| Form N-CSR Cover | 6 Months Ended |
| Nov. 30, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | AB MUNICIPAL INCOME FUND, INC. |
| Entity Central Index Key | 0000798737 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Nov. 30, 2024 |
| Shareholder Report | 6 Months Ended |
| Nov. 30, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | AB MUNICIPAL INCOME FUND, INC. |
| Entity Central Index Key | 0000798737 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | Nov. 30, 2024 |
| C000069624 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB California Portfolio |
| Class Name | Advisor Class |
| Trading Symbol | ALCVX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB California Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALCVX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ALCVX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Advisor Class $26 0.50% |
| Expenses Paid, Amount | $ 26 |
| Expense Ratio, Percent | 0.50% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Advisor Class Bloomberg Municipal Bond Index 11/14 $10,000 $10,000 05/15 $10,050 $10,071 05/16 $10,667 $10,662 05/17 $10,767 $10,818 05/18 $10,961 $10,938 05/19 $11,485 $11,639 05/20 $11,627 $12,102 05/21 $12,624 $12,675 05/22 $11,824 $11,814 05/23 $11,890 $11,872 05/24 $12,342 $12,189 11/24 $12,924 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Advisor Class 4.43 % 6.69 % 1.88 % 2.60 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 1,275,769,649 |
| Holdings Count | Holding | 406 |
| Advisory Fees Paid, Amount | $ 2,673,424 |
| InvestmentCompanyPortfolioTurnover | 17% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $1,275,769,649 # of Portfolio Holdings 406 Portfolio Turnover Rate 17% Total Advisory Fees Paid $2,673,424 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 4.4% AA 28.7% A 25.6% BBB 18.2% BB 5.0% B 0.5% A-1+ 3.0% SP-1+ 2.1% Pre-refunded 1.3% Not Rated 11.2% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000028619 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB California Portfolio |
| Class Name | Class A |
| Trading Symbol | ALCAX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB California Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALCAX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ALCAX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $38 0.75% |
| Expenses Paid, Amount | $ 38 |
| Expense Ratio, Percent | 0.75% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Class A (with sales charges) Bloomberg Municipal Bond Index 11/14 $9,703 $10,000 05/15 $9,738 $10,071 05/16 $10,310 $10,662 05/17 $10,381 $10,818 05/18 $10,542 $10,938 05/19 $11,021 $11,639 05/20 $11,127 $12,102 05/21 $12,051 $12,675 05/22 $11,259 $11,814 05/23 $11,293 $11,872 05/24 $11,696 $12,189 11/24 $12,229 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Class A (without sales charges) 4.30 % 6.41 % 1.63 % 2.34 % Class A (with sales charges) 1.18 % 3.22 % 1.01 % 2.03 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 1,275,769,649 |
| Holdings Count | Holding | 406 |
| Advisory Fees Paid, Amount | $ 2,673,424 |
| InvestmentCompanyPortfolioTurnover | 17% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $1,275,769,649 # of Portfolio Holdings 406 Portfolio Turnover Rate 17% Total Advisory Fees Paid $2,673,424 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 4.4% AA 28.7% A 25.6% BBB 18.2% BB 5.0% B 0.5% A-1+ 3.0% SP-1+ 2.1% Pre-refunded 1.3% Not Rated 11.2% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000028621 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB California Portfolio |
| Class Name | Class C |
| Trading Symbol | ACACX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB California Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ACACX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ACACX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $77 1.50% |
| Expenses Paid, Amount | $ 77 |
| Expense Ratio, Percent | 1.50% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Class C Bloomberg Municipal Bond Index 11/14 $10,000 $10,000 05/15 $10,009 $10,071 05/16 $10,518 $10,662 05/17 $10,502 $10,818 05/18 $10,584 $10,938 05/19 $11,000 $11,639 05/20 $11,015 $12,102 05/21 $11,831 $12,675 05/22 $10,980 $11,814 05/23 $10,921 $11,872 05/24 $11,232 $12,189 11/24 $11,704 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Class C (without sales charges) 4.00 % 5.62 % 0.87 % 1.59 % Class C (with sales charges) 3.00 % 4.62 % 0.87 % 1.59 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 1,275,769,649 |
| Holdings Count | Holding | 406 |
| Advisory Fees Paid, Amount | $ 2,673,424 |
| InvestmentCompanyPortfolioTurnover | 17% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $1,275,769,649 # of Portfolio Holdings 406 Portfolio Turnover Rate 17% Total Advisory Fees Paid $2,673,424 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 4.4% AA 28.7% A 25.6% BBB 18.2% BB 5.0% B 0.5% A-1+ 3.0% SP-1+ 2.1% Pre-refunded 1.3% Not Rated 11.2% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000082629 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB High Income Municipal Portfolio |
| Class Name | Advisor Class |
| Trading Symbol | ABTYX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB High Income Municipal Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ABTYX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ABTYX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Advisor Class $44 0.84% |
| Expenses Paid, Amount | $ 44 |
| Expense Ratio, Percent | 0.84% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Advisor Class Bloomberg Municipal Bond Index 11/14 $10,000 $10,000 05/15 $10,220 $10,071 05/16 $11,140 $10,662 05/17 $11,294 $10,818 05/18 $11,833 $10,938 05/19 $12,620 $11,639 05/20 $12,317 $12,102 05/21 $14,373 $12,675 05/22 $13,290 $11,814 05/23 $12,836 $11,872 05/24 $13,287 $12,189 11/24 $14,276 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Advisor Class 7.06 % 11.18 % 1.74 % 3.62 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 3,071,862,541 |
| Holdings Count | Holding | 838 |
| Advisory Fees Paid, Amount | $ 7,352,054 |
| InvestmentCompanyPortfolioTurnover | 9% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $3,071,862,541 # of Portfolio Holdings 838 Portfolio Turnover Rate 9% Total Advisory Fees Paid $7,352,054 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 1.4% AA 12.7% A 15.0% BBB 14.7% BB 9.2% B 1.4% CCC 0.3% Not Rated 45.3% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000082627 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB High Income Municipal Portfolio |
| Class Name | Class A |
| Trading Symbol | ABTHX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB High Income Municipal Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ABTHX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ABTHX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $57 1.09% |
| Expenses Paid, Amount | $ 57 |
| Expense Ratio, Percent | 1.09% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Class A (with sales charges) Bloomberg Municipal Bond Index 11/14 $9,698 $10,000 05/15 $9,889 $10,071 05/16 $10,761 $10,662 05/17 $10,883 $10,818 05/18 $11,373 $10,938 05/19 $12,091 $11,639 05/20 $11,768 $12,102 05/21 $13,699 $12,675 05/22 $12,646 $11,814 05/23 $12,184 $11,872 05/24 $12,583 $12,189 11/24 $13,486 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Class A (without sales charges) 6.82 % 10.90 % 1.47 % 3.35 % Class A (with sales charges) 3.64 % 7.54 % 0.84 % 3.04 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 3,071,862,541 |
| Holdings Count | Holding | 838 |
| Advisory Fees Paid, Amount | $ 7,352,054 |
| InvestmentCompanyPortfolioTurnover | 9% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $3,071,862,541 # of Portfolio Holdings 838 Portfolio Turnover Rate 9% Total Advisory Fees Paid $7,352,054 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 1.4% AA 12.7% A 15.0% BBB 14.7% BB 9.2% B 1.4% CCC 0.3% Not Rated 45.3% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000082628 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB High Income Municipal Portfolio |
| Class Name | Class C |
| Trading Symbol | ABTFX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB High Income Municipal Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ABTFX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ABTFX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $95 1.84% |
| Expenses Paid, Amount | $ 95 |
| Expense Ratio, Percent | 1.84% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Class C Bloomberg Municipal Bond Index 11/14 $10,000 $10,000 05/15 $10,169 $10,071 05/16 $10,975 $10,662 05/17 $11,016 $10,818 05/18 $11,437 $10,938 05/19 $12,076 $11,639 05/20 $11,659 $12,102 05/21 $13,471 $12,675 05/22 $12,331 $11,814 05/23 $11,790 $11,872 05/24 $12,092 $12,189 11/24 $12,916 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Class C (without sales charges) 6.53 % 10.07 % 0.72 % 2.59 % Class C (with sales charges) 5.53 % 9.07 % 0.72 % 2.59 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 3,071,862,541 |
| Holdings Count | Holding | 838 |
| Advisory Fees Paid, Amount | $ 7,352,054 |
| InvestmentCompanyPortfolioTurnover | 9% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $3,071,862,541 # of Portfolio Holdings 838 Portfolio Turnover Rate 9% Total Advisory Fees Paid $7,352,054 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 1.4% AA 12.7% A 15.0% BBB 14.7% BB 9.2% B 1.4% CCC 0.3% Not Rated 45.3% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000206561 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB High Income Municipal Portfolio |
| Class Name | Class Z |
| Trading Symbol | ABTZX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB High Income Municipal Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ABTZX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ABTZX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class Z $44 0.84% |
| Expenses Paid, Amount | $ 44 |
| Expense Ratio, Percent | 0.84% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Class Z Bloomberg Municipal Bond Index 09/18 $10,000 $10,000 05/19 $10,625 $10,647 05/20 $10,382 $11,071 05/21 $12,115 $11,595 05/22 $11,204 $10,807 05/23 $10,823 $10,860 05/24 $11,192 $11,151 11/24 $12,025 $11,657 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years Since Inception 9/28/2018 Class Z 7.06 % 11.19 % 1.73 % 3.03 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.51 % |
| Performance Inception Date | Sep. 28, 2018 |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 3,071,862,541 |
| Holdings Count | Holding | 838 |
| Advisory Fees Paid, Amount | $ 7,352,054 |
| InvestmentCompanyPortfolioTurnover | 9% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $3,071,862,541 # of Portfolio Holdings 838 Portfolio Turnover Rate 9% Total Advisory Fees Paid $7,352,054 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 1.4% AA 12.7% A 15.0% BBB 14.7% BB 9.2% B 1.4% CCC 0.3% Not Rated 45.3% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000069625 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB National Portfolio |
| Class Name | Advisor Class |
| Trading Symbol | ALTVX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB National Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALTVX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ALTVX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Advisor Class $26 0.50% |
| Expenses Paid, Amount | $ 26 |
| Expense Ratio, Percent | 0.50% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Advisor Class Bloomberg Municipal Bond Index 11/14 $10,000 $10,000 05/15 $10,067 $10,071 05/16 $10,732 $10,662 05/17 $10,865 $10,818 05/18 $11,053 $10,938 05/19 $11,631 $11,639 05/20 $11,783 $12,102 05/21 $12,757 $12,675 05/22 $11,964 $11,814 05/23 $11,910 $11,872 05/24 $12,294 $12,189 11/24 $12,888 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Advisor Class 4.52 % 6.56 % 1.58 % 2.57 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 2,029,411,119 |
| Holdings Count | Holding | 749 |
| Advisory Fees Paid, Amount | $ 4,123,957 |
| InvestmentCompanyPortfolioTurnover | 13% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $2,029,411,119 # of Portfolio Holdings 749 Portfolio Turnover Rate 13% Total Advisory Fees Paid $4,123,957 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 7.5% AA 32.2% A 27.4% BBB 14.3% BB 4.6% B 0.5% A-1+ 1.1% Pre-refunded 2.2% Not Rated 10.2% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000028628 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB National Portfolio |
| Class Name | Class A |
| Trading Symbol | ALTHX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB National Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALTHX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ALTHX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $38 0.75% |
| Expenses Paid, Amount | $ 38 |
| Expense Ratio, Percent | 0.75% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Class A (with sales charges) Bloomberg Municipal Bond Index 11/14 $9,700 $10,000 05/15 $9,742 $10,071 05/16 $10,370 $10,662 05/17 $10,473 $10,818 05/18 $10,627 $10,938 05/19 $11,158 $11,639 05/20 $11,273 $12,102 05/21 $12,175 $12,675 05/22 $11,389 $11,814 05/23 $11,309 $11,872 05/24 $11,647 $12,189 11/24 $12,191 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Class A (without sales charges) 4.39 % 6.29 % 1.33 % 2.31 % Class A (with sales charges) 1.21 % 3.15 % 0.72 % 2.00 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 2,029,411,119 |
| Holdings Count | Holding | 749 |
| Advisory Fees Paid, Amount | $ 4,123,957 |
| InvestmentCompanyPortfolioTurnover | 13% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $2,029,411,119 # of Portfolio Holdings 749 Portfolio Turnover Rate 13% Total Advisory Fees Paid $4,123,957 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 7.5% AA 32.2% A 27.4% BBB 14.3% BB 4.6% B 0.5% A-1+ 1.1% Pre-refunded 2.2% Not Rated 10.2% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000028630 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB National Portfolio |
| Class Name | Class C |
| Trading Symbol | ALNCX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB National Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALNCX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ALNCX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $77 1.50% |
| Expenses Paid, Amount | $ 77 |
| Expense Ratio, Percent | 1.50% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Class C Bloomberg Municipal Bond Index 11/14 $10,000 $10,000 05/15 $10,007 $10,071 05/16 $10,573 $10,662 05/17 $10,598 $10,818 05/18 $10,675 $10,938 05/19 $11,132 $11,639 05/20 $11,156 $12,102 05/21 $11,959 $12,675 05/22 $11,103 $11,814 05/23 $10,942 $11,872 05/24 $11,192 $12,189 11/24 $11,665 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Class C (without sales charges) 4.01 % 5.62 % 0.57 % 1.55 % Class C (with sales charges) 3.01 % 4.62 % 0.57 % 1.55 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 2,029,411,119 |
| Holdings Count | Holding | 749 |
| Advisory Fees Paid, Amount | $ 4,123,957 |
| InvestmentCompanyPortfolioTurnover | 13% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $2,029,411,119 # of Portfolio Holdings 749 Portfolio Turnover Rate 13% Total Advisory Fees Paid $4,123,957 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 7.5% AA 32.2% A 27.4% BBB 14.3% BB 4.6% B 0.5% A-1+ 1.1% Pre-refunded 2.2% Not Rated 10.2% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000069626 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB New York Portfolio |
| Class Name | Advisor Class |
| Trading Symbol | ALNVX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB New York Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALNVX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ALNVX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Advisor Class $26 0.50% |
| Expenses Paid, Amount | $ 26 |
| Expense Ratio, Percent | 0.50% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Advisor Class Bloomberg Municipal Bond Index 11/14 $10,000 $10,000 05/15 $10,104 $10,071 05/16 $10,726 $10,662 05/17 $10,861 $10,818 05/18 $10,991 $10,938 05/19 $11,581 $11,639 05/20 $11,532 $12,102 05/21 $12,616 $12,675 05/22 $11,852 $11,814 05/23 $11,779 $11,872 05/24 $12,133 $12,189 11/24 $12,713 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Advisor Class 4.50 % 6.86 % 1.40 % 2.43 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 512,074,709 |
| Holdings Count | Holding | 227 |
| Advisory Fees Paid, Amount | $ 959,985 |
| InvestmentCompanyPortfolioTurnover | 16% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $512,074,709 # of Portfolio Holdings 227 Portfolio Turnover Rate 16% Total Advisory Fees Paid $959,985 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 6.0% AA 32.8% A 17.4% BBB 26.8% BB 5.1% B 1.8% CCC 0.6% A-1+ 0.3% A-1 0.4% Pre-refunded 2.9% Not Rated 5.9% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000028631 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB New York Portfolio |
| Class Name | Class A |
| Trading Symbol | ALNYX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB New York Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALNYX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ALNYX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class A $38 0.75% |
| Expenses Paid, Amount | $ 38 |
| Expense Ratio, Percent | 0.75% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Class A (with sales charges) Bloomberg Municipal Bond Index 11/14 $9,699 $10,000 05/15 $9,787 $10,071 05/16 $10,374 $10,662 05/17 $10,478 $10,818 05/18 $10,578 $10,938 05/19 $11,120 $11,639 05/20 $11,043 $12,102 05/21 $12,052 $12,675 05/22 $11,293 $11,814 05/23 $11,196 $11,872 05/24 $11,506 $12,189 11/24 $12,037 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Class A (without sales charges) 4.36 % 6.70 % 1.16 % 2.18 % Class A (with sales charges) 1.27 % 3.51 % 0.56 % 1.87 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 512,074,709 |
| Holdings Count | Holding | 227 |
| Advisory Fees Paid, Amount | $ 959,985 |
| InvestmentCompanyPortfolioTurnover | 16% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $512,074,709 # of Portfolio Holdings 227 Portfolio Turnover Rate 16% Total Advisory Fees Paid $959,985 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 6.0% AA 32.8% A 17.4% BBB 26.8% BB 5.1% B 1.8% CCC 0.6% A-1+ 0.3% A-1 0.4% Pre-refunded 2.9% Not Rated 5.9% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| C000028633 | |
| Shareholder Report [Line Items] | |
| Fund Name | AB New York Portfolio |
| Class Name | Class C |
| Trading Symbol | ANYCX |
| Annual or Semi-Annual Statement [Text Block] | This semi-annual shareholder report contains important information about the AB New York Portfolio (the “Portfolio”) for the period of June 1, 2024 to November 30, 2024. |
| Shareholder Report Annual or Semi-Annual | Semi-Annual Shareholder Report |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ANYCX-S. You can also request this information by contacting us at (800) 227 4618. |
| Additional Information Phone Number | (800) 227 4618 |
| Additional Information Website | https://www.abfunds.com/link/AB/ANYCX-S |
| Expenses [Text Block] | What were the Fund costs for the last six months? (Based on a hypothetical $10,000 investment) Class Name Cost of a $10,000 investment Costs paid as a percentage of a $10,000 investment Class C $77 1.50% |
| Expenses Paid, Amount | $ 77 |
| Expense Ratio, Percent | 1.50% |
| Performance Past Does Not Indicate Future [Text] | The Fund’s past performance is not a good predictor of the Fund’s future performance. |
| Line Graph [Table Text Block] | Fund Performance The following graph shows the performance of hypothetical $10,000 investments in the Fund and a broad-based securities market index over the most recently completed 10 fiscal years of the Fund, or since inception, if shorter. The Fund's performance reflects applicable sales charges and assumes the reinvestment of dividends. Class C Bloomberg Municipal Bond Index 11/14 $10,000 $10,000 05/15 $10,054 $10,071 05/16 $10,578 $10,662 05/17 $10,605 $10,818 05/18 $10,614 $10,938 05/19 $11,083 $11,639 05/20 $10,917 $12,102 05/21 $11,826 $12,675 05/22 $11,009 $11,814 05/23 $10,833 $11,872 05/24 $11,044 $12,189 11/24 $11,504 $12,743 |
| Average Annual Return [Table Text Block] | AATR 6 Months 1 Year 5 Years 10 Years Class C (without sales charges) 3.97 % 5.79 % 0.39 % 1.41 % Class C (with sales charges) 2.97 % 4.79 % 0.39 % 1.41 % Bloomberg Municipal Bond Index 4.54 % 4.93 % 1.35 % 2.45 % |
| No Deduction of Taxes [Text Block] | The graph and table do not reflect the deduction of taxes that a shareholder would pay on Fund distributions or the redemption or sale of Fund shares. |
| AssetsNet | $ 512,074,709 |
| Holdings Count | Holding | 227 |
| Advisory Fees Paid, Amount | $ 959,985 |
| InvestmentCompanyPortfolioTurnover | 16% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $512,074,709 # of Portfolio Holdings 227 Portfolio Turnover Rate 16% Total Advisory Fees Paid $959,985 |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference * Value Value AAA 6.0% AA 32.8% A 17.4% BBB 26.8% BB 5.1% B 1.8% CCC 0.6% A-1+ 0.3% A-1 0.4% Pre-refunded 2.9% Not Rated 5.9% Footnote Description Footnote * The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Credit Ratings Selection [Text Block] | The Fund’s quality rating breakdown is expressed as a percentage of the Fund’s total investments in municipal securities and may vary over time. The quality ratings are determined by using the S&P Global Ratings (“S&P”), Moody’s Investors Services, Inc. (“Moody’s”) and Fitch Ratings, Ltd. (“Fitch”). The Fund considers the credit ratings issued by S&P, Moody’s and Fitch and uses the highest rating issued by the agencies. These ratings are a measure of the quality and safety of a bond or portfolio, based on the issuer’s financial condition. AAA is the highest (best) and D is the lowest (worst). If applicable, the pre-refunded category includes bonds which are secured by U.S. Government securities and therefore are deemed high-quality investment grade by AllianceBernstein L.P. (the "Adviser"). If applicable, Not Applicable (N/A) includes non-credit worthy investments, such as equities, currency contracts, futures and options. If applicable, the Not Rated category includes bonds that are not rated by a nationally recognized statistical rating organization. The Adviser evaluates the creditworthiness of non-rated securities based on a number of factors including, but not limited to, cash flows, enterprise value and economic environment. |
| Shareholder Report, Line Graph (Details) - USD ($) | 6 Months Ended | ||||||||||||
| Nov. 30, 2024 | May 31, 2024 | May 31, 2023 | May 31, 2022 | May 31, 2021 | May 31, 2020 | May 31, 2019 | Sep. 27, 2018 | May 31, 2018 | May 31, 2017 | May 31, 2016 | May 31, 2015 | Nov. 30, 2014 | |
| C000069624 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Advisor Class | ||||||||||||
| Account Value | $ 12,924 | $ 12,342 | $ 11,890 | $ 11,824 | $ 12,624 | $ 11,627 | $ 11,485 | $ 10,961 | $ 10,767 | $ 10,667 | $ 10,050 | $ 10,000 | |
| C000028619 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Class A (with sales charges) | ||||||||||||
| Account Value | $ 12,229 | 11,696 | 11,293 | 11,259 | 12,051 | 11,127 | 11,021 | 10,542 | 10,381 | 10,310 | 9,738 | 9,703 | |
| C000028621 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Class C | ||||||||||||
| Account Value | $ 11,704 | 11,232 | 10,921 | 10,980 | 11,831 | 11,015 | 11,000 | 10,584 | 10,502 | 10,518 | 10,009 | 10,000 | |
| C000082629 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Advisor Class | ||||||||||||
| Account Value | $ 14,276 | 13,287 | 12,836 | 13,290 | 14,373 | 12,317 | 12,620 | 11,833 | 11,294 | 11,140 | 10,220 | 10,000 | |
| C000082627 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Class A (with sales charges) | ||||||||||||
| Account Value | $ 13,486 | 12,583 | 12,184 | 12,646 | 13,699 | 11,768 | 12,091 | 11,373 | 10,883 | 10,761 | 9,889 | 9,698 | |
| C000082628 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Class C | ||||||||||||
| Account Value | $ 12,916 | 12,092 | 11,790 | 12,331 | 13,471 | 11,659 | 12,076 | 11,437 | 11,016 | 10,975 | 10,169 | 10,000 | |
| C000206561 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Class Z | ||||||||||||
| Account Value | $ 12,025 | 11,192 | 10,823 | 11,204 | 12,115 | 10,382 | 10,625 | $ 10,000 | |||||
| C000069625 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Advisor Class | ||||||||||||
| Account Value | $ 12,888 | 12,294 | 11,910 | 11,964 | 12,757 | 11,783 | 11,631 | 11,053 | 10,865 | 10,732 | 10,067 | 10,000 | |
| C000028628 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Class A (with sales charges) | ||||||||||||
| Account Value | $ 12,191 | 11,647 | 11,309 | 11,389 | 12,175 | 11,273 | 11,158 | 10,627 | 10,473 | 10,370 | 9,742 | 9,700 | |
| C000028630 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Class C | ||||||||||||
| Account Value | $ 11,665 | 11,192 | 10,942 | 11,103 | 11,959 | 11,156 | 11,132 | 10,675 | 10,598 | 10,573 | 10,007 | 10,000 | |
| C000069626 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Advisor Class | ||||||||||||
| Account Value | $ 12,713 | 12,133 | 11,779 | 11,852 | 12,616 | 11,532 | 11,581 | 10,991 | 10,861 | 10,726 | 10,104 | 10,000 | |
| C000028631 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Class A (with sales charges) | ||||||||||||
| Account Value | $ 12,037 | 11,506 | 11,196 | 11,293 | 12,052 | 11,043 | 11,120 | 10,578 | 10,478 | 10,374 | 9,787 | 9,699 | |
| C000028633 | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Class C | ||||||||||||
| Account Value | $ 11,504 | 11,044 | 10,833 | 11,009 | 11,826 | 10,917 | 11,083 | 10,614 | 10,605 | 10,578 | 10,054 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 11,657 | 11,151 | 10,860 | 10,807 | 11,595 | 11,071 | 10,647 | $ 10,000 | |||||
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | 12,189 | 11,872 | 11,814 | 12,675 | 12,102 | 11,639 | 10,938 | 10,818 | 10,662 | 10,071 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||||||||||
| Account Value [Line Items] | |||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||
| Account Value | $ 12,743 | $ 12,189 | $ 11,872 | $ 11,814 | $ 12,675 | $ 12,102 | $ 11,639 | $ 10,938 | $ 10,818 | $ 10,662 | $ 10,071 | $ 10,000 |
| Shareholder Report, Average Annual Return (Details) | 6 Months Ended | 12 Months Ended | 60 Months Ended | 74 Months Ended | 120 Months Ended |
| Nov. 30, 2024 | Nov. 30, 2024 | Nov. 30, 2024 | Nov. 30, 2024 | Nov. 30, 2024 | |
| C000069624 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Advisor Class | ||||
| C000028619 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Class A (with sales charges) | ||||
| Average Annual Return, Percent | 1.18% | 3.22% | 1.01% | 2.03% | |
| C000028621 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Class C | ||||
| Average Annual Return, Percent | 3% | 4.62% | 0.87% | 1.59% | |
| C000082629 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Advisor Class | ||||
| C000082627 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Class A (with sales charges) | ||||
| Average Annual Return, Percent | 3.64% | 7.54% | 0.84% | 3.04% | |
| C000082628 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Class C | ||||
| Average Annual Return, Percent | 5.53% | 9.07% | 0.72% | 2.59% | |
| C000206561 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Class Z | ||||
| C000069625 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Advisor Class | ||||
| C000028628 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Class A (with sales charges) | ||||
| Average Annual Return, Percent | 1.21% | 3.15% | 0.72% | 2% | |
| C000028630 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Class C | ||||
| Average Annual Return, Percent | 3.01% | 4.62% | 0.57% | 1.55% | |
| C000069626 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Advisor Class | ||||
| C000028631 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Class A (with sales charges) | ||||
| Average Annual Return, Percent | 1.27% | 3.51% | 0.56% | 1.87% | |
| C000028633 | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Class C | ||||
| Average Annual Return, Percent | 2.97% | 4.79% | 0.39% | 1.41% | |
| Without Sales Load [Member] | C000069624 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.43% | 6.69% | 1.88% | 2.60% | |
| Without Sales Load [Member] | C000028619 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.30% | 6.41% | 1.63% | 2.34% | |
| Without Sales Load [Member] | C000028621 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4% | 5.62% | 0.87% | 1.59% | |
| Without Sales Load [Member] | C000082629 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 7.06% | 11.18% | 1.74% | 3.62% | |
| Without Sales Load [Member] | C000082627 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 6.82% | 10.90% | 1.47% | 3.35% | |
| Without Sales Load [Member] | C000082628 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 6.53% | 10.07% | 0.72% | 2.59% | |
| Without Sales Load [Member] | C000206561 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 7.06% | 11.19% | 1.73% | 3.03% | |
| Without Sales Load [Member] | C000069625 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.52% | 6.56% | 1.58% | 2.57% | |
| Without Sales Load [Member] | C000028628 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.39% | 6.29% | 1.33% | 2.31% | |
| Without Sales Load [Member] | C000028630 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.01% | 5.62% | 0.57% | 1.55% | |
| Without Sales Load [Member] | C000069626 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.50% | 6.86% | 1.40% | 2.43% | |
| Without Sales Load [Member] | C000028631 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.36% | 6.70% | 1.16% | 2.18% | |
| Without Sales Load [Member] | C000028633 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 3.97% | 5.79% | 0.39% | 1.41% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.51% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% | |
| AllianceBernstein Index: Bloomberg Municipal Bond | |||||
| Average Annual Return [Line Items] | |||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||
| Average Annual Return, Percent | 4.54% | 4.93% | 1.35% | 2.45% |
| Shareholder Report, Holdings (Details) | Nov. 30, 2024 |
| C000069624 | Credit Rating Other LineA-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3% |
| C000069624 | Credit Rating Other LineSP-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.10% |
| C000069624 | Credit Rating Other LinePre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| C000069624 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.20% |
| C000069624 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| C000069624 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 28.70% |
| C000069624 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 25.60% |
| C000069624 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 18.20% |
| C000069624 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5% |
| C000069624 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| C000028619 | Credit Rating Other LineA-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3% |
| C000028619 | Credit Rating Other LineSP-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.10% |
| C000028619 | Credit Rating Other LinePre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| C000028619 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.20% |
| C000028619 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| C000028619 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 28.70% |
| C000028619 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 25.60% |
| C000028619 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 18.20% |
| C000028619 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5% |
| C000028619 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| C000028621 | Credit Rating Other LineA-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3% |
| C000028621 | Credit Rating Other LineSP-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.10% |
| C000028621 | Credit Rating Other LinePre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| C000028621 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.20% |
| C000028621 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.40% |
| C000028621 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 28.70% |
| C000028621 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 25.60% |
| C000028621 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 18.20% |
| C000028621 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5% |
| C000028621 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| C000082629 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 45.30% |
| C000082629 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000082629 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.70% |
| C000082629 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15% |
| C000082629 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.70% |
| C000082629 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.20% |
| C000082629 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000082629 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000082627 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 45.30% |
| C000082627 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000082627 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.70% |
| C000082627 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15% |
| C000082627 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.70% |
| C000082627 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.20% |
| C000082627 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000082627 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000082628 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 45.30% |
| C000082628 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000082628 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.70% |
| C000082628 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15% |
| C000082628 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.70% |
| C000082628 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.20% |
| C000082628 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000082628 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000206561 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 45.30% |
| C000206561 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000206561 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.70% |
| C000206561 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15% |
| C000206561 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.70% |
| C000206561 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.20% |
| C000206561 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000206561 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000069625 | Credit Rating Other LineA-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.10% |
| C000069625 | Credit Rating Other LinePre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| C000069625 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.20% |
| C000069625 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.50% |
| C000069625 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 32.20% |
| C000069625 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 27.40% |
| C000069625 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.30% |
| C000069625 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000069625 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| C000028628 | Credit Rating Other LineA-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.10% |
| C000028628 | Credit Rating Other LinePre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| C000028628 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.20% |
| C000028628 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.50% |
| C000028628 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 32.20% |
| C000028628 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 27.40% |
| C000028628 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.30% |
| C000028628 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000028628 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| C000028630 | Credit Rating Other LineA-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.10% |
| C000028630 | Credit Rating Other LinePre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| C000028630 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.20% |
| C000028630 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 7.50% |
| C000028630 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 32.20% |
| C000028630 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 27.40% |
| C000028630 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 14.30% |
| C000028630 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000028630 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| C000069626 | Credit Rating Other LineA-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000069626 | Credit Rating Other LinePre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| C000069626 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.90% |
| C000069626 | Credit Rating Other LineA-1 | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000069626 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6% |
| C000069626 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 32.80% |
| C000069626 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.40% |
| C000069626 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.80% |
| C000069626 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.10% |
| C000069626 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| C000069626 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.60% |
| C000028631 | Credit Rating Other LineA-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000028631 | Credit Rating Other LinePre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| C000028631 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.90% |
| C000028631 | Credit Rating Other LineA-1 | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000028631 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6% |
| C000028631 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 32.80% |
| C000028631 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.40% |
| C000028631 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.80% |
| C000028631 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.10% |
| C000028631 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| C000028631 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.60% |
| C000028633 | Credit Rating Other LineA-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000028633 | Credit Rating Other LinePre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.90% |
| C000028633 | Credit Rating Other LineNot Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.90% |
| C000028633 | Credit Rating Other LineA-1 | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000028633 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6% |
| C000028633 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 32.80% |
| C000028633 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 17.40% |
| C000028633 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.80% |
| C000028633 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.10% |
| C000028633 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| C000028633 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.60% |
