Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName ALLIANCEBERNSTEIN BLENDED STYLE SERIES INC
Prospectus Date rr_ProspectusDate Dec. 31, 2013
AllianceBernstein 2020 Retirement Strategy
  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading ALLIANCEBERNSTEIN 2020 RETIREMENT STRATEGY
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The Strategy’s investment objective is to seek the highest total return (total return includes capital appreciation and income) over time consistent with its asset mix.
Expense [Heading] rr_ExpenseHeading FEES AND EXPENSES OF THE STRATEGY
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock This table describes the fees and expenses that you may pay if you buy and hold shares of the Strategy. You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AllianceBernstein Mutual Funds. More information about these and other discounts is available from your financial intermediary and in Investing in the Strategies--Sales Charge Reduction Programs for Class A Shares on page 72 of this Prospectus and in Purchase of Shares--Sales Charge Reduction Programs for Class A Shares on page 101 of the Strategy’s SAI.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption SHAREHOLDER FEES (fees paid directly from your investment) 
Operating Expenses Caption [Text] rr_OperatingExpensesCaption ANNUAL STRATEGY OPERATING EXPENSES (expenses that you pay each year as a
percentage of the value of your investment) 
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination December 31, 2014
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading PORTFOLIO TURNOVER
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock The Strategy (or an Underlying Portfolio) pays transaction costs, such as commissions, when it buys or sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Strategy shares are held in a taxable account. These transaction costs, which are not reflected in the Annual Strategy Operating Expenses or in the Examples, affect the Strategy’s performance. During the most recent fiscal year, the Strategy’s portfolio turnover rate (which reflects only purchases and sales of the Underlying Portfolios) was 9% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 9.00%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock Purchases of Class A shares in amounts of $1,000,000 or more, or by certain group retirement plans, may be subject to a 1%, 1-year CDSC, which may be subject to waiver in certain circumstances. Class B shares automatically convert to Class A shares after eight years. The CDSC decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the fourth year. For Class C shares the CDSC is 0% after the first year.
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AllianceBernstein Mutual Funds.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 100,000
Expense Example [Heading] rr_ExpenseExampleHeading EXAMPLES
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock The Examples are intended to help you compare the cost of investing in the Strategy with the cost of investing in other mutual funds. The Examples assume that you invest $10,000 in the Strategy for the time periods indicated and then redeem all of your shares at the end of those periods. The Examples also assume that your investment has a 5% return each year, that the Strategy’s operating expenses stay the same and that the fee waiver is in effect only for the first year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption For the share classes listed below, you would pay the following expenses if you did not redeem your shares at the end of the period:
Strategy [Heading] rr_StrategyHeading PRINCIPAL STRATEGIES
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock The Strategy seeks the highest total return over time consistent with its asset mix. Total return includes capital growth and income. To achieve its investment objective, the Strategy invests in a combination of portfolios of The AllianceBernstein Pooling Portfolios representing a variety of asset classes and investment styles (the “Underlying Portfolios”). The Strategy is managed to the specific year of planned retirement included in its name (the “retirement date”). The Strategy’s asset mixes will become more conservative each year until reaching the year approximately fifteen years after the retirement date (the “target year”) at which time the asset allocation mix will become static. This reflects the objective of pursuing the maximum amount of capital growth, consistent with a reasonable amount of risk, during the investor’s pre-retirement and early retirement years. After retirement the Strategy’s investment mix anticipates that an investor may take withdrawals from his or her account to provide supplemental retirement income.

After the retirement date of the Strategy, its asset mix seeks to minimize the likelihood that an investor in the Strategy experiences a significant loss of capital at a more advanced age. The asset mix for the Strategy will continue to change after the Strategy’s retirement date with an increasing exposure to investments in fixed-income securities and short-term bonds until fifteen years after the Strategy’s retirement date. Thereafter, the target asset allocation for the Strategy will generally be fixed. The static allocation of the Strategy’s asset mix will be 27.5% short-duration bonds, 37.5% other fixed-income securities, 12.5% Volatility Management Portfolio, 15.5% other equities and 7% Multi-Asset Real Return Portfolio.

The Underlying Portfolios will include a Portfolio, the Volatility Management Portfolio, that is designed to reduce the overall effect of equity market volatility on the Strategy and the effects of adverse equity market conditions on its performance. The Volatility Management Portfolio will be a component of the Strategy’s equity asset allocation. Under normal market conditions, this Underlying Portfolio will invest predominantly in equity securities. If the Adviser determines that the equity markets pose disproportionate risks, the Adviser will reduce (or eliminate) this Underlying Portfolio’s equity investments and invest in fixed-income securities or other non-equity asset classes to reduce the risks of the Strategy’s investments in equity securities.

The Adviser will allow the relative weightings of the Strategy’s asset classes to vary in response to the markets, but ordinarily only by plus/minus 5%. Beyond those ranges, the Adviser will generally rebalance the portfolio toward the target asset allocation for the Strategy. However, there may be occasions when those ranges will expand to 10% of the Strategy’s portfolio due to, among other things, appreciation of one of the asset classes.

The following chart illustrates how the asset mix of the Strategy will vary over time. In general, the asset mix of the Strategy will gradually shift from one comprised largely of Underlying Portfolios that emphasize investments in stocks to one that is comprised of a mixture of Underlying Portfolios that invest in bonds (including short-duration bonds) and stocks.

Years Before Retirement
45 40 35 30 25
US Diversified Value 20.50% 20.50% 20.50% 19.50% 18.25%
US Large Cap Growth 20.50% 20.50% 20.50% 19.50% 18.25%
US SMID Value 6.50% 6.50% 6.50% 6.00% 5.75%
US SMID Growth 6.50% 6.50% 6.50% 6.00% 5.75%
International Value 18.00% 18.00% 18.00% 17.00% 16.00%
International Growth 18.00% 18.00% 18.00% 17.00% 16.00%
Multi-Asset Real Return 5.00% 5.00% 5.00% 5.00% 5.00%
Volatility Management 0.00% 0.00% 0.00% 5.00% 10.00%
High Yield 0.00% 0.00% 0.00% 0.00% 0.00%
Global Bonds 5.00% 5.00% 5.00% 5.00% 5.00%
Inflation-Protected
    Securities 0.00% 0.00% 0.00% 0.00% 0.00%
Short Duration Bonds 0.00% 0.00% 0.00% 0.00% 0.00%
Years Before Retirement
20 15 10 5
US Diversified Value 16.25% 13.75% 11.25% 9.75%
US Large Cap Growth 16.25% 13.75% 11.25% 9.75%
US SMID Value 5.00% 4.25% 3.50% 2.75%
US SMID Growth 5.00% 4.25% 3.50% 2.75%
International Value 14.00% 12.00% 9.75% 8.50%
International Growth 14.00% 12.00% 9.75% 8.50%
Multi-Asset Real Return 7.00% 8.50% 10.00% 10.00%
Volatility Management 12.50% 17.50% 20.00% 20.00%
High Yield 5.00% 7.00% 7.00% 7.00%
Global Bonds 5.00% 7.00% 10.00% 12.00%
Inflation-Protected
    Securities 0.00% 0.00% 4.00% 9.00%
Short Duration Bonds 0.00% 0.00% 0.00% 0.00%
Retirement Date Years After Retirement
0 5 10 15 20
US Diversified Value 8.50% 6.45% 5.25% 4.00% 4.00%
US Large Cap Growth 8.50% 6.45% 5.25% 4.00% 4.00%
US SMID Value 2.00% 1.50% 1.00% 0.75% 0.75%
US SMID Growth 2.00% 1.50% 1.00% 0.75% 0.75%
International Value 8.50% 7.00% 4.00% 3.00% 3.00%
International Growth 7.00% 5.30% 4.00% 3.00% 3.00%
Multi-Asset Real Return 10.00% 8.50% 7.00% 7.00% 7.00%
Volatility Management 20.00% 20.00% 17.50% 12.50% 12.50%
High Yield 7.00% 5.00% 2.50% 0.00% 0.00%
Global Bonds 14.00% 16.00% 19.50% 22.50% 22.50%
Inflation-Protected
    Securities 14.00% 15.00% 15.00% 15.00% 15.00%
Short Duration Bonds 0.00% 9.00% 18.00% 27.50% 27.50%
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock The value of your investment in the Strategy will change with changes in the values of the Strategy's investments in the Underlying Portfolios. There is no assurance that the Strategy will provide an investor with adequate income at or through retirement. The degree to which the following risks apply varies according to the Strategy's asset allocation.
  • MARKET RISK: The value of the Strategy's investments will fluctuate as the stock or bond market fluctuates. The value of its investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market. It includes the risk that a particular style of investing, such as growth or value, may be underperforming the stock market generally.
  • INTEREST RATE RISK: Changes in interest rates will affect the value of the Strategy's investments in Underlying Portfolios that invest in fixed-income securities. When interest rates rise, the value of investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest rate risk is generally greater for fixed-income securities with longer maturities or durations.
  • CREDIT RISK: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security. Investments in fixed-income securities with lower ratings are subject to a higher probability that an issuer will default or fail to meet its payment obligations.
  • ALLOCATION RISK: The allocation of investments among the Underlying Portfolios' different investment styles, such as growth or value, equity or debt securities, or U.S. or non-U.S. securities, may have a more significant effect on the Strategy's NAV when one of these investments is performing more poorly than the other.
  • INFLATION RISK: This is the risk that the value of assets or income from the Strategy's investments in the Underlying Portfolios will be less in the future as inflation decreases the value of money. As inflation increases, the value of each Underlying Portfolio's assets can decline as can the value of that Underlying Portfolio's distributions.
  • FOREIGN (NON-U.S.) RISK: Investments in non-U.S. issuers may involve more risk than investments in U.S. issuers. These securities may fluctuate more widely in price and may be less liquid due to adverse market, economic, political, regulatory or other factors. This risk is greater when the Strategy has a higher asset allocation of Underlying Portfolios that invest in non-U.S. issuers.
  • EMERGING MARKET RISK: Investments in emerging market countries may involve more risk than investments in other foreign countries because the markets in emerging market countries are less developed and less liquid as well as subject to increased economic, political, regulatory and other uncertainties.
  • CURRENCY RISK: Fluctuations in currency exchange rates may negatively affect the value of the Strategy's investments or reduce its returns.
  • CAPITALIZATION RISK: Investments in small- and mid-capitalization companies by Underlying Portfolios tend to be more volatile than investments in large-capitalization companies. Investments in small-capitalization companies may have additional risks because these companies often have limited product lines, markets, or financial resources.
  • FOCUSED PORTFOLIO RISK: The Underlying Portfolios that invest in a limited number of companies may have more risk because changes in the value of a single security may have a more significant effect, either negative or positive, on the Strategy's NAV.
  • DERIVATIVES RISK: Derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses, and may be subject to counterparty risk to a greater degree than more traditional investments.
  • LEVERAGE RISK: Borrowing money or other leverage may make an Underlying Portfolio's investments more volatile because leverage tends to exaggerate the effect of any increase or decrease in the value of its investments. An Underlying Portfolio may create leverage through the use of certain portfolio management techniques such as reverse repurchase agreements or forward commitments, or by borrowing money.
  • MANAGEMENT RISK: The Strategy is subject to management risk because it is an actively-managed investment fund. The Adviser will apply its investment techniques and risk analyses in making investment decisions for the Strategy, but there is no guarantee that its techniques will produce the intended results.
As with all investments, you may lose money by investing in the Strategy.
Risk Lose Money [Text] rr_RiskLoseMoney As with all investments, you may lose money by investing in the Strategy.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading BAR CHART AND PERFORMANCE INFORMATION
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock The bar chart and performance information provide an indication of the historical risk of an investment in the Strategy by showing:
  • how the Strategy’s performance changed from year to year over the life of the Strategy; and
  • how the Strategy’s average annual returns for one year, five years and since inception compare to those of a broad-based securities market index.
You may obtain updated performance information on the Strategy’s website at www.AllianceBernstein.com (click on “Individuals--U.S.” then “Products & Performance”).

The Strategy’s past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns
  • how the Strategy’s performance changed from year to year over the life of the Strategy; and
  • how the Strategy’s average annual returns for one year, five years and since inception compare to those of a broad-based securities market index.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.AllianceBernstein.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Strategy's past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future.
Bar Chart [Heading] rr_BarChartHeading BAR CHART
Bar Chart Narrative [Text Block] rr_BarChartNarrativeTextBlock The annual returns in the bar chart are for the Strategy’s Class A shares and do not reflect sales loads. If sales loads were reflected, returns would be less than those shown. Through September 30, 2013, the year-to-date unannualized return for Class A shares was 9.99%.
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The annual returns in the bar chart are for the Strategy’s Class A shares and do not reflect sales loads.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock During the period shown in the bar chart, the Strategy’s:

BEST QUARTER WAS UP 17.87%, 2ND QUARTER, 2009; AND WORST QUARTER WAS DOWN
-20.86%, 4TH QUARTER, 2008.
Performance Table Heading rr_PerformanceTableHeading PERFORMANCE TABLE
AVERAGE ANNUAL TOTAL RETURNS

(For the periods ended December 31, 2012)
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes The Composite Benchmark reflects no deductions for fees, expenses or taxes.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate Are estimates based on the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes; actual after-tax returns depend on an individual investor’s tax situation and are likely to differ from those shown;
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred Are not relevant to investors who hold Strategy shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns: -Are shown for Class A shares only and will vary for the other Classes of shares because these Classes have different expense ratios;
AllianceBernstein 2020 Retirement Strategy | CLASS A
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.25%
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther none [1]
Exchange Fee rr_ExchangeFee none
Management Fees rr_ManagementFeesOverAssets 0.60%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.30%
Other Expenses: Transfer Agent rr_Component1OtherExpensesOverAssets 0.21%
Other Expenses rr_Component2OtherExpensesOverAssets 0.13%
Total Other Expenses rr_OtherExpensesOverAssets 0.34%
Acquired Fund Fees and Expenses (Underlying Portfolios) rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Total Annual Strategy Operating Expenses rr_ExpensesOverAssets 1.28%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.26%) [2]
Total Annual Strategy Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.02%
After 1 Year rr_ExpenseExampleYear01 525
After 3 Years rr_ExpenseExampleYear03 789
After 5 Years rr_ExpenseExampleYear05 1,074
After 10 Years rr_ExpenseExampleYear10 1,883
2003 rr_AnnualReturn2003   
2004 rr_AnnualReturn2004   
2005 rr_AnnualReturn2005   
2006 rr_AnnualReturn2006 16.17%
2007 rr_AnnualReturn2007 5.00%
2008 rr_AnnualReturn2008 (38.20%)
2009 rr_AnnualReturn2009 31.93%
2010 rr_AnnualReturn2010 12.92%
2011 rr_AnnualReturn2011 (4.05%)
2012 rr_AnnualReturn2012 11.14%
Year to Date Return, Label rr_YearToDateReturnLabel year-to-date
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2013
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 9.99%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel BEST QUARTER
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.87%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel WORST QUARTER
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.86%)
1 YEAR rr_AverageAnnualReturnYear01 6.37% [3]
5 YEAR rr_AverageAnnualReturnYear05 (1.23%) [3]
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 2.56% [3],[4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005 [3]
AllianceBernstein 2020 Retirement Strategy | CLASS B
  
Risk/Return: rr_RiskReturnAbstract  
Shareholder Fees Column [Text] rr_ShareholderFeesColumnName (NOT CURRENTLY OFFERED TO NEW INVESTORS)
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther 4.00% [5]
Exchange Fee rr_ExchangeFee none
Management Fees rr_ManagementFeesOverAssets 0.60%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses: Transfer Agent rr_Component1OtherExpensesOverAssets 0.24%
Other Expenses rr_Component2OtherExpensesOverAssets 0.13%
Total Other Expenses rr_OtherExpensesOverAssets 0.37%
Acquired Fund Fees and Expenses (Underlying Portfolios) rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Total Annual Strategy Operating Expenses rr_ExpensesOverAssets 2.01%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.29%) [2]
Total Annual Strategy Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.72%
After 1 Year rr_ExpenseExampleYear01 575
After 3 Years rr_ExpenseExampleYear03 803
After 5 Years rr_ExpenseExampleYear05 1,056
After 10 Years rr_ExpenseExampleYear10 2,126
After 1 Year rr_ExpenseExampleNoRedemptionYear01 175
After 3 Years rr_ExpenseExampleNoRedemptionYear03 603
After 5 Years rr_ExpenseExampleNoRedemptionYear05 1,056
After 10 Years rr_ExpenseExampleNoRedemptionYear10 2,126
1 YEAR rr_AverageAnnualReturnYear01 6.37%
5 YEAR rr_AverageAnnualReturnYear05 (1.07%)
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 2.43% [4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005
AllianceBernstein 2020 Retirement Strategy | CLASS C
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther 1.00% [6]
Exchange Fee rr_ExchangeFee none
Management Fees rr_ManagementFeesOverAssets 0.60%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses: Transfer Agent rr_Component1OtherExpensesOverAssets 0.24%
Other Expenses rr_Component2OtherExpensesOverAssets 0.13%
Total Other Expenses rr_OtherExpensesOverAssets 0.37%
Acquired Fund Fees and Expenses (Underlying Portfolios) rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Total Annual Strategy Operating Expenses rr_ExpensesOverAssets 2.01%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.29%) [2]
Total Annual Strategy Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.72%
After 1 Year rr_ExpenseExampleYear01 275
After 3 Years rr_ExpenseExampleYear03 603
After 5 Years rr_ExpenseExampleYear05 1,056
After 10 Years rr_ExpenseExampleYear10 2,314
After 1 Year rr_ExpenseExampleNoRedemptionYear01 175
After 3 Years rr_ExpenseExampleNoRedemptionYear03 603
After 5 Years rr_ExpenseExampleNoRedemptionYear05 1,056
After 10 Years rr_ExpenseExampleNoRedemptionYear10 2,314
1 YEAR rr_AverageAnnualReturnYear01 9.37%
5 YEAR rr_AverageAnnualReturnYear05 (1.05%)
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 2.45% [4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005
AllianceBernstein 2020 Retirement Strategy | ADVISOR CLASS
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther none
Exchange Fee rr_ExchangeFee none
Management Fees rr_ManagementFeesOverAssets 0.60%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses: Transfer Agent rr_Component1OtherExpensesOverAssets 0.22%
Other Expenses rr_Component2OtherExpensesOverAssets 0.13%
Total Other Expenses rr_OtherExpensesOverAssets 0.35%
Acquired Fund Fees and Expenses (Underlying Portfolios) rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Total Annual Strategy Operating Expenses rr_ExpensesOverAssets 0.99%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.27%) [2]
Total Annual Strategy Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 0.72%
After 1 Year rr_ExpenseExampleYear01 74
After 3 Years rr_ExpenseExampleYear03 288
After 5 Years rr_ExpenseExampleYear05 521
After 10 Years rr_ExpenseExampleYear10 1,188
1 YEAR rr_AverageAnnualReturnYear01 11.41%
5 YEAR rr_AverageAnnualReturnYear05 (0.10%)
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 3.46% [4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005
AllianceBernstein 2020 Retirement Strategy | CLASS R
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther none
Exchange Fee rr_ExchangeFee none
Management Fees rr_ManagementFeesOverAssets 0.60%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses: Transfer Agent rr_Component1OtherExpensesOverAssets 0.25%
Other Expenses rr_Component2OtherExpensesOverAssets 0.13%
Total Other Expenses rr_OtherExpensesOverAssets 0.38%
Acquired Fund Fees and Expenses (Underlying Portfolios) rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Total Annual Strategy Operating Expenses rr_ExpensesOverAssets 1.52%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.30%) [2]
Total Annual Strategy Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 1.22%
After 1 Year rr_ExpenseExampleYear01 124
After 3 Years rr_ExpenseExampleYear03 451
After 5 Years rr_ExpenseExampleYear05 801
After 10 Years rr_ExpenseExampleYear10 1,787
1 YEAR rr_AverageAnnualReturnYear01 10.93%
5 YEAR rr_AverageAnnualReturnYear05 (0.58%)
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 2.96% [4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005
AllianceBernstein 2020 Retirement Strategy | CLASS K
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther none
Exchange Fee rr_ExchangeFee none
Management Fees rr_ManagementFeesOverAssets 0.60%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses: Transfer Agent rr_Component1OtherExpensesOverAssets 0.20%
Other Expenses rr_Component2OtherExpensesOverAssets 0.13%
Total Other Expenses rr_OtherExpensesOverAssets 0.33%
Acquired Fund Fees and Expenses (Underlying Portfolios) rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Total Annual Strategy Operating Expenses rr_ExpensesOverAssets 1.22%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.25%) [2]
Total Annual Strategy Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 0.97%
After 1 Year rr_ExpenseExampleYear01 99
After 3 Years rr_ExpenseExampleYear03 362
After 5 Years rr_ExpenseExampleYear05 646
After 10 Years rr_ExpenseExampleYear10 1,455
1 YEAR rr_AverageAnnualReturnYear01 11.16%
5 YEAR rr_AverageAnnualReturnYear05 (0.32%)
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 3.22% [4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005
AllianceBernstein 2020 Retirement Strategy | CLASS I
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) rr_MaximumDeferredSalesChargeOverOther none
Exchange Fee rr_ExchangeFee none
Management Fees rr_ManagementFeesOverAssets 0.60%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses: Transfer Agent rr_Component1OtherExpensesOverAssets 0.10%
Other Expenses rr_Component2OtherExpensesOverAssets 0.13%
Total Other Expenses rr_OtherExpensesOverAssets 0.23%
Acquired Fund Fees and Expenses (Underlying Portfolios) rr_AcquiredFundFeesAndExpensesOverAssets 0.04%
Total Annual Strategy Operating Expenses rr_ExpensesOverAssets 0.87%
Fee Waiver and/or Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.15%) [2]
Total Annual Strategy Operating Expenses After Fee Waiver and/or Expense Reimbursement rr_NetExpensesOverAssets 0.72%
After 1 Year rr_ExpenseExampleYear01 74
After 3 Years rr_ExpenseExampleYear03 263
After 5 Years rr_ExpenseExampleYear05 468
After 10 Years rr_ExpenseExampleYear10 $ 1,059
1 YEAR rr_AverageAnnualReturnYear01 11.53%
5 YEAR rr_AverageAnnualReturnYear05 (0.07%)
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 3.47% [4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005
AllianceBernstein 2020 Retirement Strategy | Return After Taxes on Distributions | CLASS A
  
Risk/Return: rr_RiskReturnAbstract  
1 YEAR rr_AverageAnnualReturnYear01 5.98% [3]
5 YEAR rr_AverageAnnualReturnYear05 (1.85%) [3]
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 1.93% [3],[4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005 [3]
AllianceBernstein 2020 Retirement Strategy | Return After Taxes on Distributions and Sale of Strategy Shares | CLASS A
  
Risk/Return: rr_RiskReturnAbstract  
1 YEAR rr_AverageAnnualReturnYear01 4.48% [3]
5 YEAR rr_AverageAnnualReturnYear05 (1.28%) [3]
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 1.94% [3],[4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005 [3]
AllianceBernstein 2020 Retirement Strategy | S&P 500 Stock Index (reflects no deduction for fees, taxes or expenses)
  
Risk/Return: rr_RiskReturnAbstract  
1 YEAR rr_AverageAnnualReturnYear01 16.00%
5 YEAR rr_AverageAnnualReturnYear05 1.66%
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 4.32% [4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005
AllianceBernstein 2020 Retirement Strategy | Barclays Capital U.S. Aggregate Bond Index (reflects no deduction for fees, taxes or expenses)
  
Risk/Return: rr_RiskReturnAbstract  
1 YEAR rr_AverageAnnualReturnYear01 4.21%
5 YEAR rr_AverageAnnualReturnYear05 5.95%
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 5.50% [4]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005
AllianceBernstein 2020 Retirement Strategy | Composite Benchmark
  
Risk/Return: rr_RiskReturnAbstract  
1 YEAR rr_AverageAnnualReturnYear01 13.20% [7]
5 YEAR rr_AverageAnnualReturnYear05 1.56% [7]
SINCE INCEPTION rr_AverageAnnualReturnSinceInception 4.73% [4],[7]
INCEPTION DATE rr_AverageAnnualReturnInceptionDate Sep. 01, 2005 [7]
[1] Purchases of Class A shares in amounts of $1,000,000 or more, or by certain group retirement plans, may be subject to a 1%, 1-year CDSC, which may be subject to waiver in certain circumstances.
[2] The fee waiver and/or expense reimbursement agreement will remain in effect until December 31, 2014 and will be automatically extended for one-year terms thereafter unless terminated by the Adviser upon 60 days' notice to the Strategy prior to that date.
[3] After-tax returns: -Are shown for Class A shares only and will vary for the other Classes of shares because these Classes have different expense ratios; -Are estimates based on the highest historical individual federal marginal income tax rates, and do not reflect the impact of state and local taxes; actual after-tax returns depend on an individual investor’s tax situation and are likely to differ from those shown; and -Are not relevant to investors who hold Strategy shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
[4] Inception date is 9/1/05 for Class A, Class B, Class C, Class R, Class K, Class I and Advisor Class shares.
[5] Class B shares automatically convert to Class A shares after eight years. The CDSC decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the fourth year.
[6] For Class C shares the CDSC is 0% after the first year.
[7] The Composite Benchmark shows how the Strategy's performance compares with the returns of an index of securities similar to those in which the Strategy invests. The Composite Benchmark is derived by applying the Strategy's target allocations over time to the results of the following benchmarks, as applicable: for U.S. stocks, Russell 3000 Index; for non-U.S. stocks, Morgan Stanley Capital International (MSCI) Europe, Australasia, Far East (EAFE) Index; for intermediate bonds, Barclays Capital U.S. Aggregate Bond Index; for short-term bonds, BofA Merrill Lynch (ML) 1-3 Year Treasury Index; for Inflation-Protected Securities, Barclays Capital 1-10 Year TIPS Index; for high-yield bonds, Custom High Yield Composite Index. The Composite Benchmark reflects no deductions for fees, expenses or taxes.