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Short Duration Diversified Municipal Portfolio  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading FIXED-INCOME MUNICIPAL PORTFOLIOS Short Duration Portfolio Short Duration Diversified Municipal Portfolio of Sanford C. Bernstein Fund, Inc.
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE:
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Portfolio’s investment objective is to provide safety of principal and a moderate rate of return after taking account of federal taxes.
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.
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 40% of the average value of its portfolio. 
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 40.00%
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 as reflected in the Examples would be:
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 any nationally recognized statistical rating organization (“NRSRO”) (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 one‑half year to two and one‑half 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.
Risk [Heading] rr_RiskHeading PRINCIPAL RISKS:
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
The share price of the Portfolio will fluctuate and you may lose money. There is no guarantee that the Portfolio will achieve its investment objective.
  
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Interest Rate Risk: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of existing 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. During periods of very low or negative interest rates, the Portfolio’s returns may be adversely affected, including to such an extent that the Portfolio may be unable to maintain positive returns. A Portfolio may be subject to a greater risk of rising interest rates than would normally be the case due to the recent tightening of the U.S. Federal Reserve’s monetary policy, which has caused the Federal Reserve to increase short-term interest rates in an effort to address rising inflation. 
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Credit Risk: This is the risk that the issuer or the guarantor of a debt security, or the counterparty to a derivatives or other contract, will be unable or unwilling to make timely principal and/or interest payments, or to otherwise honor its obligations. The issuer or guarantor may default, potentially causing a loss of the full principal amount of a security and accrued interest. The 
 
degree of risk for a particular security may be reflected in its credit rating, although credit ratings are opinions and not guarantees of quality. 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 tend to have a higher probability that an issuer will default or fail to meet its payment obligations, making credit risk greater for medium-quality and lower-rated debt securities. Lower-rated debt securities and similar unrated securities (commonly known as “junk bonds”) have speculative elements or are predominantly speculative credit risks. At times when credit risk is perceived to be greater, credit “spreads” (i.e., the difference between the yields on lower quality securities and the yields on higher quality securities) may get larger or “widen”. As a result, the values of the lower quality securities may go down more and they may become harder to sell. 
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Duration Risk: The duration of a fixed-income security may be shorter than or equal to full maturity of the fixed-income security. Fixed-income securities with longer durations have more interest rate risk and will decrease in price as interest rates rise. Securities that have final maturities longer than their durations may be affected by increased credit spreads to a far greater degree than their durations would suggest, because they are exposed to credit risk until final maturity. 
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Municipal Market Risk: This is the risk that special factors may adversely affect the value of municipal securities and have a significant effect on the yield or value of the Portfolio’s investments in municipal securities. These factors include economic conditions, political or legislative changes, uncertainties related to the tax status of municipal securities, and the rights of investors in these securities. The value of municipal securities may also be adversely affected by rising health care costs, increasing unfunded pension liabilities, and by the phasing out of federal programs providing financial support. There have been some municipal issuers that have defaulted on obligations, been downgraded or commenced insolvency proceedings. Financial difficulties of municipal issuers may get worse, particularly in light of the economic impact of the recent spread of an infectious coronavirus (COVID‑19). To the extent the Portfolio invests in a particular state’s municipal securities, it may be vulnerable to events adversely affecting that state, including economic, political and regulatory occurrences, court decisions, terrorism, public health crises (including the occurrence of a contagious disease or illness) and catastrophic natural disasters, such as hurricanes, wildfires, flooding and earthquakes, which may be further exacerbated by recent environmental conditions and climate change patterns. The Portfolio’s investments in certain municipal securities with principal and interest payments that are made from the revenues of a specific project or facility, and not general tax revenues, are subject to the risk that factors affecting the project or facility, such as local business or economic conditions, could have a significant effect on the project’s ability to make payments of principal and interest on these securities. 
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, worsened by the spread of COVID‑19 and the adverse effect that related governmental and public responses have had on Puerto Rico’s economy. 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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Inflation Risk: This is the risk that the value of assets or income from investments will be less in the future as inflation decreases the value of money. As inflation increases, the value of the Portfolio’s assets can decline as can the value of the Portfolio’s distributions. This risk is significantly greater for fixed-income securities with longer maturities. Rates of inflation have recently risen, which have adversely affected economies and markets. Rising inflation has caused the Federal Reserve and other central banks to take actions—including raising interest rates—that have caused further adverse effects to economies and markets, and more such actions may be forthcoming. 
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Illiquid Investments Risk: Illiquid investments risk exists when particular investments are difficult or impossible to purchase or sell, possibly preventing the Portfolio from purchasing or selling these securities at an advantageous price. In certain cases, governmental actions could prevent sales of securities or repatriation of proceeds. Over recent years, regulatory changes have led to reduced liquidity in the marketplace, and the capacity of dealers to make markets in fixed-income securities has been outpaced by the growth in the size of the fixed-income markets. Illiquid investments risk may be magnified in a rising interest rate environment, where the value and liquidity of fixed-income securities generally go down. The Portfolio is subject to greater risk because the market for municipal securities is generally smaller and may not be as liquid as many other fixed-income markets, which may make municipal securities more difficult to trade or dispose of than other types of securities. Illiquid securities may also be difficult to value. If the Portfolio is forced to sell an illiquid asset to meet redemption requests or other cash needs, or to try to limit losses, the Portfolio may be forced to sell at a substantial loss or may not be able to sell at all. 
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Redemption Risk: The Portfolio may experience heavy redemptions that could cause the Portfolio to liquidate its assets at inopportune times or unfavorable prices or increase or accelerate taxable gains or transaction costs and may negatively affect the Portfolio’s net asset value, or performance, which could cause the value of your investment to decline. Redemption risk is heightened during periods of overall market turmoil. 
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Derivatives Risk: The Portfolio may use derivatives as direct investments to earn income, enhance return and broaden portfolio diversification, which entail greater risk than if used solely for hedging purposes. 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, 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 (the party on the other side of the transaction) 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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Management Risk: The Portfolio is subject to management risk because it is an actively-managed investment portfolio. The Manager will apply its investment techniques and risk analyses in making investment decisions for the Portfolio, but these techniques, analyses and decisions may not work as intended or may not produce the desired results, and may, during certain periods, result in increased volatility for the Portfolio or cause the value of the Portfolio’s shares to go down. In some cases, derivatives and other investment techniques may be unavailable, or the Manager may determine not to use them, possibly even under market conditions where their use could benefit the Portfolio. 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. In addition, the Manager may change the Portfolio’s investment strategies or policies from time to time. Those changes may not lead to the results intended by the Manager and could have an adverse effect on the value or performance of the Portfolio. 
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Market Risk: The Portfolio is subject to market risk, which is the risk that bond prices in general or in particular countries or sectors may decline over short or extended periods. In the past decade, financial markets in the United States and elsewhere have experienced increased volatility, decreased liquidity and heightened uncertainty. These market conditions may continue, worsen, or spread. Governmental and quasi-governmental authorities and regulators throughout the world have provided significant support to financial markets in response to serious economic disruptions, including, but not limited to, buying stocks, providing direct capital infusions into companies, implementing new monetary programs, dramatically lowering interest rates and through other market interventions. Government actions to support the economy and financial markets have resulted in a large expansion of government deficits and debt, the long term consequences of which are not known. Rates of inflation have recently risen. The Federal Reserve, as well as certain foreign central banks have recently raised interest rates as part of their efforts to address rising inflation, and there is a risk that interest rates will continue to rise. Central bank, government or regulatory actions, including increases or decreases in interest rates, or actions that are inconsistent with such actions by different central banks, governments or regulators, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the Portfolio invests. From time to time, uncertainty regarding the status of negotiations in the U.S. government to increase the statutory debt ceiling could: increase the risk that the U.S. government may default on payments on certain U.S. government securities; cause the credit rating of the U.S. government to be downgraded or increase volatility in both stock and bond markets; result in higher interest rates; reduce prices of U.S. Treasury securities; and/or increase the costs of certain kinds of debt. 
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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Tax Risk: There is no guarantee that the income on the Portfolio’s municipal securities will be exempt from regular federal income, and if applicable, state income taxes. Unfavorable legislation, adverse interpretations by federal or state authorities, litigation or noncompliant conduct by the issuer of a municipal security could affect the tax‑exempt status of municipal securities. If the Internal Revenue Service or a state authority determines that an issuer of a municipal security has not complied with applicable requirements, interest from the security could become subject to regular federal income tax and/or state personal income tax, possibly retroactively to the date the security was issued, the value of the security could decline significantly, and a portion of the distributions to Portfolio shareholders could be recharacterized as taxable. From time to time, the U.S. Government and 
 
the U.S. Congress consider changes in federal tax law that would, if enacted, have a negative impact on certain types of municipal securities, such as private activity bonds, or would otherwise make investments in municipal bonds less attractive. 
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Lower-rated Securities Risk: Lower-rated securities, or junk bonds/high-yield securities, are subject to greater risk of loss of principal and interest and greater market risk than higher-rated securities. The capacity of issuers of lower-rated securities to pay interest and repay principal is more likely to weaken than is that of issuers of higher-rated securities in times of deteriorating economic conditions or rising interest rates. 
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Prepayment and Extension Risk: Prepayment risk is the risk that a loan, bond or other security might be called or otherwise converted, prepaid or redeemed before maturity. If this happens, particularly during a time of declining interest rates or credit spreads, the Portfolio will not benefit from the rise in market price that normally accompanies a decline in interest rates, and may not be able to invest the proceeds in securities providing as much income, resulting in a lower yield to the Portfolio. Conversely, extension risk is the risk that as interest rates rise or spreads widen, payments of securities may occur more slowly than anticipated by the market. If this happens, the values of these securities may go down because their interest rates are lower than current market rates and they remain outstanding longer than anticipated. 
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Riskier than a Money-Market Fund: Although the Portfolio maintains a short overall duration, it invests in securities with longer maturities and in some cases lower quality than the assets of the type of mutual fund known as a money-market fund. The risk of a decline in the market value of the Portfolio is greater than for a money-market fund since the credit quality of the Portfolio’s securities may be lower and the effective duration of the Portfolio will be longer. 
Risk Lose Money [Text] rr_RiskLoseMoney The share price of the Portfolio will fluctuate and you may lose money.
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:
  
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how the Portfolio’s performance changed from year to year over ten years; and
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how the Portfolio’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 for the Portfolio at www.bernstein.com (at the bottom of the page, click on “Investments,” then “Mutual Fund Performance at a Glance”). 
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. 
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns how the Portfolio’s performance changed from year to year over ten years; andhow 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.bernstein.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 Short Duration Diversified Municipal Class shares.
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 1.88%, 2nd quarter, 2020; and Worst Quarter was down -2.60%, 1st quarter, 2022.
Performance Table Heading rr_PerformanceTableHeading Performance Table Average Annual Total Returns(For the periods ended December 31, 2022)
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 Narrative rr_PerformanceTableNarrativeTextBlock
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; 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.
Short Duration Diversified Municipal Portfolio | Short Duration Diversified Municipal 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
Maximum Account Fee rr_MaximumAccountFeeOverAssets none
Management Fees rr_ManagementFeesOverAssets 0.30%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses: Shareholder Servicing rr_Component1OtherExpensesOverAssets 0.10%
Other Expenses: Transfer Agent rr_Component2OtherExpensesOverAssets 0.01%
Other Expenses rr_Component3OtherExpensesOverAssets 0.06%
Total Other Expenses rr_OtherExpensesOverAssets 0.17%
Total Annual Portfolio Operating Expenses rr_ExpensesOverAssets 0.47%
After 1 Year rr_ExpenseExampleYear01 $ 48
After 3 Years rr_ExpenseExampleYear03 151
After 5 Years rr_ExpenseExampleYear05 263
After 10 Years rr_ExpenseExampleYear10 $ 591
2013 rr_AnnualReturn2013 0.44%
2014 rr_AnnualReturn2014 0.12%
2015 rr_AnnualReturn2015 0.30%
2016 rr_AnnualReturn2016 (0.03%)
2017 rr_AnnualReturn2017 0.75%
2018 rr_AnnualReturn2018 1.13%
2019 rr_AnnualReturn2019 2.32%
2020 rr_AnnualReturn2020 2.30%
2021 rr_AnnualReturn2021 0.33%
2022 rr_AnnualReturn2022 (2.87%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 1.88%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (2.60%)
1 Year rr_AverageAnnualReturnYear01 (2.87%)
5 Years rr_AverageAnnualReturnYear05 0.62%
10 Years rr_AverageAnnualReturnYear10 0.47%
Short Duration Diversified Municipal Portfolio | Return After Taxes on Distributions | Short Duration Diversified Municipal Class  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 (2.91%)
5 Years rr_AverageAnnualReturnYear05 0.60%
10 Years rr_AverageAnnualReturnYear10 0.44%
Short Duration Diversified Municipal Portfolio | Return After Taxes on Distributions and Sale of Portfolio Shares | Short Duration Diversified Municipal Class  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 (1.34%)
5 Years rr_AverageAnnualReturnYear05 0.70%
10 Years rr_AverageAnnualReturnYear10 0.51%
Short Duration Diversified Municipal Portfolio | Bloomberg 1-Year Municipal Index (reflects no deduction for fees, expenses, or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 (1.13%)
5 Years rr_AverageAnnualReturnYear05 1.02%
10 Years rr_AverageAnnualReturnYear10 0.83%