Label	Element	Value
AB All China Equity Portfolio
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	AB All China Equity Portfolio
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund’s investment objective is to seek 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 AB 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 69 of this Prospectus, in Appendix B—Financial Intermediary Waivers of this Prospectus and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 131 of the Fund’s Statement of Additional Information (“SAI”). You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Advisor Class shares, which are not reflected in the tables or the examples below.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	February 28, 2022
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 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 period, the Fund’s portfolio turnover rate was 74% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	74.00%
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 contingent deferred sales charge, or CDSC, which may be subject to waiver in certain circumstances.
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 AB 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 the periods. The Examples also assume that your investment has a 5% return each year, that the Fund’s operating expenses stay the same and that any fee waiver and/or expense limitation is in effect for only the first year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Adviser seeks to achieve the Fund’s investment objective by investing, under normal circumstances, at least 80% of the Fund’s net assets in a portfolio of equity securities of companies economically tied to the People’s Republic of China (“China”) (including Hong Kong). A company is considered to be economically tied to China if it: (i) is domiciled or organized in China; (ii) has securities that are traded principally in China; or (iii) conducts a substantial part of its economic activities in China. Equity securities may include common stocks, preferred stocks, the equity securities of real estate investment trusts, or REITs, depositary receipts and derivative instruments related to equity securities. The Adviser expects to invest Fund assets both in shares of companies that trade on the Shanghai Stock Exchange or the Shenzhen Stock Exchange (“China A shares”) and shares of companies economically tied to China that trade in Hong Kong or outside of China. The Adviser believes that, over time, securities that are undervalued by the market relative to their long-term earnings power can provide high returns. The Adviser utilizes fundamental analysis and its quantitative models to attempt to identify these securities for investment by the Fund, attempting to balance factors relating to valuation, company quality and investor sentiment, and will seek to build a portfolio that delivers attractive risk-adjusted returns. The Adviser may, but frequently will not, hedge the foreign currency exposure resulting from the Fund’s security positions through the use of currency-related derivatives. The Fund is “non-diversified”.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	• Market Risk: The value of the Fund’s assets will fluctuate as the stock market fluctuates. The value of its investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events, including public health crises (including the occurrence of a contagious disease or illness), 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 underperform the market generally. • 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 more difficult to trade due to adverse market, economic, political, regulatory or other factors. Investments in emerging market countries such as China may involve more risk than investments in developed countries because the markets in emerging market countries are less developed and less liquid and are subject to increased economic, political, regulatory, or other uncertainties. In addition, the value of the Fund’s investments may decline because of factors such as unfavorable or unsuccessful government actions and reduction in government or central bank support. • China/Single Country Risk: Investments in issuers located in a particular country or geographic region may have more risk because of particular market factors affecting that country or region, including political instability, geopolitical risks or unpredictable economic conditions. Risks of investments in securities of companies in China include the volatility of the Chinese stock market, heavy dependence on exports, which may be affected adversely by trade barriers or disputes or may decrease, sometimes significantly, when the world economy weakens, and the continuing importance of the role of the Chinese Government, which may take actions that affect economic and market practices. While the Chinese economy has grown at a rapid rate in recent years, the rate of growth has been declining, and there can be no assurance that China’s economy will continue to grow in the future. Investments in China A shares are subject to quotas that may restrict daily trading and to additional risks that could affect liquidity compared to investments in companies in developed markets. Risks of investments in companies based in Hong Kong include heavy reliance on the U.S. economy and regional economies, particularly the Chinese economy, which makes these investments vulnerable to changes in these economies. • Currency Risk: Fluctuations in currency exchange rates may negatively affect the value of the Fund’s investments in equity securities denominated in foreign currencies or reduce the Fund’s returns. Emerging market currencies may be more volatile and less liquid, and subject to significantly greater risk of currency controls and convertibility restrictions, than currencies of developed countries. • Depositary Receipts Risk: Investing in depositary receipts involves risks that are similar to the risks of direct investments in foreign securities. For example, investing in depositary receipts may involve risks relating to political, economic or regulatory conditions in foreign countries. In addition, the issuers of the securities underlying certain depositary receipts are under no obligation to distribute shareholder communications or pass through any voting rights with respect to the deposited securities to the holders of such receipts. • Illiquid Investments Risk: Illiquid investments risk exists when certain investments are or become difficult to purchase or sell. Difficulty in selling such investments may result in sales at disadvantageous prices affecting the value of your investment in the Fund. Causes of illiquid investments risk may include low trading volumes and large positions. Foreign fixed-income securities may have more illiquid investments risk because secondary trading markets for these securities may be smaller and less well-developed and the securities may trade less frequently. Illiquid investments risk may be higher in a rising interest rate environment, when the value and liquidity of fixed-income securities generally go down. • Non-Diversification Risk: The Fund may have more risk because it is “non-diversified”, meaning that it can invest more of its assets in a smaller number of issuers. Accordingly, changes in the value of a single security may have a more significant effect, either negative or positive, on the Fund’s net asset value, or NAV. • Industry/Sector Risk: Investments in a particular industry or group of related industries may have more risk because market or economic factors affecting that industry could have a significant effect on the value of the Fund’s 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, but there is no guarantee that its techniques will produce the intended results. Some of these techniques may incorporate, or rely upon, quantitative models, but there is no guarantee that these models will generate accurate forecasts, reduce risk or otherwise perform as expected. 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.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Non-Diversification Risk: The Fund may have more risk because it is “non-diversified”, meaning that it can invest more of its assets in a smaller number of issuers. Accordingly, changes in the value of a single security may have a more significant effect, either negative or positive, on the Fund’s net asset value, or NAV.
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 year and since inception compare to those of a broad-based securities market index. You may obtain updated performance information on the Fund’s website at www.abfunds.com (click on “Investments—Mutual Funds”). 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 year and since inception compare to those of a broad-based securities market index.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.abfunds.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.
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. If sales loads were reflected, returns would be less than those shown.
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 27.93%, 1st quarter, 2019; and Worst Quarter was down -11.64%, 1st quarter, 2020.
Performance Table Heading	rr_PerformanceTableHeading	Performance Table Average Annual Total Returns (For the periods ended December 31, 2020)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns: – 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	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.
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;
AB All China Equity Portfolio | 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_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.95%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.02%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.34%
Total Other Expenses	rr_OtherExpensesOverAssets	0.36%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.56%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.06%)	[2]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.50%
After 1 Year	rr_ExpenseExampleYear01	$ 571
After 3 Years	rr_ExpenseExampleYear03	891
After 5 Years	rr_ExpenseExampleYear05	1,233
After 10 Years	rr_ExpenseExampleYear10	$ 2,198
2011	rr_AnnualReturn2011
2012	rr_AnnualReturn2012
2013	rr_AnnualReturn2013
2014	rr_AnnualReturn2014
2015	rr_AnnualReturn2015
2016	rr_AnnualReturn2016
2017	rr_AnnualReturn2017
2018	rr_AnnualReturn2018
2019	rr_AnnualReturn2019	37.12%
2020	rr_AnnualReturn2020	25.07%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2019
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	27.93%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2020
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(11.64%)
1 Year	rr_AverageAnnualReturnYear01	19.79%	[3]
Since Inception	rr_AverageAnnualReturnSinceInception	10.95%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 25, 2018	[3]
AB All China Equity Portfolio | 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_ExchangeFeeOverRedemption	none
Management Fees	rr_ManagementFeesOverAssets	0.95%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.02%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.34%
Total Other Expenses	rr_OtherExpensesOverAssets	0.36%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.31%
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.06%)	[2]
Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement	rr_NetExpensesOverAssets	1.25%
After 1 Year	rr_ExpenseExampleYear01	$ 127
After 3 Years	rr_ExpenseExampleYear03	409
After 5 Years	rr_ExpenseExampleYear05	712
After 10 Years	rr_ExpenseExampleYear10	$ 1,574
1 Year	rr_AverageAnnualReturnYear01	25.39%
Since Inception	rr_AverageAnnualReturnSinceInception	13.23%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 25, 2018
AB All China Equity Portfolio | Return After Taxes on Distributions | Class A
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	19.82%	[3]
Since Inception	rr_AverageAnnualReturnSinceInception	10.85%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 25, 2018	[3]
AB All China Equity Portfolio | Return After Taxes on Distributions and Sale of Fund Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	11.86%	[3]
Since Inception	rr_AverageAnnualReturnSinceInception	8.50%	[3],[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 25, 2018	[3]
AB All China Equity Portfolio | MSCI China All Shares Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	33.41%
Since Inception	rr_AverageAnnualReturnSinceInception	14.90%	[4]

[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 contingent deferred sales charge, or CDSC, which may be subject to waiver in certain circumstances.

[2] The Adviser has contractually agreed to waive its management fee and/or to bear certain expenses of the Fund until February 28, 2022 to the extent necessary to prevent total Fund operating expenses (excluding acquired fund fees and expenses other than the advisory fees of any AB Mutual Funds in which the Fund may invest, interest expense, taxes, extraordinary expenses, and brokerage commissions and other transaction costs), on an annualized basis, from exceeding 1.50% and 1.25% of average daily net assets, respectively, for Class A and Advisor Class shares (“expense limitations”). Any fees waived and expenses borne by the Adviser may be reimbursed by the Fund until the end of the third fiscal year after the fiscal period in which the fee was waived or the expense was borne, provided that no reimbursement payment will be made that would cause the Fund’s covered operating expenses to exceed the applicable expense limitations. In connection with the Fund’s investments in AB Government Money Market Portfolio (the “Money Market Portfolio”) (except for the investment of any cash collateral from securities lending), the Adviser has contractually agreed to waive its management fee from the Fund and/or reimburse other expenses of the Fund in an amount equal to the Fund’s pro rata share of the Money Market Portfolio’s effective management fee. Each of the agreements will remain in effect until February 28, 2022 and may only be terminated or changed with the consent of the Fund’s Board of Directors. In addition, each of the agreements will be automatically extended for one-year terms unless the Adviser provides notice of termination to the Fund at least 60 days prior to the end of the period.

[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 fund shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

[4] Inception date for all Classes is 7/25/18.