| Form N-CSR Cover | 12 Months Ended |
| May 31, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| 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 | May 31, 2024 |
| Shareholder Report | 12 Months Ended | 68 Months Ended |
| May 31, 2024 USD ($) Holding | May 31, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | ||
| Document Type | N-CSR | |
| 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 | May 31, 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 annual shareholder report contains important information about the AB California Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALCVX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ALCVX-A</span>" id="sjs-B19"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ALCVX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $51 0.50% | |
| Expenses Paid, Amount | $ 51 | |
| Expense Ratio, Percent | 0.50% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes of the Fund outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within multi-family housing and private higher education contributed, while selection in the miscellaneous revenue and industry Industrial Development Revenue (“IDR”) detracted. The Fund used derivatives for hedging purposes in the form of inflation swaps, which had no material impact on performance, and interest rate swaps, which added to performance. Credit default swaps, used for hedging and investment purposes, had no material impact on performance. Municipal market data rate locks were used for investment purposes and added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B24"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Advisor Class Bloomberg Municipal Bond Index 05/14 $10,000 $10,000 05/15 $10,401 $10,318 05/16 $11,040 $10,924 05/17 $11,144 $11,083 05/18 $11,345 $11,207 05/19 $11,887 $11,925 05/20 $12,034 $12,399 05/21 $13,065 $12,986 05/22 $12,238 $12,104 05/23 $12,306 $12,163 05/24 $12,809 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Advisor Class (without sales charge) 4.09% 1.44% 2.51% Advisor Class (with sales charge) 4.09% 1.44% 2.51% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 1,158,512,886 | $ 1,158,512,886 |
| Holdings Count | Holding | 402 | 402 |
| Advisory Fees Paid, Amount | $ 4,587,920 | |
| InvestmentCompanyPortfolioTurnover | 23% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $1,158,512,886 # of Portfolio Holdings 402 Portfolio Turnover Rate 23% Total Advisory Fees Paid $4,587,920 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 6.7% AA 28.9% A 21.5% BBB 15.6% BB 5.7% B 0.6% A-1+ 1.5% SP-1+ 3.4% Pre-refunded 4.6% Not Rated 11.5% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB California Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALCAX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ALCAX-A</span>" id="sjs-B44"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ALCAX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $76 0.75% | |
| Expenses Paid, Amount | $ 76 | |
| Expense Ratio, Percent | 0.75% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes of the Fund outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within multi-family housing and private higher education contributed, while selection in the miscellaneous revenue and industry Industrial Development Revenue (“IDR”) detracted. The Fund used derivatives for hedging purposes in the form of inflation swaps, which had no material impact on performance, and interest rate swaps, which added to performance. Credit default swaps, used for hedging and investment purposes, had no material impact on performance. Municipal market data rate locks were used for investment purposes and added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B49"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Class A Bloomberg Municipal Bond Index 05/14 $9,698 $10,000 05/15 $10,059 $10,318 05/16 $10,650 $10,924 05/17 $10,723 $11,083 05/18 $10,889 $11,207 05/19 $11,384 $11,925 05/20 $11,493 $12,399 05/21 $12,448 $12,986 05/22 $11,630 $12,104 05/23 $11,666 $12,163 05/24 $12,112 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Class A (without sales charge) 3.82% 1.19% 2.25% Class A (with sales charge) 0.70% 0.57% 1.93% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 1,158,512,886 | $ 1,158,512,886 |
| Holdings Count | Holding | 402 | 402 |
| Advisory Fees Paid, Amount | $ 4,587,920 | |
| InvestmentCompanyPortfolioTurnover | 23% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $1,158,512,886 # of Portfolio Holdings 402 Portfolio Turnover Rate 23% Total Advisory Fees Paid $4,587,920 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 6.7% AA 28.9% A 21.5% BBB 15.6% BB 5.7% B 0.6% A-1+ 1.5% SP-1+ 3.4% Pre-refunded 4.6% Not Rated 11.5% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB California Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ACACX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ACACX-A</span>" id="sjs-B69"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ACACX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $152 1.50% | |
| Expenses Paid, Amount | $ 152 | |
| Expense Ratio, Percent | 1.50% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes of the Fund outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within multi-family housing and private higher education contributed, while selection in the miscellaneous revenue and industry Industrial Development Revenue (“IDR”) detracted. The Fund used derivatives for hedging purposes in the form of inflation swaps, which had no material impact on performance, and interest rate swaps, which added to performance. Credit default swaps, used for hedging and investment purposes, had no material impact on performance. Municipal market data rate locks were used for investment purposes and added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B74"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Class C Bloomberg Municipal Bond Index 05/14 $10,000 $10,000 05/15 $10,298 $10,318 05/16 $10,823 $10,924 05/17 $10,806 $11,083 05/18 $10,891 $11,207 05/19 $11,318 $11,925 05/20 $11,334 $12,399 05/21 $12,173 $12,986 05/22 $11,298 $12,104 05/23 $11,237 $12,163 05/24 $11,580 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Class C (without sales charge) 3.05% 0.41% 1.48% Class C (with sales charge) 2.05% 0.41% 1.48% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 1,158,512,886 | $ 1,158,512,886 |
| Holdings Count | Holding | 402 | 402 |
| Advisory Fees Paid, Amount | $ 4,587,920 | |
| InvestmentCompanyPortfolioTurnover | 23% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $1,158,512,886 # of Portfolio Holdings 402 Portfolio Turnover Rate 23% Total Advisory Fees Paid $4,587,920 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 6.7% AA 28.9% A 21.5% BBB 15.6% BB 5.7% B 0.6% A-1+ 1.5% SP-1+ 3.4% Pre-refunded 4.6% Not Rated 11.5% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB High Income Municipal Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ABTYX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ABTYX-A</span>" id="sjs-B94"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ABTYX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $97 0.95% | |
| Expenses Paid, Amount | $ 97 | |
| Expense Ratio, Percent | 0.95% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within housing and special tax contributed, while selection in the electric utility and utility Industrial Development Revenue (“IDR”) detracted. While the benchmark is fully invested in investment-grade securities, the Fund invests in below-investment-grade securities, which added over both periods. The Fund used derivatives for hedging purposes in the form of inflation swaps, which had no material impact on performance, and interest rate swaps, which added to performance. Credit default swaps, used for hedging and investment purposes, had no material impact on performance. Municipal market data rate locks were used for investment purposes and added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B99"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Advisor Class Bloomberg Municipal Bond Index 05/14 $10,000 $10,000 05/15 $10,644 $10,318 05/16 $11,602 $10,924 05/17 $11,763 $11,083 05/18 $12,323 $11,207 05/19 $13,143 $11,925 05/20 $12,827 $12,399 05/21 $14,969 $12,986 05/22 $13,841 $12,104 05/23 $13,368 $12,163 05/24 $13,887 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Advisor Class (without sales charge) 3.88% 1.04% 3.34% Advisor Class (with sales charge) 3.88% 1.04% 3.34% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 2,790,140,470 | $ 2,790,140,470 |
| Holdings Count | Holding | 812 | 812 |
| Advisory Fees Paid, Amount | $ 13,917,267 | |
| InvestmentCompanyPortfolioTurnover | 23% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $2,790,140,470 # of Portfolio Holdings 812 Portfolio Turnover Rate 23% Total Advisory Fees Paid $13,917,267 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 1.5% AA 10.9% A 13.9% BBB 13.7% BB 10.2% B 1.4% CCC 0.4% CC 0.2% Pre-refunded 0.7% Not rated 47.1% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB High Income Municipal Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ABTHX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ABTHX-A</span>" id="sjs-B119"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ABTHX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $122 1.20% | |
| Expenses Paid, Amount | $ 122 | |
| Expense Ratio, Percent | 1.20% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within housing and special tax contributed, while selection in the electric utility and utility Industrial Development Revenue (“IDR”) detracted. While the benchmark is fully invested in investment-grade securities, the Fund invests in below-investment-grade securities, which added over both periods. The Fund used derivatives for hedging purposes in the form of inflation swaps, which had no material impact on performance, and interest rate swaps, which added to performance. Credit default swaps, used for hedging and investment purposes, had no material impact on performance. Municipal market data rate locks were used for investment purposes and added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B124"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Class A Bloomberg Municipal Bond Index 05/14 $9,701 $10,000 05/15 $10,296 $10,318 05/16 $11,204 $10,924 05/17 $11,331 $11,083 05/18 $11,841 $11,207 05/19 $12,589 $11,925 05/20 $12,253 $12,399 05/21 $14,263 $12,986 05/22 $13,167 $12,104 05/23 $12,686 $12,163 05/24 $13,145 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Class A (without sales charge) 3.62% 0.81% 3.08% Class A (with sales charge) 0.55% 0.19% 2.77% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 2,790,140,470 | $ 2,790,140,470 |
| Holdings Count | Holding | 812 | 812 |
| Advisory Fees Paid, Amount | $ 13,917,267 | |
| InvestmentCompanyPortfolioTurnover | 23% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $2,790,140,470 # of Portfolio Holdings 812 Portfolio Turnover Rate 23% Total Advisory Fees Paid $13,917,267 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 1.5% AA 10.9% A 13.9% BBB 13.7% BB 10.2% B 1.4% CCC 0.4% CC 0.2% Pre-refunded 0.7% Not rated 47.1% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB High Income Municipal Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ABTFX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ABTFX-A</span>" id="sjs-B144"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ABTFX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $198 1.95% | |
| Expenses Paid, Amount | $ 198 | |
| Expense Ratio, Percent | 1.95% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within housing and special tax contributed, while selection in the electric utility and utility Industrial Development Revenue (“IDR”) detracted. While the benchmark is fully invested in investment-grade securities, the Fund invests in below-investment-grade securities, which added over both periods. The Fund used derivatives for hedging purposes in the form of inflation swaps, which had no material impact on performance, and interest rate swaps, which added to performance. Credit default swaps, used for hedging and investment purposes, had no material impact on performance. Municipal market data rate locks were used for investment purposes and added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B149"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Class C Bloomberg Municipal Bond Index 05/14 $10,000 $10,000 05/15 $10,538 $10,318 05/16 $11,373 $10,924 05/17 $11,416 $11,083 05/18 $11,851 $11,207 05/19 $12,514 $11,925 05/20 $12,082 $12,399 05/21 $13,959 $12,986 05/22 $12,778 $12,104 05/23 $12,218 $12,163 05/24 $12,565 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Class C (without sales charge) 2.84% 0.03% 2.31% Class C (with sales charge) 1.84% 0.03% 2.31% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 2,790,140,470 | $ 2,790,140,470 |
| Holdings Count | Holding | 812 | 812 |
| Advisory Fees Paid, Amount | $ 13,917,267 | |
| InvestmentCompanyPortfolioTurnover | 23% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $2,790,140,470 # of Portfolio Holdings 812 Portfolio Turnover Rate 23% Total Advisory Fees Paid $13,917,267 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 1.5% AA 10.9% A 13.9% BBB 13.7% BB 10.2% B 1.4% CCC 0.4% CC 0.2% Pre-refunded 0.7% Not rated 47.1% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB High Income Municipal Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ABTZX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ABTZX-A</span>" id="sjs-B169"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ABTZX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $97 0.95% | |
| Expenses Paid, Amount | $ 97 | |
| Expense Ratio, Percent | 0.95% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within housing and special tax contributed, while selection in the electric utility and utility Industrial Development Revenue (“IDR”) detracted. While the benchmark is fully invested in investment-grade securities, the Fund invests in below-investment-grade securities, which added over both periods. The Fund used derivatives for hedging purposes in the form of inflation swaps, which had no material impact on performance, and interest rate swaps, which added to performance. Credit default swaps, used for hedging and investment purposes, had no material impact on performance. Municipal market data rate locks were used for investment purposes and added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B174"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | 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 $11,232 $11,151 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years Since Inception 9/28/18 Class Z (without sales charge) 3.78% 1.05% 2.07% Class Z (with sales charge) 3.78% 1.05% 2.07% Bloomberg Municipal Bond Index 2.67% 0.93% 1.94% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 2,790,140,470 | $ 2,790,140,470 |
| Holdings Count | Holding | 812 | 812 |
| Advisory Fees Paid, Amount | $ 13,917,267 | |
| InvestmentCompanyPortfolioTurnover | 23% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $2,790,140,470 # of Portfolio Holdings 812 Portfolio Turnover Rate 23% Total Advisory Fees Paid $13,917,267 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 1.5% AA 10.9% A 13.9% BBB 13.7% BB 10.2% B 1.4% CCC 0.4% CC 0.2% Pre-refunded 0.7% Not rated 47.1% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB National Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALTVX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ALTVX-A</span>" id="sjs-B195"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ALTVX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $51 0.50% | |
| Expenses Paid, Amount | $ 51 | |
| Expense Ratio, Percent | 0.50% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes, except Class C, outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within special tax and multi-family housing contributed, while selection within senior living and industry Industrial Development Revenue (“IDR") detracted. The Fund used derivatives for hedging purposes in the form of inflation swaps, credit default swaps and municipal market data rate locks which had no material impact on performance. Interest rate swaps added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B200"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Advisor Class Bloomberg Municipal Bond Index 05/14 $10,000 $10,000 05/15 $10,350 $10,318 05/16 $11,033 $10,924 05/17 $11,171 $11,083 05/18 $11,364 $11,207 05/19 $11,958 $11,925 05/20 $12,114 $12,399 05/21 $13,116 $12,986 05/22 $12,300 $12,104 05/23 $12,245 $12,163 05/24 $12,677 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Advisor Class (without sales charge) 3.53% 1.12% 2.40% Advisor Class (with sales charge) 3.53% 1.12% 2.40% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 1,848,707,128 | $ 1,848,707,128 |
| Holdings Count | Holding | 694 | 694 |
| Advisory Fees Paid, Amount | $ 7,415,878 | |
| InvestmentCompanyPortfolioTurnover | 30% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $1,848,707,128 # of Portfolio Holdings 694 Portfolio Turnover Rate 30% Total Advisory Fees Paid $7,415,878 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 8.3% AA 35.7% A 26.9% BBB 11.3% BB 4.8% B 0.4% CCC 0.1% D 0.1% A-1+ 0.3% SP-1+ 0.4% SP-1 0.1% Pre-refunded 1.0% Not Rated 10.6% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB National Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALTHX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ALTHX-A</span>" id="sjs-B220"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ALTHX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $76 0.75% | |
| Expenses Paid, Amount | $ 76 | |
| Expense Ratio, Percent | 0.75% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes, except Class C, outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within special tax and multi-family housing contributed, while selection within senior living and industry Industrial Development Revenue (“IDR") detracted. The Fund used derivatives for hedging purposes in the form of inflation swaps, credit default swaps and municipal market data rate locks which had no material impact on performance. Interest rate swaps added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B225"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Class A Bloomberg Municipal Bond Index 05/14 $9,697 $10,000 05/15 $9,998 $10,318 05/16 $10,642 $10,924 05/17 $10,748 $11,083 05/18 $10,907 $11,207 05/19 $11,451 $11,925 05/20 $11,569 $12,399 05/21 $12,495 $12,986 05/22 $11,688 $12,104 05/23 $11,607 $12,163 05/24 $11,986 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Class A (without sales charge) 3.27% 0.87% 2.14% Class A (with sales charge) 0.21% 0.26% 1.83% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 1,848,707,128 | $ 1,848,707,128 |
| Holdings Count | Holding | 694 | 694 |
| Advisory Fees Paid, Amount | $ 7,415,878 | |
| InvestmentCompanyPortfolioTurnover | 30% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $1,848,707,128 # of Portfolio Holdings 694 Portfolio Turnover Rate 30% Total Advisory Fees Paid $7,415,878 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 8.3% AA 35.7% A 26.9% BBB 11.3% BB 4.8% B 0.4% CCC 0.1% D 0.1% A-1+ 0.3% SP-1+ 0.4% SP-1 0.1% Pre-refunded 1.0% Not Rated 10.6% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB National Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALNCX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ALNCX-A</span>" id="sjs-B245"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ALNCX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $152 1.50% | |
| Expenses Paid, Amount | $ 152 | |
| Expense Ratio, Percent | 1.50% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes, except Class C, outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within special tax and multi-family housing contributed, while selection within senior living and industry Industrial Development Revenue (“IDR") detracted. The Fund used derivatives for hedging purposes in the form of inflation swaps, credit default swaps and municipal market data rate locks which had no material impact on performance. Interest rate swaps added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B250"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Class C Bloomberg Municipal Bond Index 05/14 $10,000 $10,000 05/15 $10,238 $10,318 05/16 $10,817 $10,924 05/17 $10,843 $11,083 05/18 $10,921 $11,207 05/19 $11,388 $11,925 05/20 $11,413 $12,399 05/21 $12,235 $12,986 05/22 $11,358 $12,104 05/23 $11,194 $12,163 05/24 $11,474 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Class C (without sales charge) 2.50% 0.12% 1.38% Class C (with sales charge) 1.50% 0.12% 1.38% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 1,848,707,128 | $ 1,848,707,128 |
| Holdings Count | Holding | 694 | 694 |
| Advisory Fees Paid, Amount | $ 7,415,878 | |
| InvestmentCompanyPortfolioTurnover | 30% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $1,848,707,128 # of Portfolio Holdings 694 Portfolio Turnover Rate 30% Total Advisory Fees Paid $7,415,878 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 8.3% AA 35.7% A 26.9% BBB 11.3% BB 4.8% B 0.4% CCC 0.1% D 0.1% A-1+ 0.3% SP-1+ 0.4% SP-1 0.1% Pre-refunded 1.0% Not Rated 10.6% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB New York Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALNVX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ALNVX-A</span>" id="sjs-B270"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ALNVX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $51 0.50% | |
| Expenses Paid, Amount | $ 51 | |
| Expense Ratio, Percent | 0.50% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes, except Class C, outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within water and sewer and senior living contributed, while selection within toll roads and private higher education detracted. The Fund used derivatives for hedging purposes in the form of inflation swaps and credit default swaps, which had no material impact on performance. Interest rate swaps added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B275"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Advisor Class Bloomberg Municipal Bond Index 05/14 $10,000 $10,000 05/15 $10,327 $10,318 05/16 $10,962 $10,924 05/17 $11,099 $11,083 05/18 $11,233 $11,207 05/19 $11,835 $11,925 05/20 $11,785 $12,399 05/21 $12,893 $12,986 05/22 $12,112 $12,104 05/23 $12,038 $12,163 05/24 $12,433 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Advisor Class (without sales charge) 3.28% 0.94% 2.20% Advisor Class (with sales charge) 3.28% 0.94% 2.20% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 491,328,347 | $ 491,328,347 |
| Holdings Count | Holding | 222 | 222 |
| Advisory Fees Paid, Amount | $ 1,926,992 | |
| InvestmentCompanyPortfolioTurnover | 35% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $491,328,347 # of Portfolio Holdings 222 Portfolio Turnover Rate 35% Total Advisory Fees Paid $1,926,992 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 5.7% AA 30.7% A 20.6% BBB 26.7% BB 4.6% B 1.8% CCC 0.6% CC 0.5% A-1+ 0.3% Pre-refunded 2.7% Not Rated 5.8% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB New York Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ALNYX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ALNYX-A</span>" id="sjs-B295"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ALNYX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $76 0.75% | |
| Expenses Paid, Amount | $ 76 | |
| Expense Ratio, Percent | 0.75% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes, except Class C, outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within water and sewer and senior living contributed, while selection within toll roads and private higher education detracted. The Fund used derivatives for hedging purposes in the form of inflation swaps and credit default swaps, which had no material impact on performance. Interest rate swaps added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B300"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Class A Bloomberg Municipal Bond Index 05/14 $9,698 $10,000 05/15 $9,977 $10,318 05/16 $10,575 $10,924 05/17 $10,681 $11,083 05/18 $10,782 $11,207 05/19 $11,335 $11,925 05/20 $11,257 $12,399 05/21 $12,285 $12,986 05/22 $11,511 $12,104 05/23 $11,413 $12,163 05/24 $11,757 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Class A (without sales charge) 3.02% 0.69% 1.94% Class A (with sales charge) -0.04% 0.08% 1.63% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 491,328,347 | $ 491,328,347 |
| Holdings Count | Holding | 222 | 222 |
| Advisory Fees Paid, Amount | $ 1,926,992 | |
| InvestmentCompanyPortfolioTurnover | 35% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $491,328,347 # of Portfolio Holdings 222 Portfolio Turnover Rate 35% Total Advisory Fees Paid $1,926,992 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 5.7% AA 30.7% A 20.6% BBB 26.7% BB 4.6% B 1.8% CCC 0.6% CC 0.5% A-1+ 0.3% Pre-refunded 2.7% Not Rated 5.8% * | |
| Material Fund Change [Text Block] | ||
| 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 annual shareholder report contains important information about the AB New York Portfolio (the “Fund”) for the period of June 1, 2023 to May 31, 2024. | |
| Shareholder Report Annual or Semi-Annual | Annual Shareholder Report | |
| Additional Information [Text Block] | You can find additional information about the Fund at https://www.abfunds.com/link/AB/ANYCX-A | |
| Additional Information Phone Number | (800) 227 4618 | |
| Additional Information Website | https://www.abfunds.com/link/AB/ANYCX-A</span>" id="sjs-B320"><span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">https://www.abfunds.com/link/AB/ANYCX-A</span> | |
| Expenses [Text Block] | What were the Fund costs for the last year? (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 $152 1.50% | |
| Expenses Paid, Amount | $ 152 | |
| Expense Ratio, Percent | 1.50% | |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? What affected the Fund’s performance? For the 12-month period, all share classes, except Class C, outperformed the Bloomberg Municipal Bond Index, before sales charges. Sector and security selection, as well as an overweight to credit, contributed to performance, relative to the benchmark. Security selection within water and sewer and senior living contributed, while selection within toll roads and private higher education detracted. The Fund used derivatives for hedging purposes in the form of inflation swaps and credit default swaps, which had no material impact on performance. Interest rate swaps added to overall performance. | |
| Performance Past Does Not Indicate Future [Text] | <span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p>" id="sjs-B325"><p style="line-height: 15.6px; box-sizing: border-box; color: rgb(0, 0, 0); display: block; flex-wrap: nowrap; font-size: 12px; font-weight: 400; grid-area: auto; margin: 0px; overflow: visible; text-align: left;"><span style="font-weight: 700; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; grid-area: auto; line-height: 15.6px; margin: 0px; overflow: visible; text-align: left;">The Fund’s past performance is not a good predictor of the Fund’s future performance.</span></p> | |
| Line Graph [Table Text Block] | Class C Bloomberg Municipal Bond Index 05/14 $10,000 $10,000 05/15 $10,225 $10,318 05/16 $10,757 $10,924 05/17 $10,784 $11,083 05/18 $10,794 $11,207 05/19 $11,270 $11,925 05/20 $11,102 $12,399 05/21 $12,026 $12,986 05/22 $11,195 $12,104 05/23 $11,016 $12,163 05/24 $11,251 $12,488 | |
| Average Annual Return [Table Text Block] | 1 Year 5 Years 10 Years Class C (without sales charge) 2.13% - 1.19% Class C (with sales charge) 1.13% -0.07% 1.19% Bloomberg Municipal Bond Index 2.67% 0.93% 2.25% | |
| 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 redemption of Fund shares. | |
| AssetsNet | $ 491,328,347 | $ 491,328,347 |
| Holdings Count | Holding | 222 | 222 |
| Advisory Fees Paid, Amount | $ 1,926,992 | |
| InvestmentCompanyPortfolioTurnover | 35% | |
| Additional Fund Statistics [Text Block] | Key Fund Statistics Net Assets $491,328,347 # of Portfolio Holdings 222 Portfolio Turnover Rate 35% Total Advisory Fees Paid $1,926,992 | |
| Holdings [Text Block] | Credit Rating Breakdown Footnote Reference Value Value AAA 5.7% AA 30.7% A 20.6% BBB 26.7% BB 4.6% B 1.8% CCC 0.6% CC 0.5% A-1+ 0.3% Pre-refunded 2.7% Not Rated 5.8% * | |
| Material Fund Change [Text Block] |
| Shareholder Report, Line Graph (Details) - USD ($) | 12 Months Ended | |||||||||||
| 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 | May 31, 2014 | |
| C000069624 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Advisor Class | |||||||||||
| Account Value | $ 12,809 | $ 12,306 | $ 12,238 | $ 13,065 | $ 12,034 | $ 11,887 | $ 11,345 | $ 11,144 | $ 11,040 | $ 10,401 | $ 10,000 | |
| C000028619 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class A | |||||||||||
| Account Value | $ 12,112 | 11,666 | 11,630 | 12,448 | 11,493 | 11,384 | 10,889 | 10,723 | 10,650 | 10,059 | 9,698 | |
| C000028621 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class C | |||||||||||
| Account Value | $ 11,580 | 11,237 | 11,298 | 12,173 | 11,334 | 11,318 | 10,891 | 10,806 | 10,823 | 10,298 | 10,000 | |
| C000082629 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Advisor Class | |||||||||||
| Account Value | $ 13,887 | 13,368 | 13,841 | 14,969 | 12,827 | 13,143 | 12,323 | 11,763 | 11,602 | 10,644 | 10,000 | |
| C000082627 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class A | |||||||||||
| Account Value | $ 13,145 | 12,686 | 13,167 | 14,263 | 12,253 | 12,589 | 11,841 | 11,331 | 11,204 | 10,296 | 9,701 | |
| C000082628 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class C | |||||||||||
| Account Value | $ 12,565 | 12,218 | 12,778 | 13,959 | 12,082 | 12,514 | 11,851 | 11,416 | 11,373 | 10,538 | 10,000 | |
| C000206561 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class Z | |||||||||||
| Account Value | $ 11,232 | 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 | $ 12,677 | 12,245 | 12,300 | 13,116 | 12,114 | 11,958 | 11,364 | 11,171 | 11,033 | 10,350 | 10,000 | |
| C000028628 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class A | |||||||||||
| Account Value | $ 11,986 | 11,607 | 11,688 | 12,495 | 11,569 | 11,451 | 10,907 | 10,748 | 10,642 | 9,998 | 9,697 | |
| C000028630 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class C | |||||||||||
| Account Value | $ 11,474 | 11,194 | 11,358 | 12,235 | 11,413 | 11,388 | 10,921 | 10,843 | 10,817 | 10,238 | 10,000 | |
| C000069626 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Advisor Class | |||||||||||
| Account Value | $ 12,433 | 12,038 | 12,112 | 12,893 | 11,785 | 11,835 | 11,233 | 11,099 | 10,962 | 10,327 | 10,000 | |
| C000028631 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class A | |||||||||||
| Account Value | $ 11,757 | 11,413 | 11,511 | 12,285 | 11,257 | 11,335 | 10,782 | 10,681 | 10,575 | 9,977 | 9,698 | |
| C000028633 | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class C | |||||||||||
| Account Value | $ 11,251 | 11,016 | 11,195 | 12,026 | 11,102 | 11,270 | 10,794 | 10,784 | 10,757 | 10,225 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 11,151 | 10,860 | 10,807 | 11,595 | 11,071 | 10,647 | $ 10,000 | |||||
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | 12,163 | 12,104 | 12,986 | 12,399 | 11,925 | 11,207 | 11,083 | 10,924 | 10,318 | 10,000 | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | $ 12,163 | $ 12,104 | $ 12,986 | $ 12,399 | $ 11,925 | $ 11,207 | $ 11,083 | $ 10,924 | $ 10,318 | $ 10,000 |
| Shareholder Report, Average Annual Return (Details) | 12 Months Ended | 60 Months Ended | 68 Months Ended | 120 Months Ended |
| May 31, 2024 | May 31, 2024 | May 31, 2024 | May 31, 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 | |||
| C000028621 | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Class C | |||
| 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 | |||
| C000082628 | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Class C | |||
| 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 | |||
| C000028630 | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Class C | |||
| 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 | |||
| C000028633 | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Class C | |||
| Without Sales Load [Member] | C000069624 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 4.09% | 1.44% | 2.51% | |
| Without Sales Load [Member] | C000028619 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 3.82% | 1.19% | 2.25% | |
| Without Sales Load [Member] | C000028621 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 3.05% | 0.41% | 1.48% | |
| Without Sales Load [Member] | C000082629 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 3.88% | 1.04% | 3.34% | |
| Without Sales Load [Member] | C000082627 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 3.62% | 0.81% | 3.08% | |
| Without Sales Load [Member] | C000082628 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 2.84% | 0.03% | 2.31% | |
| Without Sales Load [Member] | C000206561 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 3.78% | 1.05% | 2.07% | |
| Without Sales Load [Member] | C000069625 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 3.53% | 1.12% | 2.40% | |
| Without Sales Load [Member] | C000028628 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 3.27% | 0.87% | 2.14% | |
| Without Sales Load [Member] | C000028630 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 2.50% | 0.12% | 1.38% | |
| Without Sales Load [Member] | C000069626 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 3.28% | 0.94% | 2.20% | |
| Without Sales Load [Member] | C000028631 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 3.02% | 0.69% | 1.94% | |
| Without Sales Load [Member] | C000028633 | ||||
| Average Annual Return [Line Items] | ||||
| Average Annual Return, Percent | 2.13% | (0.07%) | 1.19% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 1.94% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |
| AllianceBernstein Index: Bloomberg Municipal Bond Index | ||||
| Average Annual Return [Line Items] | ||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% |
| Shareholder Report, Holdings (Details) | May 31, 2024 |
| C000069624 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.70% |
| C000069624 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 28.90% |
| C000069624 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.50% |
| C000069624 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.60% |
| C000069624 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| C000069624 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.60% |
| C000069624 | A-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.50% |
| C000069624 | SP-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.40% |
| C000069624 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000069624 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.50% |
| C000028619 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.70% |
| C000028619 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 28.90% |
| C000028619 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.50% |
| C000028619 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.60% |
| C000028619 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| C000028619 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.60% |
| C000028619 | A-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.50% |
| C000028619 | SP-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.40% |
| C000028619 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000028619 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.50% |
| C000028621 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 6.70% |
| C000028621 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 28.90% |
| C000028621 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.50% |
| C000028621 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.60% |
| C000028621 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| C000028621 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.60% |
| C000028621 | A-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.50% |
| C000028621 | SP-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.40% |
| C000028621 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000028621 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.50% |
| C000082629 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.50% |
| C000082629 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.90% |
| C000082629 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.90% |
| C000082629 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.70% |
| C000082629 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.20% |
| C000082629 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000082629 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.70% |
| C000082629 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000082629 | CC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000082629 | Not rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 47.10% |
| C000082627 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.50% |
| C000082627 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.90% |
| C000082627 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.90% |
| C000082627 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.70% |
| C000082627 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.20% |
| C000082627 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000082627 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.70% |
| C000082627 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000082627 | CC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000082627 | Not rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 47.10% |
| C000082628 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.50% |
| C000082628 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.90% |
| C000082628 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.90% |
| C000082628 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.70% |
| C000082628 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.20% |
| C000082628 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000082628 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.70% |
| C000082628 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000082628 | CC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000082628 | Not rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 47.10% |
| C000206561 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.50% |
| C000206561 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.90% |
| C000206561 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.90% |
| C000206561 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 13.70% |
| C000206561 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.20% |
| C000206561 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| C000206561 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.70% |
| C000206561 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000206561 | CC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.20% |
| C000206561 | Not rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 47.10% |
| C000069625 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| C000069625 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 35.70% |
| C000069625 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.90% |
| C000069625 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.30% |
| C000069625 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.80% |
| C000069625 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000069625 | A-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000069625 | SP-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000069625 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1% |
| C000069625 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.60% |
| C000069625 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000069625 | D | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000069625 | SP-1 | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000028628 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| C000028628 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 35.70% |
| C000028628 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.90% |
| C000028628 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.30% |
| C000028628 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.80% |
| C000028628 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000028628 | A-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000028628 | SP-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000028628 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1% |
| C000028628 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.60% |
| C000028628 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000028628 | D | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000028628 | SP-1 | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000028630 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| C000028630 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 35.70% |
| C000028630 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.90% |
| C000028630 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.30% |
| C000028630 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.80% |
| C000028630 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000028630 | A-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000028630 | SP-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.40% |
| C000028630 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1% |
| C000028630 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.60% |
| C000028630 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000028630 | D | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000028630 | SP-1 | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000069626 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| C000069626 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 30.70% |
| C000069626 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.60% |
| C000069626 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.70% |
| C000069626 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000069626 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| C000069626 | A-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000069626 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000069626 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| C000069626 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.60% |
| C000069626 | CC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| C000028631 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| C000028631 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 30.70% |
| C000028631 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.60% |
| C000028631 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.70% |
| C000028631 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000028631 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| C000028631 | A-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000028631 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000028631 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| C000028631 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.60% |
| C000028631 | CC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| C000028633 | AAA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.70% |
| C000028633 | AA | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 30.70% |
| C000028633 | A | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.60% |
| C000028633 | BBB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.70% |
| C000028633 | BB | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.60% |
| C000028633 | B | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| C000028633 | A-1+ | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.30% |
| C000028633 | Pre-refunded | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000028633 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.80% |
| C000028633 | CCC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.60% |
| C000028633 | CC | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
