Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	ALLIANCEBERNSTEIN TRUST
Prospectus Date	rr_ProspectusDate	Mar. 01, 2012
AllianceBernstein Discovery Value Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	ALLIANCEBERNSTEIN DISCOVERY VALUE FUND (FORMERLY, ALLIANCEBERNSTEIN SMALL/MID CAP VALUE FUND)
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund's investment objective is long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
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 Fund. 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 Funds--Sales Charge Reduction Programs for Class A Shares on page 55 of this Prospectus and in Purchase of Shares--Sales Charge Reduction Programs for Class A Shares on page 115 of the Funds' SAI.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys 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 Fund shares are held in a taxable account. These transaction costs, which are not reflected in the Annual Fund Operating Expenses or in the Examples, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 72% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	72.00%
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 Fund with the cost of investing in other mutual funds. The Examples assume 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. The Examples also assume that your investment has a 5% return each year and that the Fund's operating expenses stay the same. 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 Fund invests primarily in a diversified portfolio of equity securities of small- to mid-capitalization U.S. companies, generally representing 60 to 125 companies. Under normal circumstances, the Fund invests at least 80% of its net assets in securities of small- to mid-capitalization companies. For purposes of this policy, small- to mid-capitalization companies are those that, at the time of investment, fall within the capitalization range between the smallest company in the Russell 2500(TM) Value Index and the greater of $5 billion or the market capitalization of the largest company in the Russell 2500(TM) Value Index. Because the Fund's definition of small- to mid-capitalization companies is dynamic, the lower and upper limits on market capitalization will change with the markets. As of December 31, 2011, there were approximately 1,693 small- to mid-capitalization companies, representing a market capitalization range from approximately $37 million to approximately $7.463 billion. The Fund invests in companies that are determined by the Adviser to be undervalued, using the Adviser's fundamental value approach. In selecting securities for the Fund's portfolio, the Adviser uses its fundamental and quantitative research to identify companies whose long-term earnings power is not reflected in the current market price of their securities. In selecting securities for the Fund's portfolio, the Adviser looks for companies with attractive valuation (for example, with low price to book ratios) and compelling success factors (for example, momentum and return on equity). The Adviser then uses this information to calculate an expected return. Returns and rankings are updated on a daily basis. The rankings are used to determine prospective candidates for further fundamental research and, subsequently, possible addition to the portfolio. Typically, the Adviser's fundamental research analysts focus their research on the most attractive 20% of the universe. The Adviser typically projects a company's financial performance over a full economic cycle, including a trough and a peak, within the context of forecasts for real economic growth, inflation and interest rate changes. The Adviser focuses on the valuation implied by the current price, relative to the earnings the company will be generating five years from now, or "normalized" earnings, assuming average mid-economic cycle growth for the fifth year. The Fund's management team and other senior investment professionals work in close collaboration to weigh each investment opportunity identified by the research staff relative to the entire portfolio and determine the timing and position size for purchases and sales. Analysts remain responsible for monitoring new developments that would affect the securities they cover. The team will generally sell a security when it no longer meets appropriate valuation criteria, although sales may be delayed when positive return trends are favorable. Typically, growth in the size of a company's market capitalization relative to other domestically traded companies will not cause the Fund to dispose of the security. The Adviser seeks to manage overall portfolio volatility relative to the universe of companies that comprise the lowest 20% of the total U.S. market capitalization by favoring promising securities that offer the best balance between return and targeted risk. At times, the Fund may favor or disfavor a particular sector compared to that universe of companies. The Fund may invest significantly in companies involved in certain sectors that constitute a material portion of the universe of small- and mid-capitalization companies, such as financial services and consumer services. The Fund may enter into derivatives transactions, such as options, futures contracts, forwards, and swap agreements. The Fund may use options strategies involving the purchase and/or writing of various combinations of call and/or put options, including on individual securities and stock indexes, futures contracts (including futures contracts on individual securities and stock indexes) or shares of ETFs. These transactions may be used, for example, in an effort to earn extra income, to adjust exposure to individual securities or markets, or to protect all or a portion of the Fund's portfolio from a decline in value, sometimes within certain ranges. The Fund may, at times, invest in shares of ETFs in lieu of making direct investments in equity securities. ETFs may provide more efficient and economical exposure to the type of companies and geographic locations in which the Fund seeks to invest than direct investments.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	MARKET RISK: The value of the Fund'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 the Fund's value approach, may be underperforming the market generally. CAPITALIZATION RISK: Investments in small- and mid-capitalization companies may be more volatile than investments in large-capitalization companies. Investments in small-capitalization companies may have additional risks because these companies have limited product lines, markets or financial resources. FOREIGN (NON-U.S.) RISK: Investments in securities of non-U.S. issuers may involve more risk than those of 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. CURRENCY RISK: Fluctuations in currency exchange rates may negatively affect the value of the Fund's investments or reduce its returns. DERIVATIVES RISK: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Fund, and may be subject to counterparty risk to a greater degree than more traditional investments. MANAGEMENT RISK: The Fund 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 Fund, 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 Fund.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with all investments, you may lose money by investing in the Fund.
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 Fund by showing: how the Fund's performance changed from year to year over the life of the Fund; and how the Fund's average annual returns for one, five and ten years compare to those of a broad-based securities market index. You may obtain updated performance information on the Fund's website at www.AllianceBernstein.com (click on "Pricing & Performance"). The Fund'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 Fund's performance changed from year to year over the life of the Fund; and how the Fund's average annual returns for one, five and ten years 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 Fund'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 Fund'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, 2012, the year-to-date unannualized return for Class A shares was 11.88%.
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The annual returns in the bar chart are for the Fund's Class A shares and do not reflect sales loads.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Calendar Year End (%) During the period shown in the bar chart, the Fund's: BEST QUARTER WAS UP 24.44%, 3RD QUARTER, 2009; AND WORST QUARTER WAS DOWN -25.46%, 4TH QUARTER, 2008.
Performance Table Heading	rr_PerformanceTableHeading	PERFORMANCE TABLE AVERAGE ANNUAL TOTAL RETURNS (For the periods ended December 31, 2011)
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;
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Are not relevant to investors who hold fund 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	Are shown for Class A shares only and will vary for Class B, Class C and Advisor Class shares because these Classes have different expense ratios;
AllianceBernstein Discovery Value Fund | CLASS A SHARES
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.30%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.17%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.05%
Total Other Expenses	rr_OtherExpensesOverAssets	0.22%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.27%
After 1 Year	rr_ExpenseExampleYear01	549
After 3 Years	rr_ExpenseExampleYear03	811
After 5 Years	rr_ExpenseExampleYear05	1,092
After 10 Years	rr_ExpenseExampleYear10	1,894
2002	rr_AnnualReturn2002	(8.19%)
2003	rr_AnnualReturn2003	41.92%
2004	rr_AnnualReturn2004	18.91%
2005	rr_AnnualReturn2005	7.89%
2006	rr_AnnualReturn2006	13.65%
2007	rr_AnnualReturn2007	2.32%
2008	rr_AnnualReturn2008	(34.56%)
2009	rr_AnnualReturn2009	41.81%
2010	rr_AnnualReturn2010	26.51%
2011	rr_AnnualReturn2011	(8.40%)
Year to Date Return, Label	rr_YearToDateReturnLabel	year-to-date
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2012
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	11.88%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	BEST QUARTER
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	24.44%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	WORST QUARTER
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(25.46%)
1 YEAR	rr_AverageAnnualReturnYear01	(12.28%)	[1]
5 YEARS	rr_AverageAnnualReturnYear05	1.05%	[1]
10 YEARS	rr_AverageAnnualReturnYear10	7.18%	[1]
AllianceBernstein Discovery Value Fund | CLASS B SHARES
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_MaximumDeferredSalesChargeOverOfferingPrice	4.00%	[2]
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.23%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.05%
Total Other Expenses	rr_OtherExpensesOverAssets	0.28%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.03%
After 1 Year	rr_ExpenseExampleYear01	606
After 3 Years	rr_ExpenseExampleYear03	837
After 5 Years	rr_ExpenseExampleYear05	1,093
After 10 Years	rr_ExpenseExampleYear10	2,163
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	206
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	637
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,093
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	2,163
1 YEAR	rr_AverageAnnualReturnYear01	(12.02%)
5 YEARS	rr_AverageAnnualReturnYear05	1.71%
10 YEARS	rr_AverageAnnualReturnYear10	7.20%
AllianceBernstein Discovery Value Fund | CLASS C SHARES
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[3]
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.19%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.05%
Total Other Expenses	rr_OtherExpensesOverAssets	0.24%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.99%
After 1 Year	rr_ExpenseExampleYear01	302
After 3 Years	rr_ExpenseExampleYear03	624
After 5 Years	rr_ExpenseExampleYear05	1,073
After 10 Years	rr_ExpenseExampleYear10	2,317
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	202
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	624
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	1,073
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	2,317
1 YEAR	rr_AverageAnnualReturnYear01	(9.93%)
5 YEARS	rr_AverageAnnualReturnYear05	1.20%
10 YEARS	rr_AverageAnnualReturnYear10	6.89%
AllianceBernstein Discovery Value Fund | ADVISOR CLASS SHARES
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.17%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.05%
Total Other Expenses	rr_OtherExpensesOverAssets	0.22%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.97%
After 1 Year	rr_ExpenseExampleYear01	99
After 3 Years	rr_ExpenseExampleYear03	309
After 5 Years	rr_ExpenseExampleYear05	536
After 10 Years	rr_ExpenseExampleYear10	1,190
1 YEAR	rr_AverageAnnualReturnYear01	(8.16%)
5 YEARS	rr_AverageAnnualReturnYear05	2.22%
10 YEARS	rr_AverageAnnualReturnYear10	7.96%
AllianceBernstein Discovery Value Fund | CLASS R SHARES
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.26%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.05%
Total Other Expenses	rr_OtherExpensesOverAssets	0.31%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.56%
After 1 Year	rr_ExpenseExampleYear01	159
After 3 Years	rr_ExpenseExampleYear03	493
After 5 Years	rr_ExpenseExampleYear05	850
After 10 Years	rr_ExpenseExampleYear10	1,856
1 YEAR	rr_AverageAnnualReturnYear01	(8.63%)	[4]
5 YEARS	rr_AverageAnnualReturnYear05	1.73%	[4]
10 YEARS	rr_AverageAnnualReturnYear10	7.47%	[4]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Nov. 03, 2003	[4]
AllianceBernstein Discovery Value Fund | CLASS K SHARES
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.20%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.05%
Total Other Expenses	rr_OtherExpensesOverAssets	0.25%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.25%
After 1 Year	rr_ExpenseExampleYear01	127
After 3 Years	rr_ExpenseExampleYear03	397
After 5 Years	rr_ExpenseExampleYear05	686
After 10 Years	rr_ExpenseExampleYear10	1,511
1 YEAR	rr_AverageAnnualReturnYear01	(8.42%)	[4]
5 YEARS	rr_AverageAnnualReturnYear05	1.96%	[4]
10 YEARS	rr_AverageAnnualReturnYear10	7.70%	[4]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2005	[4]
AllianceBernstein Discovery Value Fund | CLASS I SHARES
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.11%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.05%
Total Other Expenses	rr_OtherExpensesOverAssets	0.16%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.91%
After 1 Year	rr_ExpenseExampleYear01	93
After 3 Years	rr_ExpenseExampleYear03	290
After 5 Years	rr_ExpenseExampleYear05	504
After 10 Years	rr_ExpenseExampleYear10	1,120
1 YEAR	rr_AverageAnnualReturnYear01	(8.20%)	[4]
5 YEARS	rr_AverageAnnualReturnYear05	2.21%	[4]
10 YEARS	rr_AverageAnnualReturnYear10	7.96%	[4]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Mar. 01, 2005	[4]
AllianceBernstein Discovery Value Fund | Return After Taxes on Distributions | CLASS A SHARES
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	(13.07%)	[1]
5 YEARS	rr_AverageAnnualReturnYear05	0.54%	[1]
10 YEARS	rr_AverageAnnualReturnYear10	6.37%	[1]
AllianceBernstein Discovery Value Fund | Return After Taxes on Distributions and Sale of Fund Shares | CLASS A SHARES
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	(6.99%)	[1]
5 YEARS	rr_AverageAnnualReturnYear05	0.84%	[1]
10 YEARS	rr_AverageAnnualReturnYear10	6.18%	[1]
AllianceBernstein Discovery Value Fund | Russell 2500(TM) Value Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	(3.36%)
5 YEARS	rr_AverageAnnualReturnYear05	(0.58%)
10 YEARS	rr_AverageAnnualReturnYear10	7.16%
AllianceBernstein Discovery Value Fund | Russell 2500(TM) Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	(2.51%)
5 YEARS	rr_AverageAnnualReturnYear05	1.24%
10 YEARS	rr_AverageAnnualReturnYear10	6.57%

[1] After-tax returns: - Are shown for Class A shares only and will vary for Class B, Class C and Advisor Class 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 fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

[2] 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.

[3] For Class C shares, the CDSC is 0% after the first year.

[4] Inception dates: 11/3/03 for Class R shares, and 3/1/05 for Class K and Class I shares. Performance information for periods prior to the inception of Class R, Class K and Class I shares is the performance of the Fund's Class A shares adjusted to reflect the higher expense ratio of Class R shares and the lower expense ratios of Class K and Class I shares, respectively.