| Label | Element | Value | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk/Return [Heading] | rr_RiskReturnHeading | AB Intermediate Diversified Municipal Portfolio of Sanford C. Bernstein Fund, Inc. | ||||||||||||||||
| Objective [Heading] | rr_ObjectiveHeading | INVESTMENT OBJECTIVE: | ||||||||||||||||
| Objective, Primary [Text Block] | rr_ObjectivePrimaryTextBlock | The investment objective of the Portfolio is to provide safety of principal and maximize total return after taking account of federal taxes.
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| Expense [Heading] | rr_ExpenseHeading | FEES AND EXPENSES OF THE PORTFOLIO: | ||||||||||||||||
| Expense Narrative [Text Block] | rr_ExpenseNarrativeTextBlock | This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Portfolio. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in any registered funds advised by AllianceBernstein L.P. More information about these and other discounts is available from your financial intermediary and in Investing in the Portfolios—Sales Charge Reduction Programs for Class A Shares, in Appendix B—Financial Intermediary Waivers on pages 80 and B-1, respectively, of the Portfolio’s Prospectus and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 82 of the Portfolio’s Statement of Additional Information (“SAI”).
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| Shareholder Fees Caption [Text] | rr_ShareholderFeesCaption | Shareholder Fees (fees paid directly from your investment) | ||||||||||||||||
| Operating Expenses Caption [Text] | rr_OperatingExpensesCaption | Annual Portfolio 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 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 Portfolio shares are held in a taxable account. These transaction costs, which are not reflected in the Annual Portfolio Operating Expenses or in the Examples, affect the Portfolio’s performance. During the most recent fiscal year, the Portfolio’s portfolio turnover rate was 24% of the average value of its portfolio.
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| Portfolio Turnover, Rate | rr_PortfolioTurnoverRate | 24.00% | ||||||||||||||||
| 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 (“CDSC”), which may be subject to waiver in certain circumstances.For Class C shares, the CDSC is 0% after the first year. Class C shares automatically convert to Class A shares after eight years. | ||||||||||||||||
| Expense Breakpoint Discounts [Text] | rr_ExpenseBreakpointDiscounts | You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in any registered funds advised by AllianceBernstein L.P. | ||||||||||||||||
| 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 Portfolio with the cost of investing in other mutual funds. The Examples assume that you invest $10,000 in the Portfolio 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 Portfolio’s operating expenses stay the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
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| Strategy [Heading] | rr_StrategyHeading | PRINCIPAL STRATEGIES: | ||||||||||||||||
| Strategy Narrative [Text Block] | rr_StrategyNarrativeTextBlock | As a matter of fundamental policy, the Portfolio, under normal circumstances, invests at least 80% of its net assets in municipal securities. For purposes of this policy, net assets include any borrowings for investment purposes. The Portfolio invests no more than 25% of its total assets in municipal securities of issuers located in any one state. The municipal securities in which the Portfolio may invest are issued to raise money for a variety of public or private purposes, including general financing for state and local governments, the District of Columbia or possessions and territories of the United States, or financing for specific projects or public facilities. The interest paid on these securities is generally exempt from federal income tax, although in certain instances, it may be includable in income subject to alternative minimum tax. The Portfolio invests at least 80% of its total assets in municipal securities rated A or better by NRSROs (or, if unrated, determined by AllianceBernstein L.P., the Portfolio’s investment manager (the “Manager”), to be of comparable quality) and comparably rated municipal notes. The Portfolio may invest up to 20% of its total assets in below investment grade fixed-income securities (commonly known as “junk bonds”). The Portfolio may invest, without limit, in revenue bonds, which generally do not have the pledge of the credit of the issuer. The Portfolio may invest, without limit, in securities or obligations that are related in such a way that business or political developments or changes affecting one such security could also affect the others (for example, securities with interest that is paid from projects of a similar type). The Portfolio may also invest up to 20% of its net assets in fixed-income securities of U.S. issuers that are not municipal securities if, in the Manager’s opinion, these securities will enhance the after-tax return for Portfolio investors. The Portfolio may use derivatives, such as options, futures contracts, forward contracts and swaps. In managing the Portfolio, the Manager may use interest rate forecasting to estimate an appropriate level of interest rate risk at a given time. The Portfolio seeks to maintain an effective duration of three and one-half years to seven years under normal market conditions. Duration is a measure that relates the expected price volatility of a security to changes in interest rates. The duration of a debt security is the weighted average term to maturity, expressed in years, of the present value of all future cash flows, including coupon payments and principal repayments. Within the range described above, the Manager may moderately shorten the average duration of the Portfolio when it expects interest rates to rise and moderately lengthen average duration when it anticipates that interest rates will fall. The Manager selects securities for purchase or sale based on its assessment of the securities’ risk and return characteristics as well as the securities’ impact on the overall risk and return characteristics of the Portfolio. In making this assessment, the Manager takes into account various factors including the credit quality and sensitivity to interest rates of the securities under consideration and of the Portfolio’s other holdings.
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| Risk [Heading] | rr_RiskHeading | PRINCIPAL RISKS: | ||||||||||||||||
| 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 Portfolio by showing:
You may obtain updated performance information on the website at www.abfunds.com (click on “Investments—Mutual Funds”). The Portfolio’s past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future. As with all investments, you may lose money by investing in the Portfolio.
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| Performance Information Illustrates Variability of Returns [Text] | rr_PerformanceInformationIllustratesVariabilityOfReturns | how the Portfolio’s performance changed from year to year over ten years; and how the Portfolio’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.abfunds.com | ||||||||||||||||
| Performance Past Does Not Indicate Future [Text] | rr_PerformancePastDoesNotIndicateFuture | The Portfolio’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 Portfolio’s Class A shares and do not reflect sales loads. If sales loads were reflected, returns would be less than those shown.
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| Bar Chart Does Not Reflect Sales Loads [Text] | rr_BarChartDoesNotReflectSalesLoads | The annual returns in the bar chart are for the Portfolio’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 Portfolio’s:Best Quarter was up 4.88%, 4th quarter, 2023; and Worst Quarter was down -4.49%, 1st quarter, 2022. | ||||||||||||||||
| Performance Table Heading | rr_PerformanceTableHeading | Performance Table Average Annual Total Returns* (For the periods ended December 31, 2023) | ||||||||||||||||
| Performance Table Does Reflect Sales Loads | rr_PerformanceTableDoesReflectSalesLoads | Average annual total returns reflect imposition of the maximum front-end or contingent deferred sales charges. | ||||||||||||||||
| Performance Table Uses Highest Federal Rate | rr_PerformanceTableUsesHighestFederalRate | After-tax returns:–Are an estimate, which is 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 Portfolio 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 Class C, Class Z and Advisor Class shares because these Classes have different expense ratios; | ||||||||||||||||
| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Risk Lose Money [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock | The share price of the Portfolio will fluctuate and you may lose money. | ||||||||||||||||
| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Interest Rate Risks [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Credit Risks [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Duration Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Municipal Market Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
In addition, changes in tax rates or the treatment of income from certain types of municipal securities, among other things, could negatively affect the municipal securities markets. The Portfolio may invest in municipal securities of issuers in Puerto Rico or other U.S. territories and their governmental agencies and municipalities, which are exempt from federal, state, and, where applicable, local income taxes. These municipal securities may have more risks than those of other U.S. issuers of municipal securities. Puerto Rico continues to face a very challenging economic and fiscal environment. If the general economic situation in Puerto Rico continues to persist or worsens, the volatility and credit quality of Puerto Rican municipal securities could continue to be adversely affected, and the market for such securities may deteriorate further.
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Inflation Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Illiquid Investments Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Redemption Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Derivatives Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
While hedging can guard against potential risks, there is also a risk that a derivative intended as a hedge may not perform as expected. In addition to other risks such as the credit risk of the counterparty (the party on the others side of the transaction), derivatives involve the risk that changes in the value of the derivative may not correlate with relevant assets, rates or indices. Derivatives may be difficult to price or unwind, and small changes may produce disproportionate losses for the Portfolio. Certain derivatives have the potential for unlimited loss, regardless of the size of the initial investment. Assets required to be set aside or posted as margin or collateral for derivatives positions may themselves go down in value, and these collateral and other requirements may limit investment flexibility. Some derivatives involve leverage, which can make the Portfolio more volatile and can compound other risks. Derivatives, especially over-the-counter derivatives, are also subject to counterparty risk, which is the risk that the counterparty on a derivative transaction will be unable or unwilling to honor its contractual obligations to the Portfolio. Use of derivatives may have different tax consequences for the Portfolio than an investment in the underlying asset or index, and such differences may affect the amount, timing and character of income distributed to shareholders, including the proportion of income consisting of exempt-interest dividends. The U.S. government and certain foreign governments have adopted regulations governing derivatives markets, including mandatory clearing of certain derivatives as well as additional regulations governing margin, reporting and registration requirements. The ultimate impact of the regulations remains unclear. Additional regulation may make derivatives more costly, limit their availability or utility, otherwise adversely affect their performance, or disrupt markets.
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Management Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Market Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
In addition, policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and these and other events affecting global markets, such as the United Kingdom’s exit from the European Union; potential trade imbalances with China or other countries; or sanctions or other government actions against Russia, other nations, or individuals or companies (or countermeasures taken in response to such sanctions), may contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the implications for market participants, may not be fully known for some time.
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Tax Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Lower rated Securities Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Prepayment and Extension Risk [Member] | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Risk [Text Block] | rr_RiskTextBlock |
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| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Class A | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | 3.00% | ||||||||||||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) | rr_MaximumDeferredSalesChargeOverOther | none | [1] | |||||||||||||||
| Management Fees | rr_ManagementFeesOverAssets | 0.36% | ||||||||||||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.25% | ||||||||||||||||
| Other Expenses: Transfer Agent | rr_Component2OtherExpensesOverAssets | 0.04% | ||||||||||||||||
| Other Expenses | rr_Component3OtherExpensesOverAssets | 0.04% | ||||||||||||||||
| Total Other Expenses | rr_OtherExpensesOverAssets | 0.08% | ||||||||||||||||
| Total Annual Portfolio Operating Expenses | rr_ExpensesOverAssets | 0.69% | ||||||||||||||||
| After 1 Year | rr_ExpenseExampleYear01 | $ 368 | ||||||||||||||||
| After 3 Years | rr_ExpenseExampleYear03 | 514 | ||||||||||||||||
| After 5 Years | rr_ExpenseExampleYear05 | 673 | ||||||||||||||||
| After 10 Years | rr_ExpenseExampleYear10 | $ 1,133 | ||||||||||||||||
| 2014 | rr_AnnualReturn2014 | 3.79% | ||||||||||||||||
| 2015 | rr_AnnualReturn2015 | 1.68% | ||||||||||||||||
| 2016 | rr_AnnualReturn2016 | (0.54%) | ||||||||||||||||
| 2017 | rr_AnnualReturn2017 | 2.74% | ||||||||||||||||
| 2018 | rr_AnnualReturn2018 | 0.65% | ||||||||||||||||
| 2019 | rr_AnnualReturn2019 | 5.47% | ||||||||||||||||
| 2020 | rr_AnnualReturn2020 | 3.92% | ||||||||||||||||
| 2021 | rr_AnnualReturn2021 | 1.18% | ||||||||||||||||
| 2022 | rr_AnnualReturn2022 | (5.94%) | ||||||||||||||||
| 2023 | rr_AnnualReturn2023 | 4.86% | ||||||||||||||||
| Highest Quarterly Return, Label | rr_HighestQuarterlyReturnLabel | Best Quarter | ||||||||||||||||
| Highest Quarterly Return, Date | rr_BarChartHighestQuarterlyReturnDate | Dec. 31, 2023 | ||||||||||||||||
| Highest Quarterly Return | rr_BarChartHighestQuarterlyReturn | 4.88% | ||||||||||||||||
| Lowest Quarterly Return, Label | rr_LowestQuarterlyReturnLabel | Worst Quarter | ||||||||||||||||
| Lowest Quarterly Return, Date | rr_BarChartLowestQuarterlyReturnDate | Mar. 31, 2022 | ||||||||||||||||
| Lowest Quarterly Return | rr_BarChartLowestQuarterlyReturn | (4.49%) | ||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 1.73% | [2],[3] | |||||||||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 1.19% | [2],[3] | |||||||||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.42% | [2],[3] | |||||||||||||||
| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | 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% | [4] | |||||||||||||||
| Management Fees | rr_ManagementFeesOverAssets | 0.36% | ||||||||||||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 1.00% | ||||||||||||||||
| Other Expenses: Transfer Agent | rr_Component2OtherExpensesOverAssets | 0.04% | ||||||||||||||||
| Other Expenses | rr_Component3OtherExpensesOverAssets | 0.04% | ||||||||||||||||
| Total Other Expenses | rr_OtherExpensesOverAssets | 0.08% | ||||||||||||||||
| Total Annual Portfolio Operating Expenses | rr_ExpensesOverAssets | 1.44% | ||||||||||||||||
| After 1 Year | rr_ExpenseExampleYear01 | $ 247 | [5] | |||||||||||||||
| After 3 Years | rr_ExpenseExampleYear03 | 456 | ||||||||||||||||
| After 5 Years | rr_ExpenseExampleYear05 | 787 | ||||||||||||||||
| After 10 Years | rr_ExpenseExampleYear10 | $ 1,520 | ||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 3.08% | [3] | |||||||||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 1.04% | [3] | |||||||||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 0.97% | [3] | |||||||||||||||
| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Class Z | ||||||||||||||||||
| 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 | ||||||||||||||||
| Management Fees | rr_ManagementFeesOverAssets | 0.36% | ||||||||||||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||||||||||
| Other Expenses: Transfer Agent | rr_Component2OtherExpensesOverAssets | 0.02% | ||||||||||||||||
| Other Expenses | rr_Component3OtherExpensesOverAssets | 0.03% | ||||||||||||||||
| Total Other Expenses | rr_OtherExpensesOverAssets | 0.05% | ||||||||||||||||
| Total Annual Portfolio Operating Expenses | rr_ExpensesOverAssets | 0.41% | ||||||||||||||||
| After 1 Year | rr_ExpenseExampleYear01 | $ 42 | ||||||||||||||||
| After 3 Years | rr_ExpenseExampleYear03 | 132 | ||||||||||||||||
| After 5 Years | rr_ExpenseExampleYear05 | 230 | ||||||||||||||||
| After 10 Years | rr_ExpenseExampleYear10 | $ 518 | ||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 5.16% | [3],[6] | |||||||||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 2.08% | [3],[6] | |||||||||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 2.05% | [3],[6] | |||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Jul. 02, 2018 | [3],[6] | |||||||||||||||
| AB Intermediate Municipal Portfolios | Diversified Municipal 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 | ||||||||||||||||
| Management Fees | rr_ManagementFeesOverAssets | 0.36% | ||||||||||||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||||||||||
| Other Expenses: Transfer Agent | rr_Component2OtherExpensesOverAssets | 0.04% | ||||||||||||||||
| Other Expenses | rr_Component3OtherExpensesOverAssets | 0.04% | ||||||||||||||||
| Total Other Expenses | rr_OtherExpensesOverAssets | 0.08% | ||||||||||||||||
| Total Annual Portfolio Operating Expenses | rr_ExpensesOverAssets | 0.44% | ||||||||||||||||
| After 1 Year | rr_ExpenseExampleYear01 | $ 45 | ||||||||||||||||
| After 3 Years | rr_ExpenseExampleYear03 | 141 | ||||||||||||||||
| After 5 Years | rr_ExpenseExampleYear05 | 246 | ||||||||||||||||
| After 10 Years | rr_ExpenseExampleYear10 | $ 555 | ||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 5.13% | [3],[7] | |||||||||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 2.07% | [3],[7] | |||||||||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.99% | [3],[7] | |||||||||||||||
| Inception Date | rr_AverageAnnualReturnInceptionDate | Jun. 26, 2015 | [3],[7] | |||||||||||||||
| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Return After Taxes on Distributions | Class A | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 1.66% | [2],[3] | |||||||||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 1.15% | [2],[3] | |||||||||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.39% | [2],[3] | |||||||||||||||
| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Return After Taxes on Distributions and Sale of Portfolio Shares | Class A | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 1.96% | [2],[3] | |||||||||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 1.35% | [2],[3] | |||||||||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.51% | [2],[3] | |||||||||||||||
| AB Intermediate Municipal Portfolios | Diversified Municipal Portfolio | Bloomberg 1-10 Year Blend Index (reflects no deduction for fees, expenses, or taxes) | ||||||||||||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||||||||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 4.61% | [3],[8] | |||||||||||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 1.96% | [3],[8] | |||||||||||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 2.19% | [3],[8] | |||||||||||||||
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