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Label Element Value
Prospectus: rr_ProspectusTable  
Document Type dei_DocumentType 497
Document Period End Date dei_DocumentPeriodEndDate Jul. 28, 2017
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 Jul. 28, 2017
Document Effective Date dei_DocumentEffectiveDate Dec. 01, 2016
Prospectus Date rr_ProspectusDate Dec. 01, 2016
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
ARDTX
Risk/Return [Heading] rr_RiskReturnHeading One Choice In Retirement Portfolio R6
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses1 (expenses that you pay each year as a percentage of the value of your investment) [1]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.13%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 22% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 22.00%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice In Retirement Portfolio R6 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
45.00
%
NT Core Equity Plus Fund
3.00
%
NT Disciplined Growth Fund
1.50
%
NT Equity Growth Fund
10.00
%
NT Global Real Estate Fund
1.00
%
NT Growth Fund
4.50
%
NT Heritage Fund
2.25
%
NT International Growth Fund
4.50
%
NT International Value Fund
2.25
%
NT Large Company Value Fund
9.50
%
NT Mid Cap Value Fund
4.50
%
NT Small Company Fund
2.00
%
 
Fixed-Income Securities (Bond Funds)
45.00
%
 
Global Bond Fund
7.00
%
 
NT High Income Fund
3.80
%
 
Inflation-Adjusted Bond Fund
1.50
%
 
International Bond Fund
5.00
%
 
NT Diversified Bond Fund
21.60
%
 
Short Duration Inflation Protection Bond Fund
6.10
%
 
 
 

 
Cash Equivalents (Money Market Fund)
10.00
%
 
U.S. Government Money Market Fund
10.00
%
 
 
 
 
 
 
 The neutral mix of One Choice In Retirement Portfolio R6 is expected to remain fixed over time. The fund is generally intended for investors near to, at, or in retirement and who likely are no longer making new investments in the fund. The fund is designed for investors who plan to gradually withdraw the value of their account after retirement. The fund assumes a retirement age of 65 and may not be appropriate for an investor retiring at an age well before or after age 65. 
The portfolio managers regularly review the fund’s allocations to determine whether rebalancing is appropriate. In order to better balance risks in changing market environments, the portfolio managers may make modest deviations from the neutral mix in light of prevailing market conditions. We reserve the right to modify the neutral mix and underlying funds from time to time should circumstances warrant a change.
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 R6 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 is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit ipro.americancentury.com.
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 R6 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 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (2Q 2014): 3.03% Lowest Performance Quarter (3Q 2015): -3.63%
As of September 30, 2016, the most recent calendar quarter end, the fund’s R6 Class year-to-date return was 6.29%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2015
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO R6 | S&P Target Date Retirement Income Index  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel S&P Target Date Retirement Income Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 (0.18%)
Since Inception rr_AverageAnnualReturnSinceInception 3.16%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE IN RETIREMENT PORTFOLIO R6 | ONE CHOICE IN RETIREMENT PORTFOLIO R6, R6Class  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [2]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.55%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.13%) [3]
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
Annual Return 2014 rr_AnnualReturn2014 6.55%
Annual Return 2015 rr_AnnualReturn2015 (1.32%)
Year to Date Return, Label rr_YearToDateReturnLabel R6 Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2016
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.29%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.03%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (3.63%)
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 (1.32%)
Since Inception rr_AverageAnnualReturnSinceInception 4.00%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
ARBDX
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2020 Portfolio R6
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses1 (expenses that you pay each year as a percentage of the value of your investment) [4]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.13%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. 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%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2020 Portfolio R6 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
47.90
%
NT Core Equity Plus Fund
3.00
%
NT Disciplined Growth Fund
1.73
%
NT Emerging Markets Fund
0.75
%
NT Equity Growth Fund
9.75
%
NT Global Real Estate Fund
1.15
%
NT Growth Fund
5.01
%
NT Heritage Fund
2.71
%
NT International Growth Fund
4.63
%
NT International Small-Mid Cap Fund
0.19
%
NT International Value Fund
2.63
%
NT Large Company Value Fund
9.50
%
NT Mid Cap Value Fund
5.00
%
NT Small Company Fund
1.85
%
 
Fixed-Income Securities (Bond Funds)
43.60
%
 
Global Bond Fund
6.63
%
 
NT High Income Fund
3.75
%
 
Inflation-Adjusted Bond Fund
2.35
%
 
International Bond Fund
4.75
%
 
NT Diversified Bond Fund
20.97
%
 
Short Duration Inflation Protection Bond Fund
5.15
%
 
 
 
 
Cash Equivalents (Money Market Fund)
8.50
%
 
U.S. Government Money Market Fund
8.50
%
 
 
 
 
 
 
 
 
 
 
 
 
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 R6, 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.
glidepathimagea52.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. 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 R6 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 is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit ipro.americancentury.com.
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 R6 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 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (2Q 2014): 3.22% Lowest Performance Quarter (3Q 2015): -4.06%
As of September 30, 2016, the most recent calendar quarter end, the fund’s R6 Class year-to-date return was 6.41%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2015
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO R6 | S&P Target Date To 2020 Index  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel S&P Target Date To 2020 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 (0.15%)
Since Inception rr_AverageAnnualReturnSinceInception 4.00%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2020 PORTFOLIO R6 | ONE CHOICE 2020 PORTFOLIO R6, R6 Class  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.52%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [5]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.55%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.13%) [6]
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
Annual Return 2014 rr_AnnualReturn2014 7.10%
Annual Return 2015 rr_AnnualReturn2015 (1.30%)
Year to Date Return, Label rr_YearToDateReturnLabel R6 Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2016
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.41%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.22%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (4.06%)
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 (1.30%)
Since Inception rr_AverageAnnualReturnSinceInception 4.40%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
ARWDX
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2025 Portfolio R6
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses1 (expenses that you pay each year as a percentage of the value of your investment) [7]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.13%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. 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%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2025 Portfolio R6 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
52.90
%
NT Core Equity Plus Fund
3.00
%
NT Disciplined Growth Fund
2.10
%
NT Emerging Markets Fund
1.75
%
NT Equity Growth Fund
9.50
%
NT Global Real Estate Fund
1.40
%
NT Growth Fund
5.65
%
NT Heritage Fund
3.65
%
NT International Growth Fund
5.00
%
NT International Small-Mid Cap Fund
0.50
%
NT International Value Fund
3.25
%
NT Large Company Value Fund
9.75
%
NT Mid Cap Value Fund
5.75
%
NT Small Company Fund
1.60
%
 
Fixed-Income Securities (Bond Funds)
41.10
%
 
Global Bond Fund
6.00
%
 
NT High Income Fund
3.55
%
 
Inflation-Adjusted Bond Fund
3.60
%
 
International Bond Fund
4.20
%
 
NT Diversified Bond Fund
20.20
%
 
Short Duration Inflation Protection Bond Fund
3.55
%
 
 
 
 
Cash Equivalents (Money Market Fund)
6.00
%
 
U.S. Government Money Market Fund
6.00
%
 
 
 
 
 
 
 
 
 
 
 
 
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 R6, 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.  
glidepathimagea52.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. 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 R6 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 is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit ipro.americancentury.com.
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 R6 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 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (2Q 2014): 3.48% Lowest Performance Quarter (3Q 2015): -4.54%
As of September 30, 2016, the most recent calendar quarter end, the fund’s R6 Class year-to-date return was 6.62%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2015
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO R6 | S&P Target Date To 2025 Index  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel S&P Target Date To 2025 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 (0.21%)
Since Inception rr_AverageAnnualReturnSinceInception 4.30%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2025 PORTFOLIO R6 | ONE CHOICE 2025 PORTFOLIO R6, R6 CLASS  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.54%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [8]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.57%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.13%) [9]
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
Annual Return 2014 rr_AnnualReturn2014 7.42%
Annual Return 2015 rr_AnnualReturn2015 (1.18%)
Year to Date Return, Label rr_YearToDateReturnLabel R6 Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2016
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.62%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.48%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (4.54%)
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 (1.18%)
Since Inception rr_AverageAnnualReturnSinceInception 4.83%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
ARCUX
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2030 Portfolio R6
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses1 (expenses that you pay each year as a percentage of the value of your investment) [10]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.12%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. 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%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2030 Portfolio R6 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
58.60
%
NT Core Equity Plus Fund
3.00
%
NT Disciplined Growth Fund
2.48
%
NT Emerging Markets Fund
2.55
%
NT Equity Growth Fund
9.35
%
NT Global Real Estate Fund
1.65
%
NT Growth Fund
6.76
%
NT Heritage Fund
4.34
%
NT International Growth Fund
5.48
%
NT International Small-Mid Cap Fund
0.81
%
NT International Value Fund
3.88
%
NT Large Company Value Fund
10.10
%
NT Mid Cap Value Fund
6.00
%
NT Small Company Fund
2.20
%
 
Fixed-Income Securities (Bond Funds)
36.40
%
 
Global Bond Fund
5.38
%
 
NT High Income Fund
3.30
%
 
Inflation-Adjusted Bond Fund
4.60
%
 
International Bond Fund
2.80
%
 
NT Diversified Bond Fund
18.32
%
 
Short Duration Inflation Protection Bond Fund
2.00
%
 
 
 
 
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 R6, 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.
glidepathimagea52.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. 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 R6 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 is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit ipro.americancentury.com.
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 R6 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 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (2Q 2014): 3.56% Lowest Performance Quarter (3Q 2015): -5.04%
As of September 30, 2016, the most recent calendar quarter end, the fund’s R6 Class year-to-date return was 6.77%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2015
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO R6 | S&P Target Date To 2030 Index  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel S&P Target Date To 2030 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 (0.26%)
Since Inception rr_AverageAnnualReturnSinceInception 4.57%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2030 PORTFOLIO R6 | ONE CHOICE 2030 PORTFOLIO R6, R6 CLASS  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [11]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.58%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.12%) [12]
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 174
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 312
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 715
Annual Return 2014 rr_AnnualReturn2014 7.74%
Annual Return 2015 rr_AnnualReturn2015 (1.18%)
Year to Date Return, Label rr_YearToDateReturnLabel R6 Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2016
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.77%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.56%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.04%)
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 (1.18%)
Since Inception rr_AverageAnnualReturnSinceInception 5.17%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
ARLDX
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2035 Portfolio R6
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses1 (expenses that you pay each year as a percentage of the value of your investment) [13]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. 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%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2035 Portfolio R6 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) and 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
64.50
%
NT Core Equity Plus Fund
3.25
%
NT Disciplined Growth Fund
2.85
%
NT Emerging Markets Fund
3.00
%
NT Equity Growth Fund
9.25
%
NT Global Real Estate Fund
1.90
%
NT Growth Fund
8.39
%
NT Heritage Fund
4.53
%
NT International Growth Fund
6.25
%
NT International Small-Mid Cap Fund
1.13
%
NT International Value Fund
4.50
%
NT Large Company Value Fund
10.50
%
NT Mid Cap Value Fund
6.00
%
NT Small Company Fund
2.95
%
 
Fixed-Income Securities (Bond Funds)
30.50
%
 
Global Bond Fund
4.75
%
 
NT High Income Fund
3.00
%
 
Inflation-Adjusted Bond Fund
5.25
%
 
International Bond Fund
0.80
%
 
NT Diversified Bond Fund
16.05
%
 
Short Duration Inflation Protection Bond Fund
0.65
%
 
 
 
 
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 R6, 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.
glidepathimagea52.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. 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 R6 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 is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit ipro.americancentury.com.
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 R6 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 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (2Q 2014): 3.74% Lowest Performance Quarter (3Q 2015): -5.68%
As of September 30, 2016, the most recent calendar quarter end, the fund’s R6 Class year-to-date return was 6.54%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2015
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO R6 | S&P Target Date To 2035 Index  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel S&P Target Date To 2035 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 (0.46%)
Since Inception rr_AverageAnnualReturnSinceInception 4.79%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2035 PORTFOLIO R6 | ONE CHOICE 2035 PORTFOLIO R6, R6 CLASS  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.57%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [14]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.60%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.11%) [15]
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 181
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 324
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 740
Annual Return 2014 rr_AnnualReturn2014 7.99%
Annual Return 2015 rr_AnnualReturn2015 (0.91%)
Year to Date Return, Label rr_YearToDateReturnLabel R6 Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2016
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.54%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 3.74%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.68%)
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 (0.91%)
Since Inception rr_AverageAnnualReturnSinceInception 5.67%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
ARDUX
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2040 Portfolio R6
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses1 (expenses that you pay each year as a percentage of the value of your investment) [16]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. 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%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2040 Portfolio R6 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) and 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
70.80
%
NT Core Equity Plus Fund
3.25
%
NT Disciplined Growth Fund
3.08
%
NT Emerging Markets Fund
3.75
%
NT Equity Growth Fund
9.75
%
NT Global Real Estate Fund
2.15
%
NT Growth Fund
9.38
%
NT Heritage Fund
5.46
%
NT International Growth Fund
6.68
%
NT International Small-Mid Cap Fund
1.44
%
NT International Value Fund
4.86
%
NT Large Company Value Fund
11.54
%
NT Mid Cap Value Fund
6.31
%
NT Small Company Fund
3.15
%
 
Fixed-Income Securities (Bond Funds)
25.70
%
 
Global Bond Fund
4.28
%
 
NT High Income Fund
2.55
%
 
Inflation-Adjusted Bond Fund
5.15
%
 
NT Diversified Bond Fund
13.72
%
 
 
 
 
Cash Equivalents (Money Market Fund)
3.50
%
 
U.S. Government Money Market Fund
3.50
%
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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 R6, 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.
glidepathimagea52.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. 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 R6 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 is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit ipro.americancentury.com.
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 R6 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 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (2Q 2014): 4.00% Lowest Performance Quarter (3Q 2015): -6.25%
As of September 30, 2016, the most recent calendar quarter end, the fund’s R6 Class year-to-date return was 6.70%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2015
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO R6 | S&P Target Date To 2040 Index  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel S&P Target Date To 2040 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 (0.52%)
Since Inception rr_AverageAnnualReturnSinceInception 4.99%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2040 PORTFOLIO R6 | ONE CHOICE 2040 PORTFOLIO R6, R6 CLASS  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [17]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.61%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%) [18]
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 186
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 331
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 753
Annual Return 2014 rr_AnnualReturn2014 8.50%
Annual Return 2015 rr_AnnualReturn2015 (1.06%)
Year to Date Return, Label rr_YearToDateReturnLabel R6 Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2016
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.70%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.00%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (6.25%)
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 (1.06%)
Since Inception rr_AverageAnnualReturnSinceInception 6.08%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
ARDOX
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2045 Portfolio R6
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses1 (expenses that you pay each year as a percentage of the value of your investment) [19]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.09%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. 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 9% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 9.00%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2045 Portfolio R6 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) and 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
77.15
%
NT Core Equity Plus Fund
3.75
%
NT Disciplined Growth Fund
3.20
%
NT Emerging Markets Fund
4.75
%
NT Equity Growth Fund
10.25
%
NT Global Real Estate Fund
2.40
%
NT Growth Fund
10.20
%
NT Heritage Fund
6.40
%
NT International Growth Fund
6.80
%
NT International Small-Mid Cap Fund
1.75
%
NT International Value Fund
5.05
%
NT Large Company Value Fund
12.60
%
NT Mid Cap Value Fund
7.00
%
NT Small Company Fund
3.00
%
 
Fixed-Income Securities (Bond Funds)
21.85
%
 
Global Bond Fund
3.90
%
 
NT High Income Fund
2.15
%
 
Inflation-Adjusted Bond Fund
4.30
%
 
NT Diversified Bond Fund
11.50
%
 
 
 
 
Cash Equivalents (Money Market Fund)
1.00
%
 
U.S. Government Money Market Fund
1.00
%
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 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 R6, 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.
glidepathimagea52.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. 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 R6 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 is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit ipro.americancentury.com.
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 R6 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 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (2Q 2014): 4.16% Lowest Performance Quarter (3Q 2015): -6.80%
As of September 30, 2016, the most recent calendar quarter end, the fund’s R6 Class year-to-date return was 6.97%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2015
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO R6 | S&P Target Date To 2045 Index  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel S&P Target Date To 2045 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 (0.55%)
Since Inception rr_AverageAnnualReturnSinceInception 5.17%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2045 PORTFOLIO R6 | ONE CHOICE 2045 PORTFOLIO R6, R6 CLASS  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.60%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.03% [20]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.63%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.09%) [21]
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 193
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 343
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 778
Annual Return 2014 rr_AnnualReturn2014 8.91%
Annual Return 2015 rr_AnnualReturn2015 (1.14%)
Year to Date Return, Label rr_YearToDateReturnLabel R6 Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2016
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 6.97%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.16%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (6.80%)
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 (1.14%)
Since Inception rr_AverageAnnualReturnSinceInception 6.37%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
ARFEX
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2050 Portfolio R6
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses1 (expenses that you pay each year as a percentage of the value of your investment) [22]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.09%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. 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 7% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 7.00%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2050 Portfolio R6 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) and 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
81.40
%
NT Core Equity Plus Fund
4.50
%
NT Disciplined Growth Fund
3.33
%
NT Emerging Markets Fund
5.75
%
NT Equity Growth Fund
10.25
%
NT Global Real Estate Fund
2.65
%
NT Growth Fund
10.75
%
NT Heritage Fund
6.59
%
NT International Growth Fund
6.68
%
NT International Small-Mid Cap Fund
2.06
%
NT International Value Fund
5.24
%
NT Large Company Value Fund
13.41
%
NT Mid Cap Value Fund
6.94
%
NT Small Company Fund
3.25
%
 
Fixed-Income Securities (Bond Funds)
18.60
%
 
Global Bond Fund
3.53
%
 
NT High Income Fund
1.85
%
 
Inflation-Adjusted Bond Fund
3.70
%
 
NT Diversified Bond Fund
9.52
%
 
 
 
 
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 R6, 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.
glidepathimagea52.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. 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 R6 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 is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit ipro.americancentury.com.
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 R6 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 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (2Q 2014): 4.26% Lowest Performance Quarter (3Q 2015): -7.06%
As of September 30, 2016, the most recent calendar quarter end, the fund’s R6 Class year-to-date return was 7.08%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2015
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO R6 | S&P Target Date To 2050 Index  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel S&P Target Date To 2050 Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 (0.58%)
Since Inception rr_AverageAnnualReturnSinceInception 5.33%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2050 PORTFOLIO R6 | ONE CHOICE 2050 PORTFOLIO R6, R6 CLASS  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.62%
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% [23]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.66%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.09%) [24]
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 203
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 359
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 814
Annual Return 2014 rr_AnnualReturn2014 8.94%
Annual Return 2015 rr_AnnualReturn2015 (1.28%)
Year to Date Return, Label rr_YearToDateReturnLabel R6 Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2016
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 7.08%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.26%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (7.06%)
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 (1.28%)
Since Inception rr_AverageAnnualReturnSinceInception 6.42%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
AREUX
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2055 Portfolio R6
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.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses1 (expenses that you pay each year as a percentage of the value of your investment) [25]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. 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%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2055 Portfolio R6 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) and 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
83.90
%
NT Core Equity Plus Fund
4.50
%
NT Disciplined Growth Fund
3.45
%
NT Emerging Markets Fund
6.25
%
NT Equity Growth Fund
10.50
%
NT Global Real Estate Fund
2.90
%
NT Growth Fund
10.80
%
NT Heritage Fund
6.78
%
NT International Growth Fund
6.30
%
NT International Small-Mid Cap Fund
2.38
%
NT International Value Fund
5.43
%
NT Large Company Value Fund
13.98
%
NT Mid Cap Value Fund
6.88
%
NT Small Company Fund
3.75
%
 
Fixed-Income Securities (Bond Funds)
16.10
%
 
Global Bond Fund
3.15
%
 
NT High Income Fund
1.60
%
 
Inflation-Adjusted Bond Fund
3.20
%
 
NT Diversified Bond Fund
8.15
%
 
 
 

 
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 R6, 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.
glidepathimagea52.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. 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 R6 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 is not necessarily an indication of how the fund will perform in the future. For current performance information, including yields, please visit americancentury.com.
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 R6 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 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 Closing [Text Block] rr_BarChartClosingTextBlock
Highest Performance Quarter (2Q 2014): 4.32% Lowest Performance Quarter (3Q 2015): -7.37%
As of September 30, 2016, the most recent calendar quarter end, the fund’s R6 Class year-to-date return was 7.15%.
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns For the calendar year ended December 31, 2015
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO R6 | S&P Target Date To 2055 Plus Index  
Prospectus: rr_ProspectusTable  
Label rr_AverageAnnualReturnLabel S&P Target Date To 2055+ Index (reflects no deduction for fees, expenses or taxes)
1 Year rr_AverageAnnualReturnYear01 (0.54%)
Since Inception rr_AverageAnnualReturnSinceInception 5.52%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2055 PORTFOLIO R6 | ONE CHOICE 2055 PORTFOLIO R6, R6 CLASS  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.63%
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% [26]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.67%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%) [27]
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 205
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 364
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 826
Annual Return 2014 rr_AnnualReturn2014 9.21%
Annual Return 2015 rr_AnnualReturn2015 (1.28%)
Year to Date Return, Label rr_YearToDateReturnLabel R6 Class year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2016
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 7.15%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Performance Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2014
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.32%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Performance Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (7.37%)
Label rr_AverageAnnualReturnLabel R6 Class Return Before Taxes
1 Year rr_AverageAnnualReturnYear01 (1.28%)
Since Inception rr_AverageAnnualReturnSinceInception 6.60%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 2013
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO R6  
Prospectus: rr_ProspectusTable  
Trading Symbol dei_TradingSymbol
ARGDX
Risk/Return [Heading] rr_RiskReturnHeading One Choice 2060 Portfolio R6
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.
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) [28]
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination July 30, 2018
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. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund’s performance. During the period from September 30, 2015 (fund inception) to July 31, 2016, the fund’s portfolio turnover rate was 45% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 45.00%
Acquired Fund Fees and Expenses, Based on Estimates [Text] rr_AcquiredFundFeesAndExpensesBasedOnEstimates Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The example below is intended to help you compare the costs of investing in the fund with the costs of investing in other mutual funds.
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods, and that you earn a 5% return each year. The example also assumes that the fund’s operating expenses remain the same except that it reflects the rate and duration of any fee waivers noted in the table above. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading Principal Investment Strategies 
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
One Choice 2060 Portfolio R6 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) and 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 December 1, 2016, except the allocation to NT High Income Fund was changed from an equivalent allocation to High-Yield Fund on May 19, 2017.
Equity Securities (Stock Funds)
85.00
%
NT Core Equity Plus Fund
4.50
%
NT Disciplined Growth Fund
3.50
%
NT Emerging Markets Fund
6.50
%
NT Equity Growth Fund
10.75
%
NT Global Real Estate Fund
3.00
%
NT Growth Fund
11.00
%
NT Heritage Fund
6.75
%
NT International Growth Fund
6.00
%
NT International Small-Mid Cap Fund
2.50
%
NT International Value Fund
5.50
%
NT Large Company Value Fund
14.25
%
NT Mid Cap Value Fund
6.75
%
NT Small Company Fund
4.00
%
 
Fixed-Income Securities (Bond Funds)
15.00
%
 
Global Bond Fund
3.00
%
 
NT High Income Fund
1.50
%
 
Inflation-Adjusted Bond Fund
3.00
%
 
NT Diversified Bond Fund
7.50
%
 
 
 

 
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 R6, 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.
glidepathimagea52.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. 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 fund’s performance history is not available as of the date of this prospectus. When the fund has investment results for a full calendar year, this section will feature charts that show annual total returns, highest and lowest quarterly returns and average annual total returns for the fund. This information indicates the volatility of the fund’s historical returns from year to year.
Performance information is designed to help you see how fund returns can vary. Keep in mind that past performance does not predict how the fund will perform in the future.
For current performance information, including yields, please visit ipro.americancentury.com.
Performance One Year or Less [Text] rr_PerformanceOneYearOrLess The fund’s performance history is not available as of the date of this prospectus.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress ipro.americancentury.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Performance information is designed to help you see how fund returns can vary. Keep in mind that past performance does not predict how the fund will perform in the future.
American Century Asset Allocation Portfolio | ONE CHOICE 2060 PORTFOLIO R6 | ONE CHOICE 2060 PORTFOLIO R6, R6 CLASS  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.63%
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% [29]
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 0.67%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.10%) [30]
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 205
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 364
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 826
[1] The expense information in the table has been restated to reflect current fees.
[2] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[3] The advisor has agreed to waive 0.13 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.
[4] The expense information in the table has been restated to reflect current fees.
[5] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[6] The advisor has agreed to waive 0.13 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.
[7] The expense information in the table has been restated to reflect current fees.
[8] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[9] The advisor has agreed to waive 0.13 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.
[10] The expense information in the table has been restated to reflect current fees.
[11] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[12] The advisor has agreed to waive 0.12 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.
[13] The expense information in the table has been restated to reflect current fees.
[14] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[15] The advisor has agreed to waive 0.11 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.
[16] The expense information in the table has been restated to reflect current fees.
[17] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[18] The advisor has agreed to waive 0.10 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.
[19] The expense information in the table has been restated to reflect current fees.
[20] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[21] The advisor has agreed to waive 0.09 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.
[22] The expense information in the table has been restated to reflect current fees.
[23] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[24] The advisor has agreed to waive 0.09 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.
[25] The expense information in the table has been restated to reflect current fees.
[26] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[27] The advisor has agreed to waive 0.10 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.
[28] The expense information in the table has been restated to reflect current fees.
[29] Acquired Fund Fees and Expenses are based on estimated amounts for the current fiscal year.
[30] The advisor has agreed to waive 0.10 percentage points of the fund’s management fee. The advisor expects this waiver to continue until July 30, 2018 and cannot terminate it prior to such date without the approval of the Board of Directors.