspectusTable  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Jul. 31, 2018
Entity Registrant Name dei_EntityRegistrantName AMERICAN CENTURY ASSET ALLOCATION PORTFOLIOS, INC.
Central Index Key dei_EntityCentralIndexKey 0001293210
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Nov. 28, 2018
Document Effective Date dei_DocumentEffectiveDate Dec. 01, 2018
Prospectus Date rr_ProspectusDate Dec. 01, 2018
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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
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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
45.00
%
NT Core Equity Plus Fund
2.67
%
NT Disciplined Growth Fund
1.73
%
NT Emerging Markets Fund
0.00
%
NT Equity Growth Fund
8.01
%
NT Global Real Estate Fund
1.01
%
NT Growth Fund
5.18
%
NT Heritage Fund
1.89
%
NT International Growth Fund
4.16
%
NT International Small-Mid Cap Fund
0.48
%
NT International Value Fund
4.75
%
NT Large Company Value Fund
9.11
%
NT Mid Cap Value Fund
4.08
%
NT Non-U.S. Intrinsic Value Fund
0.00
%
NT Small Company Fund
1.93
%
 
Fixed-Income Securities (Bond Funds)
45.00
%
 
Emerging Markets Debt Fund
1.13
%
 
Global Bond Fund
7.88
%
 
Inflation-Adjusted Bond Fund
3.04
%
 
International Bond Fund
2.25
%
 
NT Diversified Bond Fund
20.23
%
 
NT High Income Fund
3.38
%
 
Short Duration Inflation Protection Bond Fund
7.09
%
 
 
 
 
Cash Equivalents (Money Market Fund)
10.00
%
 
U.S. Government Money Market Fund
10.00
%
 
 
 
 
 
 
 
 
 
 
 
 
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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
•
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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 9.30% Lowest Performance Quarter (4Q 2008): -9.20%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 2.55%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | S & P Target Date Retirement Index  
Prospectus: rr_ProspectusTable  
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 8.54%
5 Years rr_AverageAnnualReturnYear05 4.86%
10 Years rr_AverageAnnualReturnYear10 4.11%
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.03%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.77%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 79
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 253
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 442
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 987
Annual Return 2008 rr_AnnualReturn2008 (16.57%)
Annual Return 2009 rr_AnnualReturn2009 16.42%
Annual Return 2010 rr_AnnualReturn2010 10.07%
Annual Return 2011 rr_AnnualReturn2011 3.58%
Annual Return 2012 rr_AnnualReturn2012 10.13%
Annual Return 2013 rr_AnnualReturn2013 11.11%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 2.55%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.30%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (9.20%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.21%
5 Years rr_AverageAnnualReturnYear05 6.25%
10 Years rr_AverageAnnualReturnYear10 5.14%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 9.23%
5 Years rr_AverageAnnualReturnYear05 5.14%
10 Years rr_AverageAnnualReturnYear10 4.16%
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: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 6.22%
5 Years rr_AverageAnnualReturnYear05 4.58%
10 Years rr_AverageAnnualReturnYear10 3.77%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.59% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.57%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 58
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 194
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 341
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 770
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.35%
5 Years rr_AverageAnnualReturnYear05 6.46%
10 Years rr_AverageAnnualReturnYear10 5.35%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.03%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.02%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 673
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 888
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,119
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,781
Label rr_AverageAnnualReturnLabel A Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 3.61% [4]
5 Years rr_AverageAnnualReturnYear05 4.74% [4]
10 Years rr_AverageAnnualReturnYear10 4.26% [4]
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004 [4]
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.03%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.77%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 180
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 564
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 973
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,111
Label rr_AverageAnnualReturnLabel C Class2 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.14% [5]
5 Years rr_AverageAnnualReturnYear05 5.22% [5]
10 Years rr_AverageAnnualReturnYear10 4.10% [5]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [5]
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.03%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.27%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 130
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 410
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 711
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,564
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.58%
5 Years rr_AverageAnnualReturnYear05 5.72%
10 Years rr_AverageAnnualReturnYear10 4.61%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.55%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.13%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.42%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 43
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 163
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 295
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 677
Label rr_AverageAnnualReturnLabel R6 Class3 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.47% [6]
Since Inception rr_AverageAnnualReturnSinceInception 5.93% [6]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [6]
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO  
Prospectus: rr_ProspectusTable  
Risk/Return [Heading] rr_RiskReturnHeading One Choice® 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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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
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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2020 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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
46.00
%
NT Core Equity Plus Fund
2.69
%
NT Disciplined Growth Fund
1.78
%
NT Emerging Markets Fund
0.13
%
NT Equity Growth Fund
8.08
%
NT Global Real Estate Fund
1.05
%
NT Growth Fund
5.33
%
NT Heritage Fund
1.98
%
NT International Growth Fund
4.24
%
NT International Small-Mid Cap Fund
0.56
%
NT International Value Fund
4.72
%
NT Large Company Value Fund
9.14
%
NT Mid Cap Value Fund
4.23
%
NT Non-U.S. Intrinsic Value Fund
0.11
%
NT Small Company Fund
1.96
%
 
Fixed-Income Securities (Bond Funds)
44.50
%
 
Emerging Markets Debt Fund
1.22
%
 
Global Bond Fund
7.79
%
 
Inflation-Adjusted Bond Fund
3.28
%
 
International Bond Fund
2.23
%
 
NT Diversified Bond Fund
20.02
%
 
NT High Income Fund
3.45
%
 
Short Duration Inflation Protection Bond Fund
6.51
%
 
 
 
 
Cash Equivalents (Money Market Fund)
9.50
%
 
U.S. Government Money Market Fund
9.50
%
 
 
 
 
 
 
 
 
 
 
 
 
The target date in the fund name (2020) 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 cash. 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, 45% bond funds and 10% money market 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.
glidepathimagea85.gif
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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
•
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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 11.07% Lowest Performance Quarter (4Q 2008): -11.97%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 2.56%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 2020 PORTFOLIO | S&P Target Date To 2020 Index  
Prospectus: rr_ProspectusTable  
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 11.16%
5 Years rr_AverageAnnualReturnYear05 6.70%
Since Inception rr_AverageAnnualReturnSinceInception 5.04%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol ARBVX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.03%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.77%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 79
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 253
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 442
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 987
Annual Return 2009 rr_AnnualReturn2009 20.11%
Annual Return 2010 rr_AnnualReturn2010 11.70%
Annual Return 2011 rr_AnnualReturn2011 2.50%
Annual Return 2012 rr_AnnualReturn2012 11.47%
Annual Return 2013 rr_AnnualReturn2013 12.58%
Annual Return 2014 rr_AnnualReturn2014 6.61%
Annual Return 2015 rr_AnnualReturn2015 (1.61%)
Annual Return 2016 rr_AnnualReturn2016 6.07%
Annual Return 2017 rr_AnnualReturn2017 10.92%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 2.56%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.07%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (11.97%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.92%
5 Years rr_AverageAnnualReturnYear05 6.80%
Since Inception rr_AverageAnnualReturnSinceInception 5.44%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 9.95%
5 Years rr_AverageAnnualReturnYear05 5.69%
Since Inception rr_AverageAnnualReturnSinceInception 4.57%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 6.62%
5 Years rr_AverageAnnualReturnYear05 5.03%
Since Inception rr_AverageAnnualReturnSinceInception 4.08%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol ARBSX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.59% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.57%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 58
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 194
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 341
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 770
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.15%
5 Years rr_AverageAnnualReturnYear05 7.01%
Since Inception rr_AverageAnnualReturnSinceInception 5.65%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol ARBMX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.03%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.02%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 673
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 888
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,119
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,781
Label rr_AverageAnnualReturnLabel A Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 4.28% [4]
5 Years rr_AverageAnnualReturnYear05 5.27% [4]
Since Inception rr_AverageAnnualReturnSinceInception 4.53% [4]
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008 [4]
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol ARNCX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.03%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.77%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 180
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 564
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 973
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,111
Label rr_AverageAnnualReturnLabel C Class2 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.87% [5]
5 Years rr_AverageAnnualReturnYear05 5.75% [5]
Since Inception rr_AverageAnnualReturnSinceInception 4.40% [5]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [5]
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol ARBRX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.77% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.03%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.27%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 130
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 410
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 711
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,564
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.47%
5 Years rr_AverageAnnualReturnYear05 6.28%
Since Inception rr_AverageAnnualReturnSinceInception 4.92%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol ARBDX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.55%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.13%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.42%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 43
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 163
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 295
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 677
Label rr_AverageAnnualReturnLabel R6 Class3 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.12% [7]
Since Inception rr_AverageAnnualReturnSinceInception 6.33% [7]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [7]
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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
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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
51.00
%
NT Core Equity Plus Fund
2.79
%
NT Disciplined Growth Fund
2.01
%
NT Emerging Markets Fund
0.92
%
NT Equity Growth Fund
8.36
%
NT Global Real Estate Fund
1.26
%
NT Growth Fund
6.02
%
NT Heritage Fund
2.53
%
NT International Growth Fund
4.64
%
NT International Small-Mid Cap Fund
0.93
%
NT International Value Fund
4.47
%
NT Large Company Value Fund
9.32
%
NT Mid Cap Value Fund
4.92
%
NT Non-U.S. Intrinsic Value Fund
0.70
%
NT Small Company Fund
2.13
%
 
Fixed-Income Securities (Bond Funds)
42.00
%
 
Emerging Markets Debt Fund
1.68
%
 
Global Bond Fund
7.35
%
 
Inflation-Adjusted Bond Fund
4.18
%
 
International Bond Fund
2.10
%
 
NT Diversified Bond Fund
18.90
%
 
NT High Income Fund
3.78
%
 
Short Duration Inflation Protection Bond Fund
4.01
%
 
 
 
 
Cash Equivalents (Money Market Fund)
7.00
%
 
U.S. Government Money Market Fund
7.00
%
 
 
 
 
 
 
 
 
 
 
 
 
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 cash. 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, 45% bond funds and 10% money market 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.
glidepathimagea85.gif
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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
•
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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. 
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. 
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance 
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 11.70% Lowest Performance Quarter (4Q 2008): -13.92%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 2.69%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | S&P Target To 2025 Index  
Prospectus: rr_ProspectusTable  
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 12.94%
5 Years rr_AverageAnnualReturnYear05 7.58%
10 Years rr_AverageAnnualReturnYear10 4.93%
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.83%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.79%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 81
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 261
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 457
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,022
Annual Return 2008 rr_AnnualReturn2008 (25.02%)
Annual Return 2009 rr_AnnualReturn2009 21.24%
Annual Return 2010 rr_AnnualReturn2010 12.57%
Annual Return 2011 rr_AnnualReturn2011 1.77%
Annual Return 2012 rr_AnnualReturn2012 12.14%
Annual Return 2013 rr_AnnualReturn2013 14.04%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 2.69%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.70%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.92%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.27%
5 Years rr_AverageAnnualReturnYear05 7.43%
10 Years rr_AverageAnnualReturnYear10 5.27%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 11.24%
5 Years rr_AverageAnnualReturnYear05 6.21%
10 Years rr_AverageAnnualReturnYear10 4.31%
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: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 7.46%
5 Years rr_AverageAnnualReturnYear05 5.52%
10 Years rr_AverageAnnualReturnYear10 3.91%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.65%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
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 202
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 357
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 805
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.49%
5 Years rr_AverageAnnualReturnYear05 7.64%
10 Years rr_AverageAnnualReturnYear10 5.48%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.08%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.04%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 675
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 896
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,133
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,813
Label rr_AverageAnnualReturnLabel A Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 5.57% [4]
5 Years rr_AverageAnnualReturnYear05 5.92% [4]
10 Years rr_AverageAnnualReturnYear10 4.39% [4]
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004 [4]
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.83%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.79%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 182
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 573
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 987
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,142
Label rr_AverageAnnualReturnLabel C Class2 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.17% [5]
5 Years rr_AverageAnnualReturnYear05 6.36% [5]
10 Years rr_AverageAnnualReturnYear10 4.23% [5]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [5]
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.80% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.33%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.04%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.29%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 132
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 418
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 726
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,597
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.71%
5 Years rr_AverageAnnualReturnYear05 6.89%
10 Years rr_AverageAnnualReturnYear10 4.74%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.54% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.13%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.44%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 45
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 170
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 306
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 702
Label rr_AverageAnnualReturnLabel R6 Class3 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.56% [8]
Since Inception rr_AverageAnnualReturnSinceInception 6.90% [8]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [8]
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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 16% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 16.00%
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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
56.25
%
NT Core Equity Plus Fund
2.86
%
NT Disciplined Growth Fund
2.22
%
NT Emerging Markets Fund
2.00
%
NT Equity Growth Fund
8.59
%
NT Global Real Estate Fund
1.50
%
NT Growth Fund
6.66
%
NT Heritage Fund
3.27
%
NT International Growth Fund
4.99
%
NT International Small-Mid Cap Fund
1.34
%
NT International Value Fund
4.11
%
NT Large Company Value Fund
9.53
%
NT Mid Cap Value Fund
5.54
%
NT Non-U.S. Intrinsic Value Fund
1.35
%
NT Small Company Fund
2.29
%
 
Fixed-Income Securities (Bond Funds)
38.75
%
 
Emerging Markets Debt Fund
2.03
%
 
Global Bond Fund
6.88
%
 
Inflation-Adjusted Bond Fund
4.45
%
 
International Bond Fund
1.74
%
 
NT Diversified Bond Fund
17.64
%
 
NT High Income Fund
3.97
%
 
Short Duration Inflation Protection Bond Fund
2.04
%
 
 
 

 
Cash Equivalents (Money Market Fund)
5.00
%
 
U.S. Government Money Market Fund
5.00
%
 
 
 
 
 
 
 
 
 
 
 
 
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 cash. 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, 45% bond funds and 10% money market 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.
glidepathimagea85.gif
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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. 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.
•
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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown. 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown. 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 12.53% Lowest Performance Quarter (3Q 2011): -10.33%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 2.93%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | S&P Target Date To 2030  
Prospectus: rr_ProspectusTable  
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 14.76%
5 Years rr_AverageAnnualReturnYear05 8.44%
Since Inception rr_AverageAnnualReturnSinceInception 5.55%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.86%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.81%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 83
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 270
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 472
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,056
Annual Return 2009 rr_AnnualReturn2009 22.88%
Annual Return 2010 rr_AnnualReturn2010 13.39%
Annual Return 2011 rr_AnnualReturn2011 1.04%
Annual Return 2012 rr_AnnualReturn2012 12.79%
Annual Return 2013 rr_AnnualReturn2013 15.86%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 2.93%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 12.53%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (10.33%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.51%
5 Years rr_AverageAnnualReturnYear05 8.15%
Since Inception rr_AverageAnnualReturnSinceInception 5.82%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 12.55%
5 Years rr_AverageAnnualReturnYear05 6.99%
Since Inception rr_AverageAnnualReturnSinceInception 4.98%
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: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 8.13%
5 Years rr_AverageAnnualReturnYear05 6.13%
Since Inception rr_AverageAnnualReturnSinceInception 4.42%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.64% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.67%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.61%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 62
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 209
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 829
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.74%
5 Years rr_AverageAnnualReturnYear05 8.35%
Since Inception rr_AverageAnnualReturnSinceInception 6.02%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.11%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.06%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 677
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 903
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,147
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,845
Label rr_AverageAnnualReturnLabel A Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 6.72% [4]
5 Years rr_AverageAnnualReturnYear05 6.60% [4]
Since Inception rr_AverageAnnualReturnSinceInception 4.89% [4]
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008 [4]
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.86%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.81%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 184
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 581
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,002
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,173
Label rr_AverageAnnualReturnLabel C Class2 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.32% [5]
5 Years rr_AverageAnnualReturnYear05 7.07% [5]
Since Inception rr_AverageAnnualReturnSinceInception 4.76% [5]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [5]
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.83% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.36%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.31%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 134
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 427
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 741
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,630
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.95%
5 Years rr_AverageAnnualReturnYear05 7.62%
Since Inception rr_AverageAnnualReturnSinceInception 5.28%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.56% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.59%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.13%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.46%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 47
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 176
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 317
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 726
Label rr_AverageAnnualReturnLabel R6 Class3 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.74% [9]
Since Inception rr_AverageAnnualReturnSinceInception 7.41% [9]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [9]
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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 16% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 16.00%
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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies 
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
62.50
%
NT Core Equity Plus Fund
2.96
%
NT Disciplined Growth Fund
2.43
%
NT Emerging Markets Fund
3.45
%
NT Equity Growth Fund
8.87
%
NT Global Real Estate Fund
1.78
%
NT Growth Fund
7.29
%
NT Heritage Fund
4.29
%
NT International Growth Fund
5.35
%
NT International Small-Mid Cap Fund
1.77
%
NT International Value Fund
3.70
%
NT Large Company Value Fund
9.92
%
NT Mid Cap Value Fund
6.12
%
NT Non-U.S. Intrinsic Value Fund
2.08
%
NT Small Company Fund
2.49
%
 
Fixed-Income Securities (Bond Funds)
32.50
%
 
Emerging Markets Debt Fund
2.11
%
 
Global Bond Fund
6.18
%
 
Inflation-Adjusted Bond Fund
3.63
%
 
International Bond Fund
0.65
%
 
NT Diversified Bond Fund
15.60
%
 
NT High Income Fund
3.74
%
 
Short Duration Inflation Protection Bond Fund
0.59
%
 
 
 
 
Cash Equivalents (Money Market Fund)
5.00
%
 
U.S. Government Money Market Fund
5.00
%
 
 
 
 
 
 
 
 
 
 
 
 
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 cash. 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, 45% bond funds and 10% money market 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.glidepathimagea85.gifThe 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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. 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.
•
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.
•
Real Estate Investing - 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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com. 
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 13.46% Lowest Performance Quarter (4Q 2008): -17.42%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 3.39%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | S&P Target Date To 2035  
Prospectus: rr_ProspectusTable  
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 16.09%
5 Years rr_AverageAnnualReturnYear05 9.12%
10 Years rr_AverageAnnualReturnYear10 5.31%
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.86% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.89%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.84%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 86
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 279
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 489
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,092
Annual Return 2008 rr_AnnualReturn2008 (30.58%)
Annual Return 2009 rr_AnnualReturn2009 24.31%
Annual Return 2010 rr_AnnualReturn2010 14.28%
Annual Return 2011 rr_AnnualReturn2011 0.37%
Annual Return 2012 rr_AnnualReturn2012 13.62%
Annual Return 2013 rr_AnnualReturn2013 17.92%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 3.39%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 13.46%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (17.42%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.71%
5 Years rr_AverageAnnualReturnYear05 8.89%
10 Years rr_AverageAnnualReturnYear10 5.58%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 13.71%
5 Years rr_AverageAnnualReturnYear05 7.61%
10 Years rr_AverageAnnualReturnYear10 4.67%
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: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 8.88%
5 Years rr_AverageAnnualReturnYear05 6.71%
10 Years rr_AverageAnnualReturnYear10 4.20%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.67% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.70%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.64%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 66
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 218
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 384
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 865
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.93%
5 Years rr_AverageAnnualReturnYear05 9.10%
10 Years rr_AverageAnnualReturnYear10 5.80%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.86% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.14%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 680
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 912
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,163
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,877
Label rr_AverageAnnualReturnLabel A Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 7.85% [4]
5 Years rr_AverageAnnualReturnYear05 7.34% [4]
10 Years rr_AverageAnnualReturnYear10 4.70% [4]
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004 [4]
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.86% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.89%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.84%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 187
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 590
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,017
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,205
Label rr_AverageAnnualReturnLabel C Class2 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 13.61% [5]
5 Years rr_AverageAnnualReturnYear05 7.81% [5]
10 Years rr_AverageAnnualReturnYear10 4.53% [5]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [5]
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.86% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.39%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.05%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.34%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 137
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 436
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 757
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,663
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.13%
5 Years rr_AverageAnnualReturnYear05 8.36%
10 Years rr_AverageAnnualReturnYear10 5.06%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.61%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.12%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.49%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 50
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 184
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 329
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 751
Label rr_AverageAnnualReturnLabel R6 Class3 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.92% [10]
Since Inception rr_AverageAnnualReturnSinceInception 7.99% [10]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [10]
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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 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, 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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies 
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
68.75
%
NT Core Equity Plus Fund
3.07
%
NT Disciplined Growth Fund
2.61
%
NT Emerging Markets Fund
4.98
%
NT Equity Growth Fund
9.20
%
NT Global Real Estate Fund
2.06
%
NT Growth Fund
7.83
%
NT Heritage Fund
5.37
%
NT International Growth Fund
5.68
%
NT International Small-Mid Cap Fund
2.15
%
NT International Value Fund
3.50
%
NT Large Company Value Fund
10.44
%
NT Mid Cap Value Fund
6.59
%
NT Non-U.S. Intrinsic Value Fund
2.59
%
NT Small Company Fund
2.68
%
 
Fixed-Income Securities (Bond Funds)
26.75
%
 
Emerging Markets Debt Fund
2.01
%
 
Global Bond Fund
5.35
%
 
Inflation-Adjusted Bond Fund
2.68
%
 
International Bond Fund
0.00
%
 
NT Diversified Bond Fund
13.37
%
 
NT High Income Fund
3.34
%
 
Short Duration Inflation Protection Bond Fund
0.00
%
 
 
 

 
Cash Equivalents (Money Market Fund)
4.50
%
 
U.S. Government Money Market Fund
4.50
%
 
 
 
 
 
 
 
 
 
 
 
 
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 cash. 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, 45% bond funds and 10% money market 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.
glidepathimagea85.gif
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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. 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.
•
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.
•
Real Estate Investing - 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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com. 
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown. 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading 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 2009): 14.38% Lowest Performance Quarter (3Q 2011): -12.68%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 3.95%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | S&P Target Date To 2040  
Prospectus: rr_ProspectusTable  
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 17.72%
5 Years rr_AverageAnnualReturnYear05 9.81%
Since Inception rr_AverageAnnualReturnSinceInception 5.99%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.89% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 88
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 288
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 504
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,126
Annual Return 2009 rr_AnnualReturn2009 25.95%
Annual Return 2010 rr_AnnualReturn2010 14.99%
Annual Return 2011 rr_AnnualReturn2011 (0.27%)
Annual Return 2012 rr_AnnualReturn2012 14.50%
Annual Return 2013 rr_AnnualReturn2013 19.69%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 3.95%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 14.38%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.68%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.07%
5 Years rr_AverageAnnualReturnYear05 9.60%
Since Inception rr_AverageAnnualReturnSinceInception 6.47%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 15.07%
5 Years rr_AverageAnnualReturnYear05 8.38%
Since Inception rr_AverageAnnualReturnSinceInception 5.65%
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: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 9.68%
5 Years rr_AverageAnnualReturnYear05 7.30%
Since Inception rr_AverageAnnualReturnSinceInception 4.99%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.70% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.07%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.66%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 68
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 227
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 400
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 900
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.31%
5 Years rr_AverageAnnualReturnYear05 9.82%
Since Inception rr_AverageAnnualReturnSinceInception 6.68%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.89% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.11%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 682
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 920
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,177
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,908
Label rr_AverageAnnualReturnLabel A Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 9.15% [4]
5 Years rr_AverageAnnualReturnYear05 8.04% [4]
Since Inception rr_AverageAnnualReturnSinceInception 5.55% [4]
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008 [4]
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.89% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.86%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 189
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 598
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,032
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,236
Label rr_AverageAnnualReturnLabel C Class2 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.88% [5]
5 Years rr_AverageAnnualReturnYear05 8.51% [5]
Since Inception rr_AverageAnnualReturnSinceInception 5.40% [5]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [5]
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.89% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.36%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 139
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 444
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 771
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,696
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.49%
5 Years rr_AverageAnnualReturnYear05 9.05%
Since Inception rr_AverageAnnualReturnSinceInception 5.94%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.61% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.13%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.51%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 52
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 192
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 344
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 787
Label rr_AverageAnnualReturnLabel R6 Class3 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.29% [11]
Since Inception rr_AverageAnnualReturnSinceInception 8.57% [11]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [11]
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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 16% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 16.00%
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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
75.00
%
NT Core Equity Plus Fund
3.34
%
NT Disciplined Growth Fund
2.85
%
NT Emerging Markets Fund
5.44
%
NT Equity Growth Fund
10.03
%
NT Global Real Estate Fund
2.25
%
NT Growth Fund
8.54
%
NT Heritage Fund
5.86
%
NT International Growth Fund
6.20
%
NT International Small-Mid Cap Fund
2.34
%
NT International Value Fund
3.50
%
NT Large Company Value Fund
11.38
%
NT Mid Cap Value Fund
7.19
%
NT Non-U.S. Intrinsic Value Fund
3.15
%
NT Small Company Fund
2.93
%
 
Fixed-Income Securities (Bond Funds)
23.00
%
 
Emerging Markets Debt Fund
1.73
%
 
Global Bond Fund
4.60
%
 
Inflation-Adjusted Bond Fund
2.30
%
 
International Bond Fund
0.00
%
 
NT Diversified Bond Fund
11.49
%
 
NT High Income Fund
2.88
%
 
Short Duration Inflation Protection Bond Fund
0.00
%
 
 
 
 
Cash Equivalents (Money Market Fund)
2.00
%
 
U.S. Government Money Market Fund
2.00
%
 
 
 
 
 
 
 
 
 
 
 
 
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 cash. 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, 45% bond funds and 10% money market 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.
glidepathimagea85.gif
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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. 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.
•
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.
•
Real Estate Investing - 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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading 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 2009): 14.89% Lowest Performance Quarter (4Q 2008): -19.49%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 4.25%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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.
10 Years rr_AverageAnnualReturnYear10 5.66%
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | S&P Target Date To 2045  
Prospectus: rr_ProspectusTable  
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 18.46%
5 Years rr_AverageAnnualReturnYear05 10.27%
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.95%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.89%
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 2008 rr_AnnualReturn2008 (33.64%)
Annual Return 2009 rr_AnnualReturn2009 26.36%
Annual Return 2010 rr_AnnualReturn2010 15.50%
Annual Return 2011 rr_AnnualReturn2011 (0.78%)
Annual Return 2012 rr_AnnualReturn2012 15.00%
Annual Return 2013 rr_AnnualReturn2013 21.08%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 4.25%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 14.89%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.49%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.51%
5 Years rr_AverageAnnualReturnYear05 10.25%
10 Years rr_AverageAnnualReturnYear10 6.05%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 16.48%
5 Years rr_AverageAnnualReturnYear05 8.92%
10 Years rr_AverageAnnualReturnYear10 5.15%
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: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 10.56%
5 Years rr_AverageAnnualReturnYear05 7.83%
10 Years rr_AverageAnnualReturnYear10 4.62%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.72% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.75%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.69%
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 17.73%
5 Years rr_AverageAnnualReturnYear05 10.47%
10 Years rr_AverageAnnualReturnYear10 6.26%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.20%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.14%
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 Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 10.49% [4]
5 Years rr_AverageAnnualReturnYear05 8.69% [4]
10 Years rr_AverageAnnualReturnYear10 5.17% [4]
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004 [4]
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.95%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.89%
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 $ 2,267
Label rr_AverageAnnualReturnLabel C Class2 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 16.35% [5]
5 Years rr_AverageAnnualReturnYear05 9.16% [5]
10 Years rr_AverageAnnualReturnYear10 5.00% [5]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [5]
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.92% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.02%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.45%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.39%
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 16.91%
5 Years rr_AverageAnnualReturnYear05 9.71%
10 Years rr_AverageAnnualReturnYear10 5.52%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2004
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.63% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
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 (0.12%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.54%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 55
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 199
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 356
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 812
Label rr_AverageAnnualReturnLabel R6 Class3 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.85% [12]
Since Inception rr_AverageAnnualReturnSinceInception 9.15% [12]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [12]
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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 21% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 21.00%
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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
80.50
%
NT Core Equity Plus Fund
3.59
%
NT Disciplined Growth Fund
3.06
%
NT Emerging Markets Fund
5.84
%
NT Equity Growth Fund
10.77
%
NT Global Real Estate Fund
2.41
%
NT Growth Fund
9.17
%
NT Heritage Fund
6.29
%
NT International Growth Fund
6.65
%
NT International Small-Mid Cap Fund
2.51
%
NT International Value Fund
3.50
%
NT Large Company Value Fund
12.22
%
NT Mid Cap Value Fund
7.72
%
NT Non-U.S. Intrinsic Value Fund
3.63
%
NT Small Company Fund
3.14
%
 
Fixed-Income Securities (Bond Funds)
19.50
%
 
Emerging Markets Debt Fund
1.46
%
 
Global Bond Fund
3.90
%
 
Inflation-Adjusted Bond Fund
1.95
%
 
International Bond Fund
0.00
%
 
NT Diversified Bond Fund
9.75
%
 
NT High Income Fund
2.44
%
 
Short Duration Inflation Protection Bond Fund
0.00
%
 
 
 
 
Cash Equivalents (Money Market Fund)
0.00
%
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 cash. 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, 45% bond funds and 10% money market 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.
glidepathimagea85.gif
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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. 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.
•
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.
•
Real Estate Investing - 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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading 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 2009): 15.07% Lowest Performance Quarter (3Q 2011): -14.04%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 4.42%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | S&P Target Date To 2050  
Prospectus: rr_ProspectusTable  
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 19.06%
5 Years rr_AverageAnnualReturnYear05 10.68%
Since Inception rr_AverageAnnualReturnSinceInception 6.38%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.98%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 307
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 536
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,196
Annual Return 2009 rr_AnnualReturn2009 26.66%
Annual Return 2010 rr_AnnualReturn2010 15.70%
Annual Return 2011 rr_AnnualReturn2011 (0.96%)
Annual Return 2012 rr_AnnualReturn2012 15.39%
Annual Return 2013 rr_AnnualReturn2013 21.58%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 4.42%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.07%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.04%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 18.59%
5 Years rr_AverageAnnualReturnYear05 10.59%
Since Inception rr_AverageAnnualReturnSinceInception 6.67%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 17.64%
5 Years rr_AverageAnnualReturnYear05 9.37%
Since Inception rr_AverageAnnualReturnSinceInception 5.88%
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: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 11.11%
5 Years rr_AverageAnnualReturnYear05 8.13%
Since Inception rr_AverageAnnualReturnSinceInception 5.17%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.74% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.78%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.72%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 74
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 244
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 428
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 961
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 18.81%
5 Years rr_AverageAnnualReturnYear05 10.83%
Since Inception rr_AverageAnnualReturnSinceInception 6.88%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.23%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.17%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 688
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 938
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,207
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,973
Label rr_AverageAnnualReturnLabel A Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.45% [4]
5 Years rr_AverageAnnualReturnYear05 9.00% [4]
Since Inception rr_AverageAnnualReturnSinceInception 5.74% [4]
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008 [4]
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.98%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 195
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 617
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,063
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,298
Label rr_AverageAnnualReturnLabel C Class2 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.33% [5]
5 Years rr_AverageAnnualReturnYear05 9.49% [5]
Since Inception rr_AverageAnnualReturnSinceInception 5.60% [5]
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 01, 2010 [5]
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.94% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.48%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.06%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.42%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 145
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 463
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 803
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,762
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.90%
5 Years rr_AverageAnnualReturnYear05 10.04%
Since Inception rr_AverageAnnualReturnSinceInception 6.13%
Inception Date rr_AverageAnnualReturnInceptionDate May 30, 2008
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.64% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.68%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.57%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 58
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 207
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 368
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 837
Label rr_AverageAnnualReturnLabel R6 Class3 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 18.93% [13]
Since Inception rr_AverageAnnualReturnSinceInception 9.43% [13]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [13]
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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 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, 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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
83.00
%
NT Core Equity Plus Fund
3.70
%
NT Disciplined Growth Fund
3.15
%
NT Emerging Markets Fund
6.02
%
NT Equity Growth Fund
11.10
%
NT Global Real Estate Fund
2.49
%
NT Growth Fund
9.45
%
NT Heritage Fund
6.48
%
NT International Growth Fund
6.86
%
NT International Small-Mid Cap Fund
2.59
%
NT International Value Fund
3.50
%
NT Large Company Value Fund
12.60
%
NT Mid Cap Value Fund
7.96
%
NT Non-U.S. Intrinsic Value Fund
3.86
%
NT Small Company Fund
3.24
%
 
Fixed-Income Securities (Bond Funds)
17.00
%
 
Emerging Markets Debt Fund
1.28
%
 
Global Bond Fund
3.40
%
 
Inflation-Adjusted Bond Fund
1.70
%
 
International Bond Fund
0.00
%
 
NT Diversified Bond Fund
8.49
%
 
NT High Income Fund
2.13
%
 
Short Duration Inflation Protection Bond Fund
0.00
%
 
 
 
 
Cash Equivalents (Money Market Fund)
0.00
%
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 cash. 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, 45% bond funds and 10% money market 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.
glidepathimagea85.gif
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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. 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.
•
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.
•
Real Estate Investing - 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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (1Q 2012): 11.54% Lowest Performance Quarter (3Q 2015): -7.42%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 4.46%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | S&P Target Date To 2055 Plus Index  
Prospectus: rr_ProspectusTable  
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 19.48%
5 Years rr_AverageAnnualReturnYear05 11.00%
Since Inception rr_AverageAnnualReturnSinceInception 9.09%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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 0.95% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.99%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 309
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 541
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,207
Annual Return 2012 rr_AnnualReturn2012 15.51%
Annual Return 2013 rr_AnnualReturn2013 22.21%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 4.46%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.54%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (7.42%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 19.04%
5 Years rr_AverageAnnualReturnYear05 10.86%
Since Inception rr_AverageAnnualReturnSinceInception 9.35%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 18.23%
5 Years rr_AverageAnnualReturnYear05 9.85%
Since Inception rr_AverageAnnualReturnSinceInception 8.52%
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: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 11.33%
5 Years rr_AverageAnnualReturnYear05 8.39%
Since Inception rr_AverageAnnualReturnSinceInception 7.30%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
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 0.75% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.79%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.72%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 74
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 246
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 432
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 972
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 19.28%
5 Years rr_AverageAnnualReturnYear05 11.11%
Since Inception rr_AverageAnnualReturnSinceInception 9.57%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
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 [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.95% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.24%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.17%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 688
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 940
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,211
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,982
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.93%
5 Years rr_AverageAnnualReturnYear05 9.29%
Since Inception rr_AverageAnnualReturnSinceInception 8.12%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
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 0.95% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.99%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 195
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 619
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,067
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,308
Label rr_AverageAnnualReturnLabel C Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 17.87%
5 Years rr_AverageAnnualReturnYear05 9.76%
Since Inception rr_AverageAnnualReturnSinceInception 8.26%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
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 0.95% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.49%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.42%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 145
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 465
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 807
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,772
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 18.44%
5 Years rr_AverageAnnualReturnYear05 10.32%
Since Inception rr_AverageAnnualReturnSinceInception 8.81%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2011
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
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 0.65% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.69%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.12%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.57%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 58
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 209
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 373
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 848
Label rr_AverageAnnualReturnLabel R6 Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 19.36% [14]
Since Inception rr_AverageAnnualReturnSinceInception 9.67% [14]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [14]
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 67 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) [1]
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination November 30, 2019
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 other than transaction costs associated with purchasing futures. 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 12% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 12.00%
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. You may be required to pay brokerage commissions on your purchases of Investor or I Class shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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). 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
85.00
%
NT Core Equity Plus Fund
3.79
%
NT Disciplined Growth Fund
3.23
%
NT Emerging Markets Fund
6.16
%
NT Equity Growth Fund
11.37
%
NT Global Real Estate Fund
2.55
%
NT Growth Fund
9.68
%
NT Heritage Fund
6.64
%
NT International Growth Fund
7.02
%
NT International Small-Mid Cap Fund
2.65
%
NT International Value Fund
3.50
%
NT Large Company Value Fund
12.91
%
NT Mid Cap Value Fund
8.15
%
NT Non-U.S. Intrinsic Value Fund
4.03
%
NT Small Company Fund
3.32
%
 
Fixed-Income Securities (Bond Funds)
15.00
%
 
Emerging Markets Debt Fund
1.13
%
 
Global Bond Fund
3.00
%
 
Inflation-Adjusted Bond Fund
1.50
%
 
International Bond Fund
0.00
%
 
NT Diversified Bond Fund
7.49
%
 
NT High Income Fund
1.88
%
 
Short Duration Inflation Protection Bond Fund
0.00
%
 
 
 
 
Cash Equivalents (Money Market Fund)
0.00
%
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 cash. 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, 45% bond funds and 10% money market 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.
glidepathimagea85.gif
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. In order to implement such deviations, the fund may purchase futures directly. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
“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.
•
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.
•
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.
•
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.
•
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. 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.
•
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.
•
Real Estate Investing - 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.
•
Tobacco Exclusion – The underlying funds do not invest in securities issued by companies assigned the Global Industry Classification Standard (GICS) or the Bloomberg Industry Classification Standard (BICS) for the tobacco industry. This exclusion may cause an underlying fund to forego profitable investment opportunities.
•
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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund, including losses near to, at, or after retirement. There is no guarantee that the fund will provide adequate income at or through your retirement.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.  
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.  
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (1Q 2017): 5.75% Lowest Performance Quarter (1Q 2016): 0.49%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 4.53%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Market Index Changed rr_PerformanceTableMarketIndexChanged Effective January 1, 2018, the fund's investment advisor has selected a different index for comparison purposes. The advisor believes the S&P Target Date To 2060+ Index is more reflective of the fund's strategy. The fund's investment process did not change.
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 | S&P Target Date To 2055 Plus Index  
Prospectus: rr_ProspectusTable  
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 19.48%
Since Inception rr_AverageAnnualReturnSinceInception 14.84%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | S&P Target Date To 2060 Plus  
Prospectus: rr_ProspectusTable  
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+ Index2 (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 20.02% [15]
Since Inception rr_AverageAnnualReturnSinceInception 15.22% [15]
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015 [15]
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee $ 25
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.96% [1]
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 1.00%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.08%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 94
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 311
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 545
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,217
Annual Return 2016 rr_AnnualReturn2016 7.71%
Annual Return 2017 rr_AnnualReturn2017 19.31%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 4.53%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2017
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 5.75%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2016
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn 0.49%
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 19.31%
Since Inception rr_AverageAnnualReturnSinceInception 13.65%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 18.63%
Since Inception rr_AverageAnnualReturnSinceInception 13.05%
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: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 11.34%
Since Inception rr_AverageAnnualReturnSinceInception 10.46%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | I CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.76% [1]
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 0.80%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.08%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.72%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 74
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 248
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 437
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 983
Label rr_AverageAnnualReturnLabel I Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 19.54%
Since Inception rr_AverageAnnualReturnSinceInception 13.88%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | A CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none [3]
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.96% [1]
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 1.25%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.08%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.17%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 688
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 942
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,215
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,992
Label rr_AverageAnnualReturnLabel A Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 12.15%
Since Inception rr_AverageAnnualReturnSinceInception 10.43%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | C CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther 1.00%
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.96% [1]
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 0.04%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 2.00%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.08%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.92%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 195
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 621
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,071
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,318
Label rr_AverageAnnualReturnLabel C Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 18.11%
Since Inception rr_AverageAnnualReturnSinceInception 12.55%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | R CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.96% [1]
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 1.50%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.08%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 1.42%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 145
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 467
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 812
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,782
Label rr_AverageAnnualReturnLabel R Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 18.68%
Since Inception rr_AverageAnnualReturnSinceInception 13.07%
Inception Date rr_AverageAnnualReturnInceptionDate Sep. 30, 2015
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO | R6 CLASS  
Prospectus: rr_ProspectusTable  
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) rr_MaximumDeferredSalesChargeOverOther none
Maximum Account Fee rr_MaximumAccountFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.65% [1]
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 0.69%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.12%) [2]
Net Expenses (as a percentage of Assets) rr_NetExpensesOverAssets 0.57%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 58
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 209
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 373
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 848
Label rr_AverageAnnualReturnLabel R6 Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 19.71% [16]
Since Inception rr_AverageAnnualReturnSinceInception 13.98% [16]
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 23, 2017 [16]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
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. You may be required to pay brokerage commissions on your purchases of Investor shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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 cash equivalents, 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.

Equity Securities (Stock Funds)
25.00
%
 
Fixed-Income Securities (Bond Funds)
69.00
%
Core Equity Plus Fund
1.50
%
 
Diversified Bond Fund
20.50
%
Equity Growth Fund
5.00
%
 
Emerging Markets Debt Fund
1.50
%
Growth Fund
2.75
%
 
Global Bond Fund
8.00
%
Heritage Fund
1.25
%
 
Inflation-Adjusted Bond Fund
10.00
%
Large Company Value Fund
6.75
%
 
International Bond Fund
7.00
%
Mid Cap Value Fund
4.25
%
 
NT High Income Fund
2.00
%
NT Disciplined Growth Fund
1.00
%
 
Short Duration Fund
7.00
%
Real Estate Fund
1.50
%
 
Short Duration Inflation Protection Bond Fund
13.00
%
Small Company Fund
1.00
%
 
 
 
 
 
 
Cash Equivalents (Money Market Funds)
6.00
%
 
 
 
U.S. Government Money Market Fund
6.00
%
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)
Cash Equivalents (Money Market Funds)
Operating Ranges
20-30%
55-75%
3-25%
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
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.
•
“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.
•
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.
•
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.
•
Foreign 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. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. 
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. 
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance 
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 6.20% Lowest Performance Quarter (4Q 2008): -3.97%
As of September 30, 2018 the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 1.15%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | Russell 3000 Index  
Prospectus: rr_ProspectusTable  
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 21.13%
5 Years rr_AverageAnnualReturnYear05 15.57%
10 Years rr_AverageAnnualReturnYear10 8.59%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | Bloomberg Barclays U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg Barclays U.S. Aggregate Bond Index    (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 3.54%
5 Years rr_AverageAnnualReturnYear05 2.10%
10 Years rr_AverageAnnualReturnYear10 4.00%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.70%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.71%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 73
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 227
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 396
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 883
Annual Return 2008 rr_AnnualReturn2008 (6.66%)
Annual Return 2009 rr_AnnualReturn2009 10.59%
Annual Return 2010 rr_AnnualReturn2010 6.84%
Annual Return 2011 rr_AnnualReturn2011 4.88%
Annual Return 2012 rr_AnnualReturn2012 6.78%
Annual Return 2013 rr_AnnualReturn2013 4.27%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 1.15%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 6.20%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.97%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 6.46%
5 Years rr_AverageAnnualReturnYear05 4.11%
10 Years rr_AverageAnnualReturnYear10 4.21%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 5.37%
5 Years rr_AverageAnnualReturnYear05 3.14%
10 Years rr_AverageAnnualReturnYear10 3.29%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 3.96%
5 Years rr_AverageAnnualReturnYear05 2.87%
10 Years rr_AverageAnnualReturnYear10 3.00%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY CONSERVATIVE | R CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.70%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.21%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 124
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 385
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 666
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,465
Label rr_AverageAnnualReturnLabel R Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 5.92% [17]
5 Years rr_AverageAnnualReturnYear05 3.59% [17]
10 Years rr_AverageAnnualReturnYear10 3.69% [17]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
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. You may be required to pay brokerage commissions on your purchases of Investor shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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 cash equivalents, 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
45.00
%
 
Fixed-Income Securities (Bond Funds)
49.00
%
Core Equity Plus Fund
2.25
%
 
Diversified Bond Fund
20.50
%
Equity Growth Fund
7.25
%
 
Emerging Markets Debt Fund
2.00
%
Growth Fund
5.00
%
 
Global Bond Fund
7.00
%
Heritage Fund
2.75
%
 
Inflation-Adjusted Bond Fund
7.00
%
International Growth Fund
4.50
%
 
International Bond Fund
5.50
%
Large Company Value Fund
7.25
%
 
NT High Income Fund
2.00
%
Mid Cap Value Fund
5.50
%
 
Short Duration Inflation Protection Bond Fund
5.00
%
NT Disciplined Growth Fund
1.50
%
 
 
 
NT Global Real Estate Fund
1.50
%
 
Cash Equivalents (Money Market Funds)
6.00
%
NT International Small-Mid Cap Fund
1.00
%
 
U.S. Government Money Market Fund
6.00
%
NT International Value Fund
5.00
%
 
 
 
Small Company Fund
1.50
%
 
 
 
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)
Cash Equivalents (Money Market Funds)
Operating Ranges
39-51%
38-55%
2-20%
Risk [Heading] rr_RiskHeading Principal Risks 
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
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.
•
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.
•
“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.
•
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.
•
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. 
•
Foreign 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. Fluctuations in currency exchange rates also may affect an underlying fund’s share price.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com. 
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown. 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown. 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 9.27% Lowest Performance Quarter (4Q 2008): -8.82%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 2.08%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | Russell 3000 Index  
Prospectus: rr_ProspectusTable  
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 21.13%
5 Years rr_AverageAnnualReturnYear05 15.57%
10 Years rr_AverageAnnualReturnYear10 8.59%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | Bloomberg Barclays U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg Barclays U.S. Aggregate Bond Index    (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 3.54%
5 Years rr_AverageAnnualReturnYear05 2.10%
10 Years rr_AverageAnnualReturnYear10 4.00%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.80%
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 2008 rr_AnnualReturn2008 (16.03%)
Annual Return 2009 rr_AnnualReturn2009 15.81%
Annual Return 2010 rr_AnnualReturn2010 9.86%
Annual Return 2011 rr_AnnualReturn2011 3.76%
Annual Return 2012 rr_AnnualReturn2012 10.05%
Annual Return 2013 rr_AnnualReturn2013 10.31%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 2.08%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.27%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (8.82%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 11.09%
5 Years rr_AverageAnnualReturnYear05 6.36%
10 Years rr_AverageAnnualReturnYear10 5.20%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 10.02%
5 Years rr_AverageAnnualReturnYear05 5.27%
10 Years rr_AverageAnnualReturnYear10 4.24%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 6.69%
5 Years rr_AverageAnnualReturnYear05 4.68%
10 Years rr_AverageAnnualReturnYear10 3.82%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: CONSERVATIVE | R CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.80%
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
1 Year rr_AverageAnnualReturnYear01 10.61% [17]
5 Years rr_AverageAnnualReturnYear05 5.84% [17]
10 Years rr_AverageAnnualReturnYear10 4.68% [17]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
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. You may be required to pay brokerage commissions on your purchases of Investor shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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 cash equivalents.
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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
64.00
%
 
Fixed-Income Securities (Bond Funds)
32.00
%
Core Equity Plus Fund
3.25
%
 
Diversified Bond Fund
14.50
%
Emerging Markets Fund
4.00
%
 
Emerging Markets Debt Fund
2.00
%
Equity Growth Fund
9.75
%
 
Global Bond Fund
5.00
%
Growth Fund
6.50
%
 
Inflation-Adjusted Bond Fund
5.00
%
Heritage Fund
5.00
%
 
International Bond Fund
2.00
%
International Growth Fund
6.00
%
 
NT High Income Fund
2.50
%
Large Company Value Fund
8.50
%
 
Short Duration Inflation Protection Bond Fund
1.00
%
Mid Cap Value Fund
6.00
%
 
 
 
NT Disciplined Growth Fund
2.00
%
 
Cash Equivalents (Money Market Funds)
4.00
%
NT Global Real Estate Fund
2.00
%
 
U.S. Government Money Market Fund
4.00
%
NT International Small-Mid Cap Fund
2.00
%
 
 
 
NT International Value Fund
4.00
%
 
 
 
NT Non-U.S. Intrinsic Value Fund
2.50
%
 
 
 
Small Company Fund
2.50
%
 
 
 
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)
Cash Equivalents (Money Market Funds)
Operating Ranges
53-73%
21-41%
0-15%
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
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.
•
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.
•
“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.
•
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.
•
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.
•
Foreign 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. 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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 11.86% Lowest Performance Quarter (4Q 2008): -14.20%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 3.14%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | Russell 3000 Index  
Prospectus: rr_ProspectusTable  
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 21.13%
5 Years rr_AverageAnnualReturnYear05 15.57%
10 Years rr_AverageAnnualReturnYear10 8.59%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | Bloomberg Barclays U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg Barclays U.S. Aggregate Bond Index    (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 3.54%
5 Years rr_AverageAnnualReturnYear05 2.10%
10 Years rr_AverageAnnualReturnYear10 4.00%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.89%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.90%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 92
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 287
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 499
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,108
Annual Return 2008 rr_AnnualReturn2008 (25.92%)
Annual Return 2009 rr_AnnualReturn2009 21.76%
Annual Return 2010 rr_AnnualReturn2010 12.74%
Annual Return 2011 rr_AnnualReturn2011 0.88%
Annual Return 2012 rr_AnnualReturn2012 13.23%
Annual Return 2013 rr_AnnualReturn2013 16.04%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 3.14%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.86%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.20%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 15.43%
5 Years rr_AverageAnnualReturnYear05 8.46%
10 Years rr_AverageAnnualReturnYear10 5.72%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 14.36%
5 Years rr_AverageAnnualReturnYear05 7.33%
10 Years rr_AverageAnnualReturnYear10 4.79%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 9.20%
5 Years rr_AverageAnnualReturnYear05 6.37%
10 Years rr_AverageAnnualReturnYear10 4.28%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: MODERATE | R CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.89%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.40%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 143
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 444
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 767
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,679
Label rr_AverageAnnualReturnLabel R Class 1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 14.85% [17]
5 Years rr_AverageAnnualReturnYear05 7.92% [17]
10 Years rr_AverageAnnualReturnYear10 5.19% [17]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund. 
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
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. You may be required to pay brokerage commissions on your purchases of Investor shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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 cash equivalents.
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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
79.00
%
 
Fixed-Income Securities (Bond Funds)
20.00
%
Core Equity Plus Fund
3.50
%
 
Diversified Bond Fund
7.00
%
Emerging Markets Fund
5.50
%
 
Emerging Markets Debt Fund
1.50
%
Equity Growth Fund
10.50
%
 
Global Bond Fund
3.00
%
Growth Fund
8.75
%
 
Inflation-Adjusted Bond Fund
3.00
%
Heritage Fund
7.00
%
 
NT High Income Fund
4.50
%
International Growth Fund
7.00
%
 
Short Duration Inflation Protection Bond Fund
1.00
%
Large Company Value Fund
11.50
%
 
 
 
Mid Cap Value Fund
7.00
%
 
Cash Equivalents (Money Market Funds)
1.00
%
NT Disciplined Growth Fund
2.75
%
 
U.S. Government Money Market Fund
1.00
%
NT Global Real Estate Fund
2.50
%
 
 
 
NT International Small-Mid Cap Fund
2.50
%
 
 
 
NT International Value Fund
3.75
%
 
 
 
NT Non-U.S. Intrinsic Value Fund
3.75
%
 
 
 
Small Company Fund
3.00
%
 
 
 
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)
Cash Equivalents (Money Market Funds)
Operating Ranges
60-90%
10-30%
0-15%
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
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.
•
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.
•
“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.
•
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.
•
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.
•
Foreign 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. 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.
•
Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 13.90% Lowest Performance Quarter (4Q 2008): -18.80%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 4.14%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | Russell 3000 Index  
Prospectus: rr_ProspectusTable  
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 21.13%
5 Years rr_AverageAnnualReturnYear05 15.57%
10 Years rr_AverageAnnualReturnYear10 8.59%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | Bloomberg Barclays U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg Barclays U.S. Aggregate Bond Index    (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 3.54%
5 Years rr_AverageAnnualReturnYear05 2.10%
10 Years rr_AverageAnnualReturnYear10 4.00%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.96%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.97%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 99
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 310
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 537
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,190
Annual Return 2008 rr_AnnualReturn2008 (33.87%)
Annual Return 2009 rr_AnnualReturn2009 26.68%
Annual Return 2010 rr_AnnualReturn2010 15.59%
Annual Return 2011 rr_AnnualReturn2011 (1.68%)
Annual Return 2012 rr_AnnualReturn2012 15.42%
Annual Return 2013 rr_AnnualReturn2013 20.60%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 4.14%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 13.90%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (18.80%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 19.13%
5 Years rr_AverageAnnualReturnYear05 10.22%
10 Years rr_AverageAnnualReturnYear10 5.98%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 18.02%
5 Years rr_AverageAnnualReturnYear05 8.80%
10 Years rr_AverageAnnualReturnYear10 4.97%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 11.40%
5 Years rr_AverageAnnualReturnYear05 7.75%
10 Years rr_AverageAnnualReturnYear10 4.49%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: AGGRESSIVE | R CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.96%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.47%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 150
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 466
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 803
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,756
Label rr_AverageAnnualReturnLabel R Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 18.59% [17]
5 Years rr_AverageAnnualReturnYear05 9.67% [17]
10 Years rr_AverageAnnualReturnYear10 5.45% [17]
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE  
Prospectus: rr_ProspectusTable  
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 and hold shares of the fund.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
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. You may be required to pay brokerage commissions on your purchases of Investor shares of the fund, which are not reflected in the example.  Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
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 cash equivalent 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. The table also shows the neutral weightings of each underlying fund currently being used within the various asset classes. This information is as of the date of this prospectus.
Equity Securities (Stock Funds)
100.00
%
Core Equity Plus Fund
3.75
%
Emerging Markets Fund
8.50
%
Equity Growth Fund
11.25
%
Growth Fund
11.25
%
Heritage Fund
8.50
%
International Growth Fund
10.00
%
Large Company Value Fund
12.00
%
Mid Cap Value Fund
8.00
%
NT Disciplined Growth Fund
3.75
%
NT Global Real Estate Fund
3.00
%
NT International Small-Mid Cap Fund
5.00
%
NT International Value Fund
4.00
%
NT Non-U.S. Intrinsic Value Fund
6.00
%
Small Company Fund
5.00
%
 
Fixed-Income Securities (Bond Funds)
0.00
%
 
 
 
 
Cash Equivalents (Money Market Funds)
0.00
%
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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)
Cash Equivalents (Money Market Funds)
Operating Ranges
75-100%
0-10%
0-15%
Risk [Heading] rr_RiskHeading Principal Risks 
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
•
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.
•
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.
•
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.
•
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.
•
“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.
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Foreign 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. 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.
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Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Risk Lose Money [Text] rr_RiskLoseMoney Principal Loss – At any given time your shares may be worth less than the price you paid for them. In other words, it is possible to lose money by investing in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the fund is not a bank deposit, and it is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Fund Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance. The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the fund. The bar chart shows changes in the fund’s performance from year to year for Investor Class shares. The table shows how the fund’s average annual returns for the periods shown compared with those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads Sales charges and account fees, if applicable, are not reflected in the bar chart. If those charges were included, returns would be less than those shown.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (3Q 2009): 15.67% Lowest Performance Quarter (4Q 2008): -22.24%
As of September 30, 2018, the most recent calendar quarter end, the fund’s Investor Class year-to-date return was 5.36%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2017
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as 401(k) plans or IRAs.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown 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 | Russell 3000 Index  
Prospectus: rr_ProspectusTable  
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 21.13%
5 Years rr_AverageAnnualReturnYear05 15.57%
10 Years rr_AverageAnnualReturnYear10 8.59%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | Bloomberg Barclays U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
Label rr_AverageAnnualReturnLabel Bloomberg Barclays U.S. Aggregate Bond Index    (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 3.54%
5 Years rr_AverageAnnualReturnYear05 2.10%
10 Years rr_AverageAnnualReturnYear10 4.00%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | INVESTOR CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 1.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.04%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 106
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 331
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 575
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,271
Annual Return 2008 rr_AnnualReturn2008 (39.69%)
Annual Return 2009 rr_AnnualReturn2009 28.59%
Annual Return 2010 rr_AnnualReturn2010 16.70%
Annual Return 2011 rr_AnnualReturn2011 (3.78%)
Annual Return 2012 rr_AnnualReturn2012 16.79%
Annual Return 2013 rr_AnnualReturn2013 25.94%
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%
Year to Date Return, Label rr_YearToDateReturnLabel Investor Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2018
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 5.36%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.67%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.24%)
Label rr_AverageAnnualReturnLabel Investor Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 22.78%
5 Years rr_AverageAnnualReturnYear05 12.08%
10 Years rr_AverageAnnualReturnYear10 6.05%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | INVESTOR CLASS | After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions
1 Year rr_AverageAnnualReturnYear01 21.68%
5 Years rr_AverageAnnualReturnYear05 10.70%
10 Years rr_AverageAnnualReturnYear10 5.19%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | INVESTOR CLASS | After Taxes on Distributions and Sales  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel Return After Taxes on Distributions and Sale of Fund Shares
1 Year rr_AverageAnnualReturnYear01 13.64%
5 Years rr_AverageAnnualReturnYear05 9.38%
10 Years rr_AverageAnnualReturnYear10 4.67%
American Century Asset Allocation Portfolio | ONE CHOICE PORTFOLIO: VERY AGGRESSIVE | R CLASS  
Prospectus: rr_ProspectusTable  
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 0.01%
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 1.03%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.54%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 157
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 487
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 840
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,833
Label rr_AverageAnnualReturnLabel R Class1 Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 22.20% [17]
5 Years rr_AverageAnnualReturnYear05 11.53% [17]
10 Years rr_AverageAnnualReturnYear10 5.52% [17]
[1] The management fee has been restated to reflect current fees.
[2] The advisor has agreed to waive a portion of the fund’s management fee. The advisor expects this waiver to continue until November 30, 2019 and cannot terminate it prior to such date without the approval of the Board of Directors.
[3] 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.
[4] Prior to March 1, 2010, the A Class was referred to as the Advisor Class and did not have a front-end sales charge. Performance prior to that date has been restated to reflect this charge.
[5] Historical performance for C Class prior to its inception is based on the performance of Investor Class shares. C Class performance has been adjusted to reflect differences in sales charges, if applicable, and expenses between classes.
[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] Historical performance for the R6 Class prior to its inception reflects the performance of the R6 Class of the One Choice 2020 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 2020 Portfolio R6 on October 20, 2017 pursuant to a reorganization.
[8] 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.
[9] 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.
[10] 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.
[11] 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.
[12] 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.
[13] 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.
[14] 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.
[15] Effective January 1, 2018, the fund's investment advisor has selected a different index for comparison purposes. The advisor believes the S&P Target Date To 2060+ Index is more reflective of the fund's strategy. The fund's investment process did not change.
[16] 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.
[17] 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.