485BPOS

As filed with the Securities and Exchange Commission on February 21, 2013

File Nos. 33-07812

811-04791

SECURITIES AND EXCHANGE COMMISSION

Washington,  D.C.  20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933	¨
Pre-Effective Amendment No.	¨
Post-Effective Amendment No. 50	x

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940

Amendment No. 52 x

ALLIANCEBERNSTEIN MUNICIPAL INCOME FUND, INC.

(Exact Name of Registrant as Specified in Charter)

1345 Avenue of the Americas,

New York, New York 10105

(Address of Principal Executive Office) (Zip Code)

Registrant’s Telephone Number, including Area Code:

(800) 221-5672

EMILIE D. WRAPP

AllianceBernstein L.P.

1345 Avenue of the Americas

New York, New York 10105

(Name and address of agent for service)

Copies of communications to:

Kathleen K. Clarke

Seward & Kissel LLP

901 K Street, N.W.

Suite 800

Washington, DC 20001

It is proposed that this filing will become effective (check appropriate box)

¨ immediately upon filing pursuant to paragraph (b)

x on February 21, 2013 pursuant to paragraph (b)

¨ 60 days after filing pursuant to paragraph (a)

¨ on (date) pursuant to paragraph (a)

¨ 75 days after filing pursuant to paragraph (a)(2)

¨ on (date) pursuant to paragraph (a)(2) of Rule 485

If appropriate, check the following box:

¨ This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Amendment to its Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Amendment to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of New York and the State of New York, on the 21st day of February, 2013.

ALLIANCEBERNSTEIN MUNICIPAL INCOME FUND, INC.
By:	Robert M. Keith*
	Robert M. Keith
	President

Pursuant to the requirements of the Securities Act of l933, this Post-Effective Amendment to the Registration Statement has been signed below by the following persons in the capacities and on the dates indicated:

	Signature	Title	Date
(1)	Principal Executive Officer:
	Robert M. Keith* Robert M. Keith	President and Chief Executive Officer	February 21, 2013
(2)	Principal Financial and Accounting Officer:
	/s/    Joseph J. Mantineo Joseph J. Mantineo	Treasurer and Chief Financial Officer	February 21, 2013
(3)	Directors:
	John H. Dobkin* Michael J. Downey* William H. Foulk, Jr.* D. James Guzy* Nancy P. Jacklin* Robert M. Keith* Garry L. Moody* Marshall C. Turner, Jr.* Earl D. Weiner*
*By	/s/    Emilie D. Wrapp Emilie D. Wrapp (Attorney-in-fact)		February 21, 2013

Index to Exhibits

Exhibit No.	Description of Exhibits
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CALC	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	ALLIANCEBERNSTEIN MUNICIPAL INCOME FUND INC
Prospectus Date	rr_ProspectusDate	Jan. 31, 2013
Document Creation Date	dei_DocumentCreationDate	Jan. 31, 2013

XML

New York Portfolio

NEW YORK PORTFOLIO

INVESTMENT OBJECTIVE:

The investment objective of the Portfolio is to earn the highest level of current income exempt from both federal income tax and New York State and City income tax that is available without assuming what the Adviser considers to be undue risk to principal or income.

FEES AND EXPENSES OF THE PORTFOLIO:

This table describes the fees and expenses that you may pay if you buy and hold shares of the Portfolio. 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 Portfolios—Sales Charge Reduction Programs for Class A Shares on page 75 of this Prospectus, and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 149 of the Portfolio's SAI.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees New York Portfolio (USD $)	CLASS A SHARES	CLASS B SHARES		CLASS C SHARES		ADVISOR CLASS SHARES
Shareholder Fees Column [Text]		(not currently offered to new investors)
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	3.00%	none		none		none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	none	3.00%	[1]	1.00%	[2]	none
Exchange Fee	none	none		none		none

Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Portfolio Operating Expenses New York Portfolio		CLASS A	CLASS B	CLASS C	ADVISOR CLASS
Management Fees		0.45%	0.45%	0.45%	0.45%
Distribution and/or Service (12b-1) Fees		0.30%	1.00%	1.00%	none
Other Expenses: Transfer Agent		0.03%	0.05%	0.04%	0.03%
Other Expenses		0.07%	0.07%	0.06%	0.06%
Total Other Expenses		0.10%	0.12%	0.10%	0.09%
Total Annual Portfolio Operating Expenses	[1]	0.85%	1.57%	1.55%	0.54%
Fee Waiver and/or Expense Reimbursement	[2][3]	(0.05%)	(0.07%)	(0.05%)	(0.04%)
Total Annual Portfolio Operating Expenses	[3][4]	0.80%	1.50%	1.50%	0.50%

Examples

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, that the Portfolio's operating expenses stay the same and that the fee waiver remains in effect for only one year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example New York Portfolio (USD $)	CLASS A	CLASS B	CLASS C	ADVISOR CLASS
After 1 Year	379	453	253	51
After 3 Years	558	589	485	169
After 5 Years	752	849	840	298
After 10 Years	1,313	1,490	1,841	673

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:

Expense Example, No Redemption New York Portfolio (USD $)	CLASS B	CLASS C
After 1 Year	153	153
After 3 Years	489	485
After 5 Years	849	840
After 10 Years	1,490	1,841

Portfolio Turnover

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 14% of the average value of its portfolio.

PRINCIPAL STRATEGIES:

The Portfolio pursues its objective by investing principally in high-yielding, predominantly investment grade municipal securities. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities that pay interest that is exempt from federal income tax. These securities may pay interest that is subject to the federal AMT for certain taxpayers. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities of New York or municipal securities with interest that is otherwise exempt from New York state income tax.

The Portfolio may also invest in:

• forward commitments;

• zero-coupon municipal securities and variable, floating and inverse floating rate municipal securities; and

• derivatives, such as options, futures, forwards and swaps.

PRINCIPAL RISKS:

• MARKET RISK: The value of the Portfolio's assets will fluctuate as the bond market fluctuates. The value of the Portfolio's investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market.

• CREDIT RISK: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security. Investments in fixed-income securities with lower ratings tend to have a higher probability that an issuer will default or fail to meet its payment obligations.

• 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, or the rights of investors in these securities. The Portfolio's investments in New York municipal securities may be vulnerable to events adversely affecting its economy. New York's economy, while diverse, has a relatively large share of the nation's financial activities. With the financial services sector contributing over one-fifth of the state's wages, the state's economy is especially vulnerable to adverse events affecting the financial markets such as occurred in 2008-2009. 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, may have increased risks. 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.

• TAX RISK: There is no guarantee that all of the Portfolio's income will remain exempt from federal or state income taxes. From time to time, the U.S. Government and the U.S. Congress consider changes in federal tax law that could limit or eliminate the federal tax exemption for municipal bond income, which would in effect reduce the income received by shareholders from the Portfolio by increasing taxes on that income. In such event, the Portfolio's NAV could also decline as yields on municipal bonds, which are typically lower than those on taxable bonds, would be expected to increase to approximately the yield of comparable taxable bonds. Actions or anticipated actions affecting the tax exempt status of municipal bonds could also result in significant shareholder redemptions of Portfolio shares as investors anticipate adverse effects on the Portfolio or seek higher yields to offset the potential loss of the tax deduction. As a result, the Portfolio would be required to maintain higher levels of cash to meet the redemptions, which would negatively affect the Portfolio's yield.

• INTEREST RATE RISK: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest rate risk is generally greater for fixed-income securities with longer maturities or durations.

• DURATION RISK: Duration is a measure that relates the expected price volatility of a fixed-income security to changes in interest rates. The duration of a fixed-income security may be shorter than or equal to full maturity of a fixed-income security. Fixed–income securities with longer durations have more risk and will decrease in price as interest rates rise. For example, a fixed–income security with a duration of three years will decrease in value by approximately 3% if interest rates increase by 1%.

• 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.

• LIQUIDITY RISK: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Portfolio from selling out of these illiquid securities at an advantageous price. Derivatives and securities involving substantial market and credit risk tend to involve greater liquidity risk. The Portfolio is subject to liquidity risk because the market for municipal securities is generally smaller than many other markets.

• DERIVATIVES RISK: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Portfolio, and may be subject to counterparty risk to a greater degree than more traditional investments.

• MANAGEMENT RISK: The Portfolio 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.

As with all investments, you may lose money by investing in the Portfolio.

BAR CHART AND PERFORMANCE INFORMATION:

The bar chart and performance information provide an indication of the historical risk of an investment in the Portfolio by showing:

• 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.

You may obtain updated performance information on the Portfolio's website at www.AllianceBernstein.com (click on "Individuals-U.S." then "Products & Performance").

The Portfolio's past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future.

Bar Chart

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.

Calendar Year End (%)

During the period shown in the bar chart, the Portfolio's:

BEST QUARTER WAS UP 6.36%, 3RD QUARTER , 2009; AND WORST QUARTER WAS DOWN -3.73%, 4TH QUARTER, 2010.

Performance Table
Average Annual Total Returns
(For the periods ended December 31, 2012)

Average Annual Total Returns New York Portfolio		1 YEAR		5 YEARS		10 YEARS		INCEPTION DATE
CLASS A	[1]	3.25%		4.58%		4.60%
CLASS A Return After Taxes on Distributions	[1]	3.21%		4.56%		4.59%
CLASS A Return After Taxes on Distributions and Sale of Portfolio Shares	[1]	3.34%		4.45%		4.53%
CLASS B		2.68%		4.49%		4.48%
CLASS C		4.77%		4.50%		4.20%
ADVISOR CLASS		6.73%	[2]	5.53%	[2]	5.23%	[2]	Aug. 06, 2008
Barclays Municipal Bond Index (reflects no deduction for fees, expenses or taxes)		6.78%		5.91%		5.10%

[1] Class B shares automatically convert to Class A shares after six years. The CDSC decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the third year.

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

[1] Before Waiver

[2] The fee waiver and/or expense reimbursement agreement will remain in effect until January 31, 2014 and will be automatically extended for one-year terms thereafter unless terminated by the Adviser upon 60 days' notice to the Portfolio prior to that date.

[3] Restated to reflect current fee waiver and/or expense reimbursement.

[4] After Fee Waiver and/or Expense Reimbursement

[1] After-tax Returns: - Are shown for Class A shares only and will vary for Class B and C shares because these Classes have higher expense ratios; - 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.

[2] Inception date for Advisor Class shares: 8/6/08. Performance information for periods prior to the inception of Advisor Class shares is the performance of the Portfolio's Class A shares adjusted to reflect the lower expense ratio of Advisor Class shares.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	ALLIANCEBERNSTEIN MUNICIPAL INCOME FUND INC
Prospectus Date	rr_ProspectusDate	Jan. 31, 2013
National Portfolio
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	National Portfolio
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE:
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of the Portfolio is to earn the highest level of current income, exempt from federal income tax, that is available without assuming what the Adviser considers to be undue risk to principal or income.
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 and hold shares of the Portfolio. 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 Portfolios—Sales Charge Reduction Programs for Class A Shares on page 75 of this Prospectus and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 149 of the Portfolio's Statement of Additional Information ("SAI").
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)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
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 11% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	11.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	Class B shares automatically convert to Class A shares after six years. The contingent deferred sales charge, or CDSC, decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the third year. For Class C shares, the CDSC is 0% after the first year.
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AllianceBernstein Mutual Funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	100,000
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	Restated to reflect current fee waiver and/or expense reimbursement.
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 and that the fee waiver remains in effect for only one year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	For the share classes listed below, you would pay the following expenses if you did not redeem your shares at the end of the period:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL STRATEGIES:
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Portfolio pursues its objective by investing principally in high-yielding, predominantly investment grade municipal securities. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities that pay interest that is exempt from federal income tax. These securities may pay interest that is subject to the federal alternative minimum tax ("AMT") for certain taxpayers. The Portfolio may invest more than 25% of its assets in a single state. The Portfolio may also invest in: forward commitments; tender option bonds ("TOBs"); zero-coupon municipal securities and variable, floating and inverse floating rate municipal securities; and derivatives, such as options, futures, forwards and swaps.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS:
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	MARKET RISK: The value of the Portfolio's assets will fluctuate as the bond market fluctuates. The value of the Portfolio's investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market. CREDIT RISK: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security. Investments in fixed-income securities with lower ratings tend to have a higher probability that an issuer will default or fail to meet its payment obligations. 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, or the rights of investors in these securities. To the extent that the Portfolio invests more of its assets in a particular state's municipal securities, the Portfolio may be vulnerable to events adversely affecting that state, including economic, political and regulatory occurrences, court decisions, terrorism and catastrophic natural disasters, such as hurricanes or earthquakes. 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, may have increased risks. 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. TAX RISK: There is no guarantee that all of the Portfolio's income will remain exempt from federal or state income taxes. From time to time, the U.S. Government and the U.S. Congress consider changes in federal tax law that could limit or eliminate the federal tax exemption for municipal bond income, which would in effect reduce the income received by shareholders from the Portfolio by increasing taxes on that income. In such event, the Portfolio's net asset value, or NAV, could also decline as yields on municipal bonds, which are typically lower than those on taxable bonds, would be expected to increase to approximately the yield of comparable taxable bonds. Actions or anticipated actions affecting the tax exempt status of municipal bonds could also result in significant shareholder redemptions of Portfolio shares as investors anticipate adverse effects on the Portfolio or seek higher yields to offset the potential loss of the tax deduction. As a result, the Portfolio would be required to maintain higher levels of cash to meet the redemptions, which would negatively affect the Portfolio's yield. INTEREST RATE RISK: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest rate risk is generally greater for fixed-income securities with longer maturities or durations. DURATION RISK: Duration is a measure that relates the expected price volatility of a fixed-income security to changes in interest rates. The duration of a fixed-income security may be shorter than or equal to full maturity of a fixed-income security. Fixed-income securities with longer durations have more risk and will decrease in price as interest rates rise. For example, a fixed-income security with a duration of three years will decrease in value by approximately 3% if interest rates increase by 1%. 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. LIQUIDITY RISK: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Portfolio from selling out of these illiquid securities at an advantageous price. Derivatives and securities involving substantial market and credit risk tend to involve greater liquidity risk. The Portfolio is subject to liquidity risk because the market for municipal securities is generally smaller than many other markets. DERIVATIVES RISK: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Portfolio, and may be subject to counterparty risk to a greater degree than more traditional investments. MANAGEMENT RISK: The Portfolio 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. As with all investments, you may lose money by investing in the Portfolio.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with all investments, you may lose money by investing in the Portfolio.
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: 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. You may obtain updated performance information on the Portfolio's website at www.AllianceBernstein.com (click on "Individuals—U.S." then "Products & Performance"). The Portfolio'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 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.AllianceBernstein.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.
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 7.66%, 3RD QUARTER, 2009; AND WORST QUARTER WAS DOWN -4.69%, 4TH QUARTER, 2008.
Performance Table Heading	rr_PerformanceTableHeading	Performance Table Average Annual Total Returns (For the periods ended December 31, 2012)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	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	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 B and C shares because these Classes have higher expense ratios;
National 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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.30%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.04%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.01%
Total Other Expenses	rr_OtherExpensesOverAssets	0.11%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	0.86%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	0.81%	[3],[4],[5]
After 1 Year	rr_ExpenseExampleYear01	380
After 3 Years	rr_ExpenseExampleYear03	561
After 5 Years	rr_ExpenseExampleYear05	758
After 10 Years	rr_ExpenseExampleYear10	1,324
03	rr_AnnualReturn2003	7.41%
04	rr_AnnualReturn2004	4.85%
05	rr_AnnualReturn2005	4.60%
06	rr_AnnualReturn2006	5.51%
07	rr_AnnualReturn2007	1.90%
08	rr_AnnualReturn2008	(9.41%)
09	rr_AnnualReturn2009	16.86%
10	rr_AnnualReturn2010	3.54%
11	rr_AnnualReturn2011	10.71%
12	rr_AnnualReturn2012	8.48%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	BEST QUARTER
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	7.66%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	WORST QUARTER
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(4.69%)
1 Year	rr_AverageAnnualReturnYear01	5.26%	[6]
5 Years	rr_AverageAnnualReturnYear05	5.01%	[6]
10 Years	rr_AverageAnnualReturnYear10	4.92%	[6]
National Portfolio | CLASS B
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	(not currently offered to new investors)
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	3.00%	[7]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.06%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.01%
Total Other Expenses	rr_OtherExpensesOverAssets	0.13%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	1.58%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.07%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	1.51%	[3],[4],[5]
After 1 Year	rr_ExpenseExampleYear01	454
After 3 Years	rr_ExpenseExampleYear03	592
After 5 Years	rr_ExpenseExampleYear05	853
After 10 Years	rr_ExpenseExampleYear10	1,500
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	154
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	492
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	853
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,500
1 Year	rr_AverageAnnualReturnYear01	4.85%
5 Years	rr_AverageAnnualReturnYear05	4.93%
10 Years	rr_AverageAnnualReturnYear10	4.81%
National 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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[8]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.05%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.01%
Total Other Expenses	rr_OtherExpensesOverAssets	0.12%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	1.57%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.06%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	1.51%	[3],[4],[5]
After 1 Year	rr_ExpenseExampleYear01	254
After 3 Years	rr_ExpenseExampleYear03	490
After 5 Years	rr_ExpenseExampleYear05	849
After 10 Years	rr_ExpenseExampleYear10	1,861
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	154
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	490
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	849
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,861
1 Year	rr_AverageAnnualReturnYear01	6.73%
5 Years	rr_AverageAnnualReturnYear05	4.92%
10 Years	rr_AverageAnnualReturnYear10	4.52%
National 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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.04%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.01%
Total Other Expenses	rr_OtherExpensesOverAssets	0.11%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	0.56%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	0.51%	[3],[4],[5]
After 1 Year	rr_ExpenseExampleYear01	52
After 3 Years	rr_ExpenseExampleYear03	174
After 5 Years	rr_ExpenseExampleYear05	308
After 10 Years	rr_ExpenseExampleYear10	696
1 Year	rr_AverageAnnualReturnYear01	8.81%	[9]
5 Years	rr_AverageAnnualReturnYear05	5.97%	[9]
10 Years	rr_AverageAnnualReturnYear10	5.56%	[9]
Inception Date	rr_AverageAnnualReturnInceptionDate	Aug. 06, 2008
National Portfolio | Return After Taxes on Distributions | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.25%	[6]
5 Years	rr_AverageAnnualReturnYear05	4.99%	[6]
10 Years	rr_AverageAnnualReturnYear10	4.89%	[6]
National Portfolio | Return After Taxes on Distributions and Sale of Portfolio Shares | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.73%	[6]
5 Years	rr_AverageAnnualReturnYear05	4.86%	[6]
10 Years	rr_AverageAnnualReturnYear10	4.82%	[6]
National Portfolio | Barclays Municipal Bond Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	6.78%
5 Years	rr_AverageAnnualReturnYear05	5.91%
10 Years	rr_AverageAnnualReturnYear10	5.10%

[1] Including Interest Expense Before Waiver

[2] The fee waiver and/or expense reimbursement agreement will remain in effect until January 31, 2014 and will be automatically extended for one-year terms thereafter unless terminated by the Adviser upon 60 days' notice to the Portfolio prior to that date.

[3] Restated to reflect current fee waiver and/or expense reimbursement.

[4] If interest expense were excluded, net expenses would be as follows: Class A Class B Class C Advisor Class ---------- .80% 1.50% 1.50% .50%

[5] Including Interest Expense After Fee Waiver and/or Expense Reimbursement

[6] After-tax Returns: - Are shown for Class A shares only and will vary for Class B and C shares because these Classes have higher expense ratios; - 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.

[7] Class B shares automatically convert to Class A shares after six years. The contingent deferred sales charge, or CDSC, decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the third year.

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

[9] Inception date for Advisor Class shares: 8/6/2008. Performance information for periods prior to the inception of Advisor Class shares is the performance of the Portfolio's Class A shares adjusted to reflect the lower expense ratio of Advisor Class shares.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	ALLIANCEBERNSTEIN MUNICIPAL INCOME FUND INC
Prospectus Date	rr_ProspectusDate	Jan. 31, 2013
New York Portfolio
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	NEW YORK PORTFOLIO
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE:
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of the Portfolio is to earn the highest level of current income exempt from both federal income tax and New York State and City income tax that is available without assuming what the Adviser considers to be undue risk to principal or income.
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 and hold shares of the Portfolio. 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 Portfolios—Sales Charge Reduction Programs for Class A Shares on page 75 of this Prospectus, and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 149 of the Portfolio's SAI.
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)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
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 14% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	14.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	Class B shares automatically convert to Class A shares after six years. The CDSC decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the third year. For Class C shares, the CDSC is 0% after the first year.
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AllianceBernstein Mutual Funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	100,000
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	Restated to reflect current fee waiver and/or expense reimbursement.
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, that the Portfolio's operating expenses stay the same and that the fee waiver remains in effect for only one year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	For the share classes listed below, you would pay the following expenses if you did not redeem your shares at the end of the period:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL STRATEGIES:
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Portfolio pursues its objective by investing principally in high-yielding, predominantly investment grade municipal securities. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities that pay interest that is exempt from federal income tax. These securities may pay interest that is subject to the federal AMT for certain taxpayers. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities of New York or municipal securities with interest that is otherwise exempt from New York state income tax. The Portfolio may also invest in: forward commitments; zero-coupon municipal securities and variable, floating and inverse floating rate municipal securities; and derivatives, such as options, futures, forwards and swaps.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS:
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	MARKET RISK: The value of the Portfolio's assets will fluctuate as the bond market fluctuates. The value of the Portfolio's investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market. CREDIT RISK: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security. Investments in fixed-income securities with lower ratings tend to have a higher probability that an issuer will default or fail to meet its payment obligations. 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, or the rights of investors in these securities. The Portfolio's investments in New York municipal securities may be vulnerable to events adversely affecting its economy. New York's economy, while diverse, has a relatively large share of the nation's financial activities. With the financial services sector contributing over one-fifth of the state's wages, the state's economy is especially vulnerable to adverse events affecting the financial markets such as occurred in 2008-2009. 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, may have increased risks. 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. TAX RISK: There is no guarantee that all of the Portfolio's income will remain exempt from federal or state income taxes. From time to time, the U.S. Government and the U.S. Congress consider changes in federal tax law that could limit or eliminate the federal tax exemption for municipal bond income, which would in effect reduce the income received by shareholders from the Portfolio by increasing taxes on that income. In such event, the Portfolio's NAV could also decline as yields on municipal bonds, which are typically lower than those on taxable bonds, would be expected to increase to approximately the yield of comparable taxable bonds. Actions or anticipated actions affecting the tax exempt status of municipal bonds could also result in significant shareholder redemptions of Portfolio shares as investors anticipate adverse effects on the Portfolio or seek higher yields to offset the potential loss of the tax deduction. As a result, the Portfolio would be required to maintain higher levels of cash to meet the redemptions, which would negatively affect the Portfolio's yield. INTEREST RATE RISK: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest rate risk is generally greater for fixed-income securities with longer maturities or durations. DURATION RISK: Duration is a measure that relates the expected price volatility of a fixed-income security to changes in interest rates. The duration of a fixed-income security may be shorter than or equal to full maturity of a fixed-income security. Fixed–income securities with longer durations have more risk and will decrease in price as interest rates rise. For example, a fixed–income security with a duration of three years will decrease in value by approximately 3% if interest rates increase by 1%. 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. LIQUIDITY RISK: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Portfolio from selling out of these illiquid securities at an advantageous price. Derivatives and securities involving substantial market and credit risk tend to involve greater liquidity risk. The Portfolio is subject to liquidity risk because the market for municipal securities is generally smaller than many other markets. DERIVATIVES RISK: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Portfolio, and may be subject to counterparty risk to a greater degree than more traditional investments. MANAGEMENT RISK: The Portfolio 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. As with all investments, you may lose money by investing in the Portfolio.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with all investments, you may lose money by investing in the Portfolio.
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: 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. You may obtain updated performance information on the Portfolio's website at www.AllianceBernstein.com (click on "Individuals-U.S." then "Products & Performance"). The Portfolio'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 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.AllianceBernstein.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.
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 6.36%, 3RD QUARTER , 2009; AND WORST QUARTER WAS DOWN -3.73%, 4TH QUARTER, 2010.
Performance Table Heading	rr_PerformanceTableHeading	Performance Table Average Annual Total Returns (For the periods ended December 31, 2012)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	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	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 B and C shares because these Classes have higher expense ratios;
New York 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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.30%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.03%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.07%
Total Other Expenses	rr_OtherExpensesOverAssets	0.10%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	0.85%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	0.80%	[3],[4]
After 1 Year	rr_ExpenseExampleYear01	379
After 3 Years	rr_ExpenseExampleYear03	558
After 5 Years	rr_ExpenseExampleYear05	752
After 10 Years	rr_ExpenseExampleYear10	1,313
03	rr_AnnualReturn2003	6.08%
04	rr_AnnualReturn2004	5.24%
05	rr_AnnualReturn2005	4.17%
06	rr_AnnualReturn2006	5.01%
07	rr_AnnualReturn2007	2.63%
08	rr_AnnualReturn2008	(4.69%)
09	rr_AnnualReturn2009	13.00%
10	rr_AnnualReturn2010	2.67%
11	rr_AnnualReturn2011	9.56%
12	rr_AnnualReturn2012	6.41%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	BEST QUARTER
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	6.36%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	WORST QUARTER
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2010
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(3.73%)
1 YEAR	rr_AverageAnnualReturnYear01	3.25%	[5]
5 YEARS	rr_AverageAnnualReturnYear05	4.58%	[5]
10 YEARS	rr_AverageAnnualReturnYear10	4.60%	[5]
New York Portfolio | CLASS B
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	(not currently offered to new investors)
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	3.00%	[6]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.05%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.07%
Total Other Expenses	rr_OtherExpensesOverAssets	0.12%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	1.57%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.07%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	1.50%	[3],[4]
After 1 Year	rr_ExpenseExampleYear01	453
After 3 Years	rr_ExpenseExampleYear03	589
After 5 Years	rr_ExpenseExampleYear05	849
After 10 Years	rr_ExpenseExampleYear10	1,490
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	153
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	489
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	849
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,490
1 YEAR	rr_AverageAnnualReturnYear01	2.68%
5 YEARS	rr_AverageAnnualReturnYear05	4.49%
10 YEARS	rr_AverageAnnualReturnYear10	4.48%
New York 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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[7]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.04%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Total Other Expenses	rr_OtherExpensesOverAssets	0.10%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	1.55%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.05%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	1.50%	[3],[4]
After 1 Year	rr_ExpenseExampleYear01	253
After 3 Years	rr_ExpenseExampleYear03	485
After 5 Years	rr_ExpenseExampleYear05	840
After 10 Years	rr_ExpenseExampleYear10	1,841
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	153
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	485
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	840
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,841
1 YEAR	rr_AverageAnnualReturnYear01	4.77%
5 YEARS	rr_AverageAnnualReturnYear05	4.50%
10 YEARS	rr_AverageAnnualReturnYear10	4.20%
New York 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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.03%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Total Other Expenses	rr_OtherExpensesOverAssets	0.09%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	0.54%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	0.50%	[3],[4]
After 1 Year	rr_ExpenseExampleYear01	51
After 3 Years	rr_ExpenseExampleYear03	169
After 5 Years	rr_ExpenseExampleYear05	298
After 10 Years	rr_ExpenseExampleYear10	673
1 YEAR	rr_AverageAnnualReturnYear01	6.73%	[8]
5 YEARS	rr_AverageAnnualReturnYear05	5.53%	[8]
10 YEARS	rr_AverageAnnualReturnYear10	5.23%	[8]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Aug. 06, 2008
New York Portfolio | Return After Taxes on Distributions | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	3.21%	[5]
5 YEARS	rr_AverageAnnualReturnYear05	4.56%	[5]
10 YEARS	rr_AverageAnnualReturnYear10	4.59%	[5]
New York Portfolio | Return After Taxes on Distributions and Sale of Portfolio Shares | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	3.34%	[5]
5 YEARS	rr_AverageAnnualReturnYear05	4.45%	[5]
10 YEARS	rr_AverageAnnualReturnYear10	4.53%	[5]
New York Portfolio | Barclays Municipal Bond Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	6.78%
5 YEARS	rr_AverageAnnualReturnYear05	5.91%
10 YEARS	rr_AverageAnnualReturnYear10	5.10%

[1] Before Waiver

[2] The fee waiver and/or expense reimbursement agreement will remain in effect until January 31, 2014 and will be automatically extended for one-year terms thereafter unless terminated by the Adviser upon 60 days' notice to the Portfolio prior to that date.

[3] Restated to reflect current fee waiver and/or expense reimbursement.

[4] After Fee Waiver and/or Expense Reimbursement

[5] After-tax Returns: - Are shown for Class A shares only and will vary for Class B and C shares because these Classes have higher expense ratios; - 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.

[6] Class B shares automatically convert to Class A shares after six years. The CDSC decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the third year.

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

[8] Inception date for Advisor Class shares: 8/6/08. Performance information for periods prior to the inception of Advisor Class shares is the performance of the Portfolio's Class A shares adjusted to reflect the lower expense ratio of Advisor Class shares.

XML

National Portfolio

National Portfolio

INVESTMENT OBJECTIVE:

The investment objective of the Portfolio is to earn the highest level of current income, exempt from federal income tax, that is available without assuming what the Adviser considers to be undue risk to principal or income.

FEES AND EXPENSES OF THE PORTFOLIO:

This table describes the fees and expenses that you may pay if you buy and hold shares of the Portfolio. 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 Portfolios—Sales Charge Reduction Programs for Class A Shares on page 75 of this Prospectus and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 149 of the Portfolio's Statement of Additional Information ("SAI").

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees National Portfolio (USD $)	CLASS A SHARES	CLASS B SHARES		CLASS C SHARES		ADVISOR CLASS SHARES
Shareholder Fees Column [Text]		(not currently offered to new investors)
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	3.00%	none		none		none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	none	3.00%	[1]	1.00%	[2]	none
Exchange Fee	none	none		none		none

Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Portfolio Operating Expenses National Portfolio		CLASS A	CLASS B	CLASS C	ADVISOR CLASS
Management Fees		0.45%	0.45%	0.45%	0.45%
Distribution and/or Service (12b-1) Fees		0.30%	1.00%	1.00%	none
Other Expenses: Transfer Agent		0.04%	0.06%	0.05%	0.04%
Other Expenses: Interest Expense		0.01%	0.01%	0.01%	0.01%
Other Expenses		0.06%	0.06%	0.06%	0.06%
Total Other Expenses		0.11%	0.13%	0.12%	0.11%
Total Annual Portfolio Operating Expenses	[1]	0.86%	1.58%	1.57%	0.56%
Fee Waiver and/or Expense Reimbursement	[2][3]	(0.05%)	(0.07%)	(0.06%)	(0.05%)
Total Annual Portfolio Operating Expenses	[3][4][5]	0.81%	1.51%	1.51%	0.51%

Examples

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 and that the fee waiver remains in effect for only one year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example National Portfolio (USD $)	CLASS A	CLASS B	CLASS C	ADVISOR CLASS
After 1 Year	380	454	254	52
After 3 Years	561	592	490	174
After 5 Years	758	853	849	308
After 10 Years	1,324	1,500	1,861	696

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:

Expense Example, No Redemption National Portfolio (USD $)	CLASS B	CLASS C
After 1 Year	154	154
After 3 Years	492	490
After 5 Years	853	849
After 10 Years	1,500	1,861

Portfolio Turnover

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 11% of the average value of its portfolio.

PRINCIPAL STRATEGIES:

The Portfolio pursues its objective by investing principally in high-yielding, predominantly investment grade municipal securities. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities that pay interest that is exempt from federal income tax. These securities may pay interest that is subject to the federal alternative minimum tax ("AMT") for certain taxpayers. The Portfolio may invest more than 25% of its assets in a single state.

The Portfolio may also invest in:

• forward commitments;

• tender option bonds ("TOBs");

• zero-coupon municipal securities and variable, floating and inverse floating rate municipal securities; and

• derivatives, such as options, futures, forwards and swaps.

PRINCIPAL RISKS:

• MARKET RISK: The value of the Portfolio's assets will fluctuate as the bond market fluctuates. The value of the Portfolio's investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market.

• CREDIT RISK: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security. Investments in fixed-income securities with lower ratings tend to have a higher probability that an issuer will default or fail to meet its payment obligations.

• 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, or the rights of investors in these securities. To the extent that the Portfolio invests more of its assets in a particular state's municipal securities, the Portfolio may be vulnerable to events adversely affecting that state, including economic, political and regulatory occurrences, court decisions, terrorism and catastrophic natural disasters, such as hurricanes or earthquakes. 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, may have increased risks. 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.

• TAX RISK: There is no guarantee that all of the Portfolio's income will remain exempt from federal or state income taxes. From time to time, the U.S. Government and the U.S. Congress consider changes in federal tax law that could limit or eliminate the federal tax exemption for municipal bond income, which would in effect reduce the income received by shareholders from the Portfolio by increasing taxes on that income. In such event, the Portfolio's net asset value, or NAV, could also decline as yields on municipal bonds, which are typically lower than those on taxable bonds, would be expected to increase to approximately the yield of comparable taxable bonds. Actions or anticipated actions affecting the tax exempt status of municipal bonds could also result in significant shareholder redemptions of Portfolio shares as investors anticipate adverse effects on the Portfolio or seek higher yields to offset the potential loss of the tax deduction. As a result, the Portfolio would be required to maintain higher levels of cash to meet the redemptions, which would negatively affect the Portfolio's yield.

• INTEREST RATE RISK: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest rate risk is generally greater for fixed-income securities with longer maturities or durations.

• DURATION RISK: Duration is a measure that relates the expected price volatility of a fixed-income security to changes in interest rates. The duration of a fixed-income security may be shorter than or equal to full maturity of a fixed-income security. Fixed-income securities with longer durations have more risk and will decrease in price as interest rates rise. For example, a fixed-income security with a duration of three years will decrease in value by approximately 3% if interest rates increase by 1%.

• 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.

• LIQUIDITY RISK: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Portfolio from selling out of these illiquid securities at an advantageous price. Derivatives and securities involving substantial market and credit risk tend to involve greater liquidity risk. The Portfolio is subject to liquidity risk because the market for municipal securities is generally smaller than many other markets.

• DERIVATIVES RISK: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Portfolio, and may be subject to counterparty risk to a greater degree than more traditional investments.

• MANAGEMENT RISK: The Portfolio 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.

As with all investments, you may lose money by investing in the Portfolio.

BAR CHART AND PERFORMANCE INFORMATION:

The bar chart and performance information provide an indication of the historical risk of an investment in the Portfolio by showing:

• 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.

You may obtain updated performance information on the Portfolio's website at www.AllianceBernstein.com (click on "Individuals—U.S." then "Products & Performance").

The Portfolio's past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future.

Bar Chart

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.

Calendar Year End (%)

During the period shown in the bar chart, the Portfolio's:

BEST QUARTER WAS UP 7.66%, 3RD QUARTER, 2009; AND WORST QUARTER WAS DOWN -4.69%, 4TH QUARTER, 2008.

Performance Table
Average Annual Total Returns
(For the periods ended December 31, 2012)

Average Annual Total Returns National Portfolio		1 YEAR		5 YEARS		10 YEARS		INCEPTION DATE
CLASS A	[1]	5.26%		5.01%		4.92%
CLASS A Return After Taxes on Distributions	[1]	5.25%		4.99%		4.89%
CLASS A Return After Taxes on Distributions and Sale of Portfolio Shares	[1]	4.73%		4.86%		4.82%
CLASS B		4.85%		4.93%		4.81%
CLASS C		6.73%		4.92%		4.52%
ADVISOR CLASS		8.81%	[2]	5.97%	[2]	5.56%	[2]	Aug. 06, 2008
Barclays Municipal Bond Index (reflects no deduction for fees, expenses or taxes)		6.78%		5.91%		5.10%

[1] Class B shares automatically convert to Class A shares after six years. The contingent deferred sales charge, or CDSC, decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the third year.

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

[1] Including Interest Expense Before Waiver

[2] The fee waiver and/or expense reimbursement agreement will remain in effect until January 31, 2014 and will be automatically extended for one-year terms thereafter unless terminated by the Adviser upon 60 days' notice to the Portfolio prior to that date.

[3] Restated to reflect current fee waiver and/or expense reimbursement.

[4] If interest expense were excluded, net expenses would be as follows: Class A Class B Class C Advisor Class ---------- .80% 1.50% 1.50% .50%

[5] Including Interest Expense After Fee Waiver and/or Expense Reimbursement

[1] After-tax Returns: - Are shown for Class A shares only and will vary for Class B and C shares because these Classes have higher expense ratios; - 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.

[2] Inception date for Advisor Class shares: 8/6/2008. Performance information for periods prior to the inception of Advisor Class shares is the performance of the Portfolio's Class A shares adjusted to reflect the lower expense ratio of Advisor Class shares.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	ALLIANCEBERNSTEIN MUNICIPAL INCOME FUND INC
Prospectus Date	rr_ProspectusDate	Jan. 31, 2013
California Portfolio
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	California Portfolio
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE:
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of the Portfolio is to earn the highest level of current income, exempt from federal income tax and California personal income tax, that is available without assuming what the Adviser considers to be undue risk to income or principal.
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 and hold shares of the Portfolio. 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 Portfolios—Sales Charge Reduction Programs for Class A Shares on page 75 of this Prospectus, and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 149 of the Portfolio's SAI.
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)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
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 23% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	23.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	Class B shares automatically convert to Class A shares after six years. The CDSC decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the third year. For Class C shares, the CDSC is 0% after the first year.
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AllianceBernstein Mutual Funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	100,000
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	Restated to reflect current fee waiver and/or expense reimbursement.
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, that the Portfolio's operating expenses stay the same and that the fee waiver remains in effect for only one year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	For the share classes listed below, you would pay the following expenses if you did not redeem your shares at the end of the period:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL STRATEGIES:
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Portfolio pursues its objective by investing principally in high-yielding, predominantly investment grade municipal securities. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities that pay interest that is exempt from federal income tax. These securities may pay interest that is subject to the federal AMT for certain taxpayers. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities of California or municipal securities with interest that is otherwise exempt from California state income tax. The Portfolio may also invest in: forward commitments; TOBs; zero-coupon municipal securities and variable, floating and inverse floating rate municipal securities; and derivatives, such as options, futures, forwards and swaps.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS:
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	MARKET RISK: The value of the Portfolio's assets will fluctuate as the bond market fluctuates. The value of the Portfolio's investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market. CREDIT RISK: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security. Investments in fixed-income securities with lower ratings tend to have a higher probability that an issuer will default or fail to meet its payment obligations. 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, or the rights of investors in these securities. The Portfolio's investments in California municipal securities may be vulnerable to events adversely affecting its economy. California's economy, the largest of the 50 states, is relatively diverse, which makes it less vulnerable to events affecting a particular industry. Its economy, however, continues to be affected by serious fiscal conditions as a result of voter-passed initiatives that limit the ability of state and local governments to raise revenues, particularly with respect to real property taxes. In addition, state expenditures are difficult to reduce because of constitutional provisions that require a minimum level of spending, for certain government programs, such as education. California's economy may also be affected by natural disasters, such as earthquakes or fires. 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, may have increased risks. 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. TAX RISK: There is no guarantee that all of the Portfolio's income will remain exempt from federal or state income taxes. From time to time, the U.S. Government and the U.S. Congress consider changes in federal tax law that could limit or eliminate the federal tax exemption for municipal bond income, which would in effect reduce the income received by shareholders from the Portfolio by increasing taxes on that income. In such event, the Portfolio's NAV could also decline as yields on municipal bonds, which are typically lower than those on taxable bonds, would be expected to increase to approximately the yield of comparable taxable bonds. Actions or anticipated actions affecting the tax exempt status of municipal bonds could also result in significant shareholder redemptions of Portfolio shares as investors anticipate adverse effects on the Portfolio or seek higher yields to offset the potential loss of the tax deduction. As a result, the Portfolio would be required to maintain higher levels of cash to meet the redemptions, which would negatively affect the Portfolio's yield. INTEREST RATE RISK: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest rate risk is generally greater for fixed-income securities with longer maturities or durations. DUARTION RISK: Duration is a measure that relates the expected price volatility of a fixed-income security to changes in interest rates. The duration of a fixed-income security may be shorter than or equal to full maturity of a fixed-income security. Fixed-income securities with longer durations have more risk and will decrease in price as interest rates rise. For example, a fixed-income security with a duration of three years will decrease in value by approximately 3% if interest rates increase by 1%. 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. LIQUIDITY RISK: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Portfolio from selling out of these illiquid securities at an advantageous price. Derivatives and securities involving substantial market and credit risk tend to involve greater liquidity risk. The Portfolio is subject to liquidity risk because the market for municipal securities is generally smaller than many other markets. DERIVATIVES RISK: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Portfolio, and may be subject to counterparty risk to a greater degree than more traditional investments. MANAGEMENT RISK: The Portfolio 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. As with all investments, you may lose money by investing in the Portfolio.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with all investments, you may lose money by investing in the Portfolio.
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: 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. You may obtain updated performance information on the Portfolio's website at www.AllianceBernstein.com (click on "Individuals—U.S." then "Products & Performance"). The Portfolio'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 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.AllianceBernstein.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.
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 8.64%, 3RD QUARTER, 2009; AND WORST QUARTER WAS DOWN -4.33%, 4TH QUARTER, 2010.
Performance Table Heading	rr_PerformanceTableHeading	Performance Table Average Annual Total Returns (For the periods ended December 31, 2012)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	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	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 B and C shares because these Classes have higher expense ratios;
California 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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.30%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.03%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.01%
Total Other Expenses	rr_OtherExpensesOverAssets	0.10%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	0.85%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	0.81%	[3],[4],[5]
After 1 Year	rr_ExpenseExampleYear01	380
After 3 Years	rr_ExpenseExampleYear03	559
After 5 Years	rr_ExpenseExampleYear05	753
After 10 Years	rr_ExpenseExampleYear10	1,314
03	rr_AnnualReturn2003	4.44%
04	rr_AnnualReturn2004	5.46%
05	rr_AnnualReturn2005	5.01%
06	rr_AnnualReturn2006	5.13%
07	rr_AnnualReturn2007	2.17%
08	rr_AnnualReturn2008	(7.31%)
09	rr_AnnualReturn2009	14.03%
10	rr_AnnualReturn2010	3.67%
11	rr_AnnualReturn2011	10.74%
12	rr_AnnualReturn2012	7.70%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	BEST QUARTER
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	8.64%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	WORST QUARTER
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2010
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(4.33%)
1 YEAR	rr_AverageAnnualReturnYear01	4.48%	[6]
5 YEARS	rr_AverageAnnualReturnYear05	4.87%	[6]
10 YEARS	rr_AverageAnnualReturnYear10	4.64%	[6]
California Portfolio | CLASS B
Risk/Return:	rr_RiskReturnAbstract
Shareholder Fees Column [Text]	rr_ShareholderFeesColumnName	(not currently offered to new investors)
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	3.00%	[7]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.06%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.01%
Total Other Expenses	rr_OtherExpensesOverAssets	0.13%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	1.58%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.07%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	1.51%	[3],[4],[5]
After 1 Year	rr_ExpenseExampleYear01	454
After 3 Years	rr_ExpenseExampleYear03	592
After 5 Years	rr_ExpenseExampleYear05	854
After 10 Years	rr_ExpenseExampleYear10	1,496
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	154
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	492
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	854
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,496
1 YEAR	rr_AverageAnnualReturnYear01	3.86%
5 YEARS	rr_AverageAnnualReturnYear05	4.75%
10 YEARS	rr_AverageAnnualReturnYear10	4.53%
California 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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[8]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.03%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.01%
Total Other Expenses	rr_OtherExpensesOverAssets	0.10%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	1.55%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	1.51%	[3],[4],[5]
After 1 Year	rr_ExpenseExampleYear01	254
After 3 Years	rr_ExpenseExampleYear03	486
After 5 Years	rr_ExpenseExampleYear05	841
After 10 Years	rr_ExpenseExampleYear10	1,842
After 1 Year	rr_ExpenseExampleNoRedemptionYear01	154
After 3 Years	rr_ExpenseExampleNoRedemptionYear03	486
After 5 Years	rr_ExpenseExampleNoRedemptionYear05	841
After 10 Years	rr_ExpenseExampleNoRedemptionYear10	1,842
1 YEAR	rr_AverageAnnualReturnYear01	5.86%
5 YEARS	rr_AverageAnnualReturnYear05	4.75%
10 YEARS	rr_AverageAnnualReturnYear10	4.23%
California 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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.03%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.01%
Total Other Expenses	rr_OtherExpensesOverAssets	0.10%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	0.55%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.04%)	[2],[3]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	0.51%	[3],[4],[5]
After 1 Year	rr_ExpenseExampleYear01	52
After 3 Years	rr_ExpenseExampleYear03	172
After 5 Years	rr_ExpenseExampleYear05	303
After 10 Years	rr_ExpenseExampleYear10	685
1 YEAR	rr_AverageAnnualReturnYear01	8.02%	[9]
5 YEARS	rr_AverageAnnualReturnYear05	5.81%	[9]
10 YEARS	rr_AverageAnnualReturnYear10	5.28%	[9]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Aug. 06, 2008
California Portfolio | Return After Taxes on Distributions | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	4.42%	[6]
5 YEARS	rr_AverageAnnualReturnYear05	4.83%	[6]
10 YEARS	rr_AverageAnnualReturnYear10	4.61%	[6]
California Portfolio | Return After Taxes on Distributions and Sale of Portfolio Shares | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	4.22%	[6]
5 YEARS	rr_AverageAnnualReturnYear05	4.72%	[6]
10 YEARS	rr_AverageAnnualReturnYear10	4.56%	[6]
California Portfolio | Barclays Municipal Bond Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	6.78%
5 YEARS	rr_AverageAnnualReturnYear05	5.91%
10 YEARS	rr_AverageAnnualReturnYear10	5.10%

[1] Including Interest Expense Before Waiver

[2] The fee waiver and/or expense reimbursement agreement will remain in effect until January 31, 2014 and will be automatically extended for one-year terms thereafter unless terminated by the Adviser upon 60 days' notice to the Portfolio prior to that date.

[3] Restated to reflect current fee waiver and/or expense reimbursement.

[4] If interest expense were excluded, net expenses would be as follows: Class A Class B Class C Advisor Class ---------- .80% 1.50% 1.50% .50%

[5] After Fee Waiver and/or Expense Reimbursement

[6] After-tax Returns: - Are shown for Class A shares only and will vary for Class B and C shares because these Classes have higher expense ratios; - 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.

[7] Class B shares automatically convert to Class A shares after six years. The CDSC decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the third year.

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

[9] Inception date for Advisor Class shares: 8/6/2008. Performance information for periods prior to the inception of Advisor Class shares is the performance of the Portfolio's Class A shares adjusted to reflect the lower expense ratio of Advisor Class shares.

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California Portfolio

California Portfolio

INVESTMENT OBJECTIVE:

The investment objective of the Portfolio is to earn the highest level of current income, exempt from federal income tax and California personal income tax, that is available without assuming what the Adviser considers to be undue risk to income or principal.

FEES AND EXPENSES OF THE PORTFOLIO:

This table describes the fees and expenses that you may pay if you buy and hold shares of the Portfolio. 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 Portfolios—Sales Charge Reduction Programs for Class A Shares on page 75 of this Prospectus, and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 149 of the Portfolio's SAI.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees California Portfolio (USD $)	CLASS A SHARES	CLASS B SHARES		CLASS C SHARES		ADVISOR CLASS SHARES
Shareholder Fees Column [Text]		(not currently offered to new investors)
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	3.00%	none		none		none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	none	3.00%	[1]	1.00%	[2]	none
Exchange Fee	none	none		none		none

Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Portfolio Operating Expenses California Portfolio		CLASS A	CLASS B	CLASS C	ADVISOR CLASS
Management Fees		0.45%	0.45%	0.45%	0.45%
Distribution and/or Service (12b-1) Fees		0.30%	1.00%	1.00%	none
Other Expenses: Transfer Agent		0.03%	0.06%	0.03%	0.03%
Other Expenses: Interest Expense		0.01%	0.01%	0.01%	0.01%
Other Expenses		0.06%	0.06%	0.06%	0.06%
Total Other Expenses		0.10%	0.13%	0.10%	0.10%
Total Annual Portfolio Operating Expenses	[1]	0.85%	1.58%	1.55%	0.55%
Fee Waiver and/or Expense Reimbursement	[2][3]	(0.04%)	(0.07%)	(0.04%)	(0.04%)
Total Annual Portfolio Operating Expenses	[3][4][5]	0.81%	1.51%	1.51%	0.51%

Examples

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, that the Portfolio's operating expenses stay the same and that the fee waiver remains in effect for only one year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example California Portfolio (USD $)	CLASS A	CLASS B	CLASS C	ADVISOR CLASS
After 1 Year	380	454	254	52
After 3 Years	559	592	486	172
After 5 Years	753	854	841	303
After 10 Years	1,314	1,496	1,842	685

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:

Expense Example, No Redemption California Portfolio (USD $)	CLASS B	CLASS C
After 1 Year	154	154
After 3 Years	492	486
After 5 Years	854	841
After 10 Years	1,496	1,842

Portfolio Turnover

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 23% of the average value of its portfolio.

PRINCIPAL STRATEGIES:

The Portfolio pursues its objective by investing principally in high-yielding, predominantly investment grade municipal securities. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities that pay interest that is exempt from federal income tax. These securities may pay interest that is subject to the federal AMT for certain taxpayers. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities of California or municipal securities with interest that is otherwise exempt from California state income tax.

The Portfolio may also invest in:

• forward commitments;

• TOBs;

• zero-coupon municipal securities and variable, floating and inverse floating rate municipal securities; and

• derivatives, such as options, futures, forwards and swaps.

PRINCIPAL RISKS:

• MARKET RISK: The value of the Portfolio's assets will fluctuate as the bond market fluctuates. The value of the Portfolio's investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market.

• CREDIT RISK: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security. Investments in fixed-income securities with lower ratings tend to have a higher probability that an issuer will default or fail to meet its payment obligations.

• 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, or the rights of investors in these securities. The Portfolio's investments in California municipal securities may be vulnerable to events adversely affecting its economy. California's economy, the largest of the 50 states, is relatively diverse, which makes it less vulnerable to events affecting a particular industry. Its economy, however, continues to be affected by serious fiscal conditions as a result of voter-passed initiatives that limit the ability of state and local governments to raise revenues, particularly with respect to real property taxes. In addition, state expenditures are difficult to reduce because of constitutional provisions that require a minimum level of spending, for certain government programs, such as education. California's economy may also be affected by natural disasters, such as earthquakes or fires. 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, may have increased risks. 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.

• TAX RISK: There is no guarantee that all of the Portfolio's income will remain exempt from federal or state income taxes. From time to time, the U.S. Government and the U.S. Congress consider changes in federal tax law that could limit or eliminate the federal tax exemption for municipal bond income, which would in effect reduce the income received by shareholders from the Portfolio by increasing taxes on that income. In such event, the Portfolio's NAV could also decline as yields on municipal bonds, which are typically lower than those on taxable bonds, would be expected to increase to approximately the yield of comparable taxable bonds. Actions or anticipated actions affecting the tax exempt status of municipal bonds could also result in significant shareholder redemptions of Portfolio shares as investors anticipate adverse effects on the Portfolio or seek higher yields to offset the potential loss of the tax deduction. As a result, the Portfolio would be required to maintain higher levels of cash to meet the redemptions, which would negatively affect the Portfolio's yield.

• INTEREST RATE RISK: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest rate risk is generally greater for fixed-income securities with longer maturities or durations.

• DUARTION RISK: Duration is a measure that relates the expected price volatility of a fixed-income security to changes in interest rates. The duration of a fixed-income security may be shorter than or equal to full maturity of a fixed-income security. Fixed-income securities with longer durations have more risk and will decrease in price as interest rates rise. For example, a fixed-income security with a duration of three years will decrease in value by approximately 3% if interest rates increase by 1%.

• 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.

• LIQUIDITY RISK: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Portfolio from selling out of these illiquid securities at an advantageous price. Derivatives and securities involving substantial market and credit risk tend to involve greater liquidity risk. The Portfolio is subject to liquidity risk because the market for municipal securities is generally smaller than many other markets.

• DERIVATIVES RISK: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Portfolio, and may be subject to counterparty risk to a greater degree than more traditional investments.

• MANAGEMENT RISK: The Portfolio 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.

As with all investments, you may lose money by investing in the Portfolio.

BAR CHART AND PERFORMANCE INFORMATION:

The bar chart and performance information provide an indication of the historical risk of an investment in the Portfolio by showing:

• 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.

You may obtain updated performance information on the Portfolio's website at www.AllianceBernstein.com (click on "Individuals—U.S." then "Products & Performance").

The Portfolio's past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future.

Bar Chart

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.

Calendar Year End (%)

During the period shown in the bar chart, the Portfolio's:

BEST QUARTER WAS UP 8.64%, 3RD QUARTER, 2009; AND WORST QUARTER WAS DOWN -4.33%, 4TH QUARTER, 2010.

Performance Table
Average Annual Total Returns
(For the periods ended December 31, 2012)

Average Annual Total Returns California Portfolio		1 YEAR		5 YEARS		10 YEARS		INCEPTION DATE
CLASS A	[1]	4.48%		4.87%		4.64%
CLASS A Return After Taxes on Distributions	[1]	4.42%		4.83%		4.61%
CLASS A Return After Taxes on Distributions and Sale of Portfolio Shares	[1]	4.22%		4.72%		4.56%
CLASS B		3.86%		4.75%		4.53%
CLASS C		5.86%		4.75%		4.23%
ADVISOR CLASS		8.02%	[2]	5.81%	[2]	5.28%	[2]	Aug. 06, 2008
Barclays Municipal Bond Index (reflects no deduction for fees, expenses or taxes)		6.78%		5.91%		5.10%

[1] Class B shares automatically convert to Class A shares after six years. The CDSC decreases over time. For Class B shares the CDSC decreases 1.00% annually to 0% after the third year.

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

[1] Including Interest Expense Before Waiver

[2] The fee waiver and/or expense reimbursement agreement will remain in effect until January 31, 2014 and will be automatically extended for one-year terms thereafter unless terminated by the Adviser upon 60 days' notice to the Portfolio prior to that date.

[3] Restated to reflect current fee waiver and/or expense reimbursement.

[4] If interest expense were excluded, net expenses would be as follows: Class A Class B Class C Advisor Class ---------- .80% 1.50% 1.50% .50%

[5] After Fee Waiver and/or Expense Reimbursement

[1] After-tax Returns: - Are shown for Class A shares only and will vary for Class B and C shares because these Classes have higher expense ratios; - 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.

[2] Inception date for Advisor Class shares: 8/6/2008. Performance information for periods prior to the inception of Advisor Class shares is the performance of the Portfolio's Class A shares adjusted to reflect the lower expense ratio of Advisor Class shares.

XML

Document and Entity Information	12 Months Ended
	Jan. 31, 2013
Risk/Return:
Document Type	485BPOS
Document Period End Date	Oct. 31, 2012
Registrant Name	ALLIANCEBERNSTEIN MUNICIPAL INCOME FUND INC
Central Index Key	0000798737
Amendment Flag	false
Document Creation Date	Jan. 31, 2013
Document Effective Date	Jan. 31, 2013
Prospectus Date	Jan. 31, 2013

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	ALLIANCEBERNSTEIN MUNICIPAL INCOME FUND INC
Prospectus Date	rr_ProspectusDate	Jan. 31, 2013
AllianceBernstein High Income Municipal Portfolio
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	High Income Municipal Portfolio
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE:
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of the Portfolio is to earn the highest level of current income, exempt from federal income tax, that is available consistent with what the Adviser considers to be an appropriate level of risk.
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 and hold shares of the Portfolio. 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 Portfolios—Sales Charge Reduction Programs for Class A Shares on page 75 of this Prospectus and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 149 of the Portfolio's SAI.
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)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Portfolio will pay 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 period, the Portfolio's portfolio turnover rate was 14% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	14.00%
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 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. The Examples also assume that your investment has a 5% return each year, that the Portfolio's operating expenses stay the same and that the fee waiver remains 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 Portfolio pursues its objective by investing principally in high-yielding municipal securities that may be non-investment grade or investment grade. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities that pay interest that is exempt from federal income tax. These securities may pay interest that is subject to the federal AMT for certain taxpayers. The Adviser 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 Adviser 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. The Portfolio may invest without limit in lower-rated securities ("junk bonds"), which may include securities having the lowest rating, and in unrated securities that, in the Adviser's judgment, would be lower-rated securities if rated. The Portfolio may invest in fixed-income securities with any maturity or duration. The Portfolio will seek to increase income for shareholders by investing in longer-maturity bonds. Consistent with its objective of seeking a higher level of income, the Portfolio may experience greater volatility and a higher risk of loss of principal than other municipal funds. The Portfolio may also invest in: forward commitments; zero-coupon municipal securities and variable, floating and inverse floating rate municipal securities; certain types of mortgage-related securities; and derivatives, such as options, futures, forwards and swaps. The Portfolio may make short sales of securities or maintain a short position, and may use other investment techniques. The Portfolio may use leverage for investment purposes to increase income through the use of TOBs and derivative instruments, such as interest rate swaps.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS:
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	MARKET RISK: The value of the Portfolio's assets will fluctuate as the bond market fluctuates. The value of the Portfolio's investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market. CREDIT RISK: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security. BELOW INVESTMENT GRADE SECURITIES RISK: Investments in fixed-income securities with lower ratings (commonly known as "junk bonds") tend to have a higher probability that an issuer will default or fail to meet its payment obligations. These securities may be subject to greater price volatility due to such factors as specific corporate developments, interest rate sensitivity, negative performance of the junk bond market generally and less secondary market liquidity. 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, or the rights of investors in these securities. To the extent that the Portfolio invests more of its assets in a particular state's municipal securities, the Portfolio may be vulnerable to events adversely affecting that state, including economic, political and regulatory occurrences, court decisions, terrorism and catastrophic natural disasters, such as hurricanes or earthquakes. 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, may have increased risks. 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. TAX RISK: There is no guarantee that all of the Portfolio's income will remain exempt from federal or state income taxes. From time to time, the U.S. Government and the U.S. Congress consider changes in federal tax law that could limit or eliminate the federal tax exemption for municipal bond income, which would in effect reduce the income received by shareholders from the Portfolio by increasing taxes on that income. In such event, the Portfolio's NAV could also decline as yields on municipal bonds, which are typically lower than those on taxable bonds, would be expected to increase to approximately the yield of comparable taxable bonds. Actions or anticipated actions affecting the tax exempt status of municipal bonds could also result in significant shareholder redemptions of Portfolio shares as investors anticipate adverse effects on the Portfolio or seek higher yields to offset the potential loss of the tax deduction. As a result, the Portfolio would be required to maintain higher levels of cash to meet the redemptions, which would negatively affect the Portfolio's yield. INTEREST RATE RISK: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest rate risk is generally greater for fixed-income securities with longer maturities or durations. DURATION RISK: Duration is a measure that relates the expected price volatility of a fixed-income security to changes in interest rates. The duration of a fixed-income security may be shorter than or equal to full maturity of a fixed-income security. Fixed-income securities with longer durations have more risk and will decrease in price as interest rates rise. For example, a fixed-income security with a duration of three years will decrease in value by approximately 3% if interest rates increase by 1%. 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. LEVERAGE RISK: To the extent the Portfolio uses leveraging techniques, such as TOBs, its NAV may be more volatile because leverage tends to exaggerate the effect of changes in interest rates and any increase or decrease in the value of the Portfolio's investments. LIQUIDITY RISK: Liquidity risk exists when particular investments, such as lower-rated securities, are difficult to purchase or sell, possibly preventing the Portfolio from selling out of these illiquid securities at an advantageous price. Derivatives and securities involving substantial market and credit risk tend to involve greater liquidity risk. The Portfolio is subject to liquidity risk because the market for municipal securities is generally smaller than many other markets. DERIVATIVES RISK: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Portfolio, and may be subject to counterparty risk to a greater degree than more traditional investments. MANAGEMENT RISK: The Portfolio 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. As with all investments, you may lose money by investing in the Portfolio.
Risk Lose Money [Text]	rr_RiskLoseMoney	As with all investments, you may lose money by investing in the Portfolio.
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: how the Portfolio's performance changed over the life of the Portfolio; and how the Portfolio'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 Portfolio's website at www.AllianceBernstein.com (click on "Individuals—U.S." then "Products & Performance"). The Portfolio'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 Portfolio's performance changed over the life of the Portfolio; and how the Portfolio'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.AllianceBernstein.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 is 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 Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The annual returns in the bar chart is 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 6.20%, 2ND QUARTER, 2011; AND WORST QUARTER WAS DOWN -0.81%, 1ST QUARTER, 2011.
Performance Table Heading	rr_PerformanceTableHeading	Performance Table Average Annual Total Returns (For the periods ended December 31, 2012)
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	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	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 shares because Class C shares have higher expense ratios;
AllianceBernstein High Income 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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.30%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.03%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.06%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.11%
Total Other Expenses	rr_OtherExpensesOverAssets	0.20%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	1.00%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.09%)	[2]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	0.91%	[3],[4]
After 1 Year	rr_ExpenseExampleYear01	390
After 3 Years	rr_ExpenseExampleYear03	600
After 5 Years	rr_ExpenseExampleYear05	827
After 10 Years	rr_ExpenseExampleYear10	1,480
03	rr_AnnualReturn2003
04	rr_AnnualReturn2004
05	rr_AnnualReturn2005
06	rr_AnnualReturn2006
07	rr_AnnualReturn2007
08	rr_AnnualReturn2008
09	rr_AnnualReturn2009
10	rr_AnnualReturn2010
11	rr_AnnualReturn2011	12.92%
12	rr_AnnualReturn2012	16.61%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	BEST QUARTER
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2011
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	6.20%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	WORST QUARTER
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2011
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(0.81%)
1 YEAR	rr_AverageAnnualReturnYear01	13.13%	[5]
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	9.70%	[5],[6]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Jan. 26, 2010	[5]
AllianceBernstein High Income 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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[7]
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.03%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.07%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.11%
Total Other Expenses	rr_OtherExpensesOverAssets	0.21%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	1.71%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.10%)	[2]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	1.61%	[3],[4]
After 1 Year	rr_ExpenseExampleYear01	264	[8]
After 3 Years	rr_ExpenseExampleYear03	529
After 5 Years	rr_ExpenseExampleYear05	919
After 10 Years	rr_ExpenseExampleYear10	2,011
1 YEAR	rr_AverageAnnualReturnYear01	14.91%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	10.09%	[6]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Jan. 26, 2010
AllianceBernstein High Income 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_MaximumDeferredSalesChargeOverOfferingPrice	none
Exchange Fee	rr_ExchangeFee	none
Management Fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses: Transfer Agent	rr_Component1OtherExpensesOverAssets	0.03%
Other Expenses	rr_Component2OtherExpensesOverAssets	0.07%
Other Expenses: Interest Expense	rr_Component3OtherExpensesOverAssets	0.11%
Total Other Expenses	rr_OtherExpensesOverAssets	0.21%
Total Annual Portfolio Operating Expenses	rr_ExpensesOverAssets	0.71%	[1]
Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(0.10%)	[2]
Total Annual Portfolio Operating Expenses	rr_NetExpensesOverAssets	0.61%	[3],[4]
After 1 Year	rr_ExpenseExampleYear01	62
After 3 Years	rr_ExpenseExampleYear03	217
After 5 Years	rr_ExpenseExampleYear05	385
After 10 Years	rr_ExpenseExampleYear10	873
1 YEAR	rr_AverageAnnualReturnYear01	16.98%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	11.16%	[6]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Jan. 26, 2010
AllianceBernstein High Income Municipal Portfolio | Return After Taxes on Distributions | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	13.03%	[5]
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	9.52%	[5],[6]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Jan. 26, 2010	[5]
AllianceBernstein High Income Municipal Portfolio | Return After Taxes on Distributions and Sale of Portfolio Shares | CLASS A
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	10.26%	[5]
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	8.91%	[5],[6]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Jan. 26, 2010	[5]
AllianceBernstein High Income Municipal Portfolio | Barclays Municipal Bond Index (reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 YEAR	rr_AverageAnnualReturnYear01	6.78%
SINCE INCEPTION	rr_AverageAnnualReturnSinceInception	6.52%	[6]
INCEPTION DATE	rr_AverageAnnualReturnInceptionDate	Jan. 26, 2010

[1] Including Interest Expense Before Waiver

[2] The fee waiver and/or expense reimbursement agreement will remain in effect until January 31, 2014 and will be automatically extended for one-year terms thereafter unless terminated by the Adviser upon 60 days' notice to the Portfolio prior to that date.

[3] Including Interest Expense After Fee Waiver and/or Expense Reimbursement

[4] If interest expense were excluded, net expenses would be as follows: Class A Class C Advisor Class ---------- .80% 1.50% .50%

[5] After-tax Returns: -Are shown for Class A shares only and will vary for Class C shares because Class C shares have higher expense ratios; -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.

[6] Inception date for all Classes: 1/26/2010.

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

[8] Assuming redemption at the end of the period, a 1% CDSC would increase expenses by approximately $100.

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AllianceBernstein High Income Municipal Portfolio

High Income Municipal Portfolio

INVESTMENT OBJECTIVE:

The investment objective of the Portfolio is to earn the highest level of current income, exempt from federal income tax, that is available consistent with what the Adviser considers to be an appropriate level of risk.

FEES AND EXPENSES OF THE PORTFOLIO:

This table describes the fees and expenses that you may pay if you buy and hold shares of the Portfolio. 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 Portfolios—Sales Charge Reduction Programs for Class A Shares on page 75 of this Prospectus and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 149 of the Portfolio's SAI.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees AllianceBernstein High Income Municipal Portfolio (USD $)	CLASS A SHARES	CLASS C SHARES		ADVISOR CLASS SHARES
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)	3.00%	none		none
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower)	none	1.00%	[1]	none
Exchange Fee	none	none		none

Annual Portfolio Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Portfolio Operating Expenses AllianceBernstein High Income Municipal Portfolio		CLASS A	CLASS C	ADVISOR CLASS
Management Fees		0.50%	0.50%	0.50%
Distribution and/or Service (12b-1) Fees		0.30%	1.00%	none
Other Expenses: Transfer Agent		0.03%	0.03%	0.03%
Other Expenses: Interest Expense		0.11%	0.11%	0.11%
Other Expenses		0.06%	0.07%	0.07%
Total Other Expenses		0.20%	0.21%	0.21%
Total Annual Portfolio Operating Expenses	[1]	1.00%	1.71%	0.71%
Fee Waiver and/or Expense Reimbursement	[2]	(0.09%)	(0.10%)	(0.10%)
Total Annual Portfolio Operating Expenses	[3][4]	0.91%	1.61%	0.61%

Examples

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. The Examples also assume that your investment has a 5% return each year, that the Portfolio's operating expenses stay the same and that the fee waiver remains in effect for only the first year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example AllianceBernstein High Income Municipal Portfolio (USD $)	CLASS A	CLASS C		ADVISOR CLASS
After 1 Year	390	264	[1]	62
After 3 Years	600	529		217
After 5 Years	827	919		385
After 10 Years	1,480	2,011		873

Portfolio Turnover

The Portfolio will pay 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 period, the Portfolio's portfolio turnover rate was 14% of the average value of its portfolio.

PRINCIPAL STRATEGIES:

The Portfolio pursues its objective by investing principally in high-yielding municipal securities that may be non-investment grade or investment grade. As a matter of fundamental policy, the Portfolio invests, under normal circumstances, at least 80% of its net assets in municipal securities that pay interest that is exempt from federal income tax. These securities may pay interest that is subject to the federal AMT for certain taxpayers.

The Adviser 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 Adviser 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.

The Portfolio may invest without limit in lower-rated securities ("junk bonds"), which may include securities having the lowest rating, and in unrated securities that, in the Adviser's judgment, would be lower-rated securities if rated. The Portfolio may invest in fixed-income securities with any maturity or duration. The Portfolio will seek to increase income for shareholders by investing in longer-maturity bonds. Consistent with its objective of seeking a higher level of income, the Portfolio may experience greater volatility and a higher risk of loss of principal than other municipal funds.

The Portfolio may also invest in:

• forward commitments;

• zero-coupon municipal securities and variable, floating and inverse floating rate municipal securities;

• certain types of mortgage-related securities; and

• derivatives, such as options, futures, forwards and swaps.

The Portfolio may make short sales of securities or maintain a short position, and may use other investment techniques. The Portfolio may use leverage for investment purposes to increase income through the use of TOBs and derivative instruments, such as interest rate swaps.

PRINCIPAL RISKS:

• MARKET RISK: The value of the Portfolio's assets will fluctuate as the bond market fluctuates. The value of the Portfolio's investments may decline, sometimes rapidly and unpredictably, simply because of economic changes or other events that affect large portions of the market.

• CREDIT RISK: An issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other contract, may be unable or unwilling to make timely payments of interest or principal, or to otherwise honor its obligations. The issuer or guarantor may default, causing a loss of the full principal amount of a security. The degree of risk for a particular security may be reflected in its credit rating. There is the possibility that the credit rating of a fixed-income security may be downgraded after purchase, which may adversely affect the value of the security.

• BELOW INVESTMENT GRADE SECURITIES RISK: Investments in fixed-income securities with lower ratings (commonly known as "junk bonds") tend to have a higher probability that an issuer will default or fail to meet its payment obligations. These securities may be subject to greater price volatility due to such factors as specific corporate developments, interest rate sensitivity, negative performance of the junk bond market generally and less secondary market liquidity.

• 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, or the rights of investors in these securities. To the extent that the Portfolio invests more of its assets in a particular state's municipal securities, the Portfolio may be vulnerable to events adversely affecting that state, including economic, political and regulatory occurrences, court decisions, terrorism and catastrophic natural disasters, such as hurricanes or earthquakes. 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, may have increased risks. 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.

• TAX RISK: There is no guarantee that all of the Portfolio's income will remain exempt from federal or state income taxes. From time to time, the U.S. Government and the U.S. Congress consider changes in federal tax law that could limit or eliminate the federal tax exemption for municipal bond income, which would in effect reduce the income received by shareholders from the Portfolio by increasing taxes on that income. In such event, the Portfolio's NAV could also decline as yields on municipal bonds, which are typically lower than those on taxable bonds, would be expected to increase to approximately the yield of comparable taxable bonds. Actions or anticipated actions affecting the tax exempt status of municipal bonds could also result in significant shareholder redemptions of Portfolio shares as investors anticipate adverse effects on the Portfolio or seek higher yields to offset the potential loss of the tax deduction. As a result, the Portfolio would be required to maintain higher levels of cash to meet the redemptions, which would negatively affect the Portfolio's yield.

• INTEREST RATE RISK: Changes in interest rates will affect the value of investments in fixed-income securities. When interest rates rise, the value of investments in fixed-income securities tends to fall and this decrease in value may not be offset by higher income from new investments. Interest rate risk is generally greater for fixed-income securities with longer maturities or durations.

• DURATION RISK: Duration is a measure that relates the expected price volatility of a fixed-income security to changes in interest rates. The duration of a fixed-income security may be shorter than or equal to full maturity of a fixed-income security. Fixed-income securities with longer durations have more risk and will decrease in price as interest rates rise. For example, a fixed-income security with a duration of three years will decrease in value by approximately 3% if interest rates increase by 1%.

• 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.

• LEVERAGE RISK: To the extent the Portfolio uses leveraging techniques, such as TOBs, its NAV may be more volatile because leverage tends to exaggerate the effect of changes in interest rates and any increase or decrease in the value of the Portfolio's investments.

• LIQUIDITY RISK: Liquidity risk exists when particular investments, such as lower-rated securities, are difficult to purchase or sell, possibly preventing the Portfolio from selling out of these illiquid securities at an advantageous price. Derivatives and securities involving substantial market and credit risk tend to involve greater liquidity risk. The Portfolio is subject to liquidity risk because the market for municipal securities is generally smaller than many other markets.

• DERIVATIVES RISK: Investments in derivatives may be illiquid, difficult to price, and leveraged so that small changes may produce disproportionate losses for the Portfolio, and may be subject to counterparty risk to a greater degree than more traditional investments.

• MANAGEMENT RISK: The Portfolio 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.

As with all investments, you may lose money by investing in the Portfolio.

BAR CHART AND PERFORMANCE INFORMATION:

The bar chart and performance information provide an indication of the historical risk of an investment in the Portfolio by showing:

• how the Portfolio's performance changed over the life of the Portfolio; and

• how the Portfolio'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 Portfolio's website at www.AllianceBernstein.com (click on "Individuals—U.S." then "Products & Performance").

The Portfolio's past performance before and after taxes, of course, does not necessarily indicate how it will perform in the future.

Bar Chart

The annual returns in the bar chart is 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.

Calendar Year End (%)

During the period shown in the bar chart, the Portfolio's:

BEST QUARTER WAS UP 6.20%, 2ND QUARTER, 2011; AND WORST QUARTER WAS DOWN -0.81%, 1ST QUARTER, 2011.

Performance Table
Average Annual Total Returns
(For the periods ended December 31, 2012)

Average Annual Total Returns AllianceBernstein High Income Municipal Portfolio		1 YEAR	SINCE INCEPTION		INCEPTION DATE
CLASS A	[1]	13.13%	9.70%	[2]	Jan. 26, 2010
CLASS A Return After Taxes on Distributions	[1]	13.03%	9.52%	[2]	Jan. 26, 2010
CLASS A Return After Taxes on Distributions and Sale of Portfolio Shares	[1]	10.26%	8.91%	[2]	Jan. 26, 2010
CLASS C		14.91%	10.09%	[2]	Jan. 26, 2010
ADVISOR CLASS		16.98%	11.16%	[2]	Jan. 26, 2010
Barclays Municipal Bond Index (reflects no deduction for fees, expenses or taxes)		6.78%	6.52%	[2]	Jan. 26, 2010

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

[1] Including Interest Expense Before Waiver

[2] The fee waiver and/or expense reimbursement agreement will remain in effect until January 31, 2014 and will be automatically extended for one-year terms thereafter unless terminated by the Adviser upon 60 days' notice to the Portfolio prior to that date.

[3] Including Interest Expense After Fee Waiver and/or Expense Reimbursement

[4] If interest expense were excluded, net expenses would be as follows: Class A Class C Advisor Class ---------- .80% 1.50% .50%

[1] Assuming redemption at the end of the period, a 1% CDSC would increase expenses by approximately $100.

[1] After-tax Returns: -Are shown for Class A shares only and will vary for Class C shares because Class C shares have higher expense ratios; -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.

[2] Inception date for all Classes: 1/26/2010.