| Form N-CSR Cover | 12 Months Ended |
| May 31, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | BlackRock California Municipal Series Trust |
| Entity Central Index Key | 0000765199 |
| Document Period End Date | May 31, 2024 |
| Shareholder Report | 12 Months Ended |
| May 31, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | BlackRock California Municipal Series Trust |
| Entity Central Index Key | 0000765199 |
| Document Period End Date | May 31, 2024 |
| C000011299 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | BlackRock California Municipal Opportunities Fund |
| Class Name | Investor A1 Shares |
| Trading Symbol | MDCMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock California Municipal Opportunities Fund (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 blackrock.com/fundreports . |
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period. |
| Additional Information Phone Number | (800) 441‑7762 |
| Additional Information Website | blackrock.com/fundreports |
| Expenses [Text Block] | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Class name Costs of a $10,000 Costs paid as a percentage of a Investor A1 Shares $ 0.61 % |
| Expenses Paid, Amount | $ 62 |
| Expense Ratio, Percent | 0.61% |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? The municipal bond market gained ground during the reporting period, with the benefit of income augmented by a modest gain in prices. Declining inflation fueled expectations that the U.S. Federal Reserve was set to begin cutting interest rates in 2024, benefiting the broader fixed-income market. Municipal bonds were further helped by positive economic growth, strong issuer fundamentals, and favorable supply-and-demand trends. What contributed to performance? The Fund’s positions in longer-duration and longer-maturity securities were notable contributors. (Duration is a measure of interest rate sensitivity.) The Fund’s holdings in corporate-backed municipals helped results, as did overweights in the utilities and pre-paid gas sectors. The Fund had an above-average weighting in cash, which had no material impact on results due to the attractive yields in this area. The Fund’s use of derivatives marginally contributed to performance. What detracted from performance? At a time of positive returns for the broader asset class, there were few meaningful detractors from Fund performance. With this said, its holdings in high-yield bonds—especially those with deep-discount structures—detracted given that yield spreads remained wide. Bonds issued by Puerto Rico Electric Power Authority were particularly notable detractors in this category due to continued uncertainty in the territory’s financial picture. The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results. |
| Performance Past Does Not Indicate Future [Text] | Past performance is not an indication of future results. |
| Line Graph [Table Text Block] | Fund performance Cumulative performance: June 1, 2014 through May 31, 2024 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance. |
| Average Annual Return [Table Text Block] | Average annual total returns 1 Year 5 Years 10 Years Investor A1 Shares 4.29 % 0.97 % 2.56 % Bloomberg Municipal Bond Index 2.67 % 0.93 % 2.25 % California Customized Reference Benchmark 3.04 % 0.88 % N/A |
| No Deduction of Taxes [Text Block] | Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. |
| Material Change Date | May 31, 2023 |
| Updated Performance Information Location [Text Block] | Visit blackrock.com |
| Net Assets | $ 2,285,640,268 |
| Holdings Count | Holding | 284 |
| Advisory Fees Paid, Amount | $ 8,253,931 |
| Investment Company Portfolio Turnover | 77% |
| Additional Fund Statistics [Text Block] | Key Fund statistics Net Assets $ % Number of Portfolio Holdings $ % Net Investment Advisory Fees $ % Portfolio Turnover Rate $ % |
| Holdings [Text Block] | What did the Fund invest in? (as of May 31, 2024) Sector allocation Sector (a)(b) Percent of Utilities 30.6 % County/City/Special District/School District 26.4 % Transportation 12.3 % Education 8.1 % Corporate 8.1 % Health 5.9 % State 5.9 % Tobacco 1.8 % Housing 0.9 % Credit quality allocation Credit Rating (a)(c) Percent of AAA/Aaa 18.3 % AA/Aa 52.5 % A 15.8 % BBB/Baa 3.1 % BB/Ba 0.2 % CCC/Caa 0.1 % N/R (d) 10.0 % (a) (b) (c) (d) Excludes short-term securities. (a) (b) (c) (d) For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes. (a) (b) (c) (d) For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. (a) (b) (c) (d) The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Quality Explanation [Text Block] | The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Ratings Selection [Text Block] | For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. |
| Material Fund Change [Text Block] | Material Fund changes This is a summary of certain changes to the Fund since May 31, 2023. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after May 31, 2024 at blackrock.com/fundreports The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Material Fund Change Expenses [Text Block] | The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Updated Prospectus Phone Number | (800) 441-7762 |
| Updated Prospectus Web Address | blackrock.com/fundreports |
| C000199773 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | BlackRock California Municipal Opportunities Fund |
| Class Name | Class K Shares |
| Trading Symbol | MKCMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock California Municipal Opportunities Fund (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 blackrock.com/fundreports . |
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period. |
| Additional Information Phone Number | (800) 441‑7762 |
| Additional Information Website | blackrock.com/fundreports |
| Expenses [Text Block] | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Class name Costs of a $10,000 Costs paid as a percentage of a Class K Shares $ 0.47 % |
| Expenses Paid, Amount | $ 48 |
| Expense Ratio, Percent | 0.47% |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? The municipal bond market gained ground during the reporting period, with the benefit of income augmented by a modest gain in prices. Declining inflation fueled expectations that the U.S. Federal Reserve was set to begin cutting interest rates in 2024, benefiting the broader fixed-income market. Municipal bonds were further helped by positive economic growth, strong issuer fundamentals, and favorable supply-and-demand trends. What contributed to performance? The Fund’s positions in longer-duration and longer-maturity securities were notable contributors. (Duration is a measure of interest rate sensitivity.) The Fund’s holdings in corporate-backed municipals helped results, as did overweights in the utilities and pre-paid gas sectors. The Fund had an above-average weighting in cash, which had no material impact on results due to the attractive yields in this area. The Fund’s use of derivatives marginally contributed to performance. What detracted from performance? At a time of positive returns for the broader asset class, there were few meaningful detractors from Fund performance. With this said, its holdings in high-yield bonds—especially those with deep-discount structures—detracted given that yield spreads remained wide. Bonds issued by Puerto Rico Electric Power Authority were particularly notable detractors in this category due to continued uncertainty in the territory’s financial picture. The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results. |
| Performance Past Does Not Indicate Future [Text] | Past performance is not an indication of future results. |
| Line Graph [Table Text Block] | Fund performance Cumulative performance: June 1, 2014 through May 31, 2024 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance. |
| Average Annual Return [Table Text Block] | Average annual total returns 1 Year 5 Years 10 Years Class K Shares 4.44 % 1.09 % 2.70 % Bloomberg Municipal Bond Index 2.67 % 0.93 % 2.25 % California Customized Reference Benchmark 3.04 % 0.88 % N/A |
| No Deduction of Taxes [Text Block] | Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. |
| Material Change Date | May 31, 2023 |
| Updated Performance Information Location [Text Block] | Visit blackrock.com |
| Net Assets | $ 2,285,640,268 |
| Holdings Count | Holding | 284 |
| Advisory Fees Paid, Amount | $ 8,253,931 |
| Investment Company Portfolio Turnover | 77% |
| Additional Fund Statistics [Text Block] | Key Fund statistics Net Assets $ % Number of Portfolio Holdings $ % Net Investment Advisory Fees $ % Portfolio Turnover Rate $ % |
| Holdings [Text Block] | What did the Fund invest in? (as of May 31, 2024) Sector allocation Sector (a)(b) Percent of Utilities 30.6 % County/City/Special District/School District 26.4 % Transportation 12.3 % Education 8.1 % Corporate 8.1 % Health 5.9 % State 5.9 % Tobacco 1.8 % Housing 0.9 % Credit quality allocation Credit Rating (a)(c) Percent of AAA/Aaa 18.3 % AA/Aa 52.5 % A 15.8 % BBB/Baa 3.1 % BB/Ba 0.2 % CCC/Caa 0.1 % N/R (d) 10.0 % (a) (b) (c) (d) Excludes short-term securities. (a) (b) (c) (d) For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes. (a) (b) (c) (d) For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. (a) (b) (c) (d) The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Quality Explanation [Text Block] | The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Ratings Selection [Text Block] | For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. |
| Material Fund Change [Text Block] | Material Fund changes This is a summary of certain changes to the Fund since May 31, 2023. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after May 31, 2024 at blackrock.com/fundreports The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Material Fund Change Expenses [Text Block] | The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Updated Prospectus Phone Number | (800) 441-7762 |
| Updated Prospectus Web Address | blackrock.com/fundreports |
| C000011302 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | BlackRock California Municipal Opportunities Fund |
| Class Name | Institutional Shares |
| Trading Symbol | MACMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock California Municipal Opportunities Fund (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 blackrock.com/fundreports . |
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period. |
| Additional Information Phone Number | (800) 441‑7762 |
| Additional Information Website | blackrock.com/fundreports |
| Expenses [Text Block] | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Class name Costs of a $10,000 Costs paid as a percentage of a Institutional Shares $ 0.52 % |
| Expenses Paid, Amount | $ 53 |
| Expense Ratio, Percent | 0.52% |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? The municipal bond market gained ground during the reporting period, with the benefit of income augmented by a modest gain in prices. Declining inflation fueled expectations that the U.S. Federal Reserve was set to begin cutting interest rates in 2024, benefiting the broader fixed-income market. Municipal bonds were further helped by positive economic growth, strong issuer fundamentals, and favorable supply-and-demand trends. What contributed to performance? The Fund’s positions in longer-duration and longer-maturity securities were notable contributors. (Duration is a measure of interest rate sensitivity.) The Fund’s holdings in corporate-backed municipals helped results, as did overweights in the utilities and pre-paid gas sectors. The Fund had an above-average weighting in cash, which had no material impact on results due to the attractive yields in this area. The Fund’s use of derivatives marginally contributed to performance. What detracted from performance? At a time of positive returns for the broader asset class, there were few meaningful detractors from Fund performance. With this said, its holdings in high-yield bonds—especially those with deep-discount structures—detracted given that yield spreads remained wide. Bonds issued by Puerto Rico Electric Power Authority were particularly notable detractors in this category due to continued uncertainty in the territory’s financial picture. The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results. |
| Performance Past Does Not Indicate Future [Text] | Past performance is not an indication of future results. |
| Line Graph [Table Text Block] | Fund performance Cumulative performance: June 1, 2014 through May 31, 2024 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance. |
| Average Annual Return [Table Text Block] | Average annual total returns 1 Year 5 Years 10 Years Institutional Shares 4.39 % 1.06 % 2.66 % Bloomberg Municipal Bond Index 2.67 % 0.93 % 2.25 % California Customized Reference Benchmark 3.04 % 0.88 % N/A |
| No Deduction of Taxes [Text Block] | Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. |
| Material Change Date | May 31, 2023 |
| Updated Performance Information Location [Text Block] | Visit blackrock.com |
| Net Assets | $ 2,285,640,268 |
| Holdings Count | Holding | 284 |
| Advisory Fees Paid, Amount | $ 8,253,931 |
| Investment Company Portfolio Turnover | 77% |
| Additional Fund Statistics [Text Block] | Key Fund statistics Net Assets $ % Number of Portfolio Holdings $ % Net Investment Advisory Fees $ % Portfolio Turnover Rate $ % |
| Holdings [Text Block] | What did the Fund invest in? (as of May 31, 2024) Sector allocation Sector (a)(b) Percent of Utilities 30.6 % County/City/Special District/School District 26.4 % Transportation 12.3 % Education 8.1 % Corporate 8.1 % Health 5.9 % State 5.9 % Tobacco 1.8 % Housing 0.9 % Credit quality allocation Credit Rating (a)(c) Percent of AAA/Aaa 18.3 % AA/Aa 52.5 % A 15.8 % BBB/Baa 3.1 % BB/Ba 0.2 % CCC/Caa 0.1 % N/R (d) 10.0 % (a) (b) (c) (d) Excludes short-term securities. (a) (b) (c) (d) For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes. (a) (b) (c) (d) For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. (a) (b) (c) (d) The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Quality Explanation [Text Block] | The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Ratings Selection [Text Block] | For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. |
| Material Fund Change [Text Block] | Material Fund changes This is a summary of certain changes to the Fund since May 31, 2023. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after May 31, 2024 at blackrock.com/fundreports The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Material Fund Change Expenses [Text Block] | The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Updated Prospectus Phone Number | (800) 441-7762 |
| Updated Prospectus Web Address | blackrock.com/fundreports |
| C000038561 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | BlackRock California Municipal Opportunities Fund |
| Class Name | Investor A Shares |
| Trading Symbol | MECMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock California Municipal Opportunities Fund (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 blackrock.com/fundreports . |
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period. |
| Additional Information Phone Number | (800) 441‑7762 |
| Additional Information Website | blackrock.com/fundreports |
| Expenses [Text Block] | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Class name Costs of a $10,000 Costs paid as a percentage of a Investor A Shares $ 0.76 % |
| Expenses Paid, Amount | $ 78 |
| Expense Ratio, Percent | 0.76% |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? The municipal bond market gained ground during the reporting period, with the benefit of income augmented by a modest gain in prices. Declining inflation fueled expectations that the U.S. Federal Reserve was set to begin cutting interest rates in 2024, benefiting the broader fixed-income market. Municipal bonds were further helped by positive economic growth, strong issuer fundamentals, and favorable supply-and-demand trends. What contributed to performance? The Fund’s positions in longer-duration and longer-maturity securities were notable contributors. (Duration is a measure of interest rate sensitivity.) The Fund’s holdings in corporate-backed municipals helped results, as did overweights in the utilities and pre-paid gas sectors. The Fund had an above-average weighting in cash, which had no material impact on results due to the attractive yields in this area. The Fund’s use of derivatives marginally contributed to performance. What detracted from performance? At a time of positive returns for the broader asset class, there were few meaningful detractors from Fund performance. With this said, its holdings in high-yield bonds—especially those with deep-discount structures—detracted given that yield spreads remained wide. Bonds issued by Puerto Rico Electric Power Authority were particularly notable detractors in this category due to continued uncertainty in the territory’s financial picture. The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results. |
| Performance Past Does Not Indicate Future [Text] | Past performance is not an indication of future results. |
| Line Graph [Table Text Block] | Fund performance Cumulative performance: June 1, 2014 through May 31, 2024 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance. |
| Average Annual Return [Table Text Block] | Average annual total returns 1 Year 5 Years 10 Years Investor A Shares 4.13 ) % 0.81 ) % 2.42 % Investor A Shares (with sales charge) (0.29 ) % (0.06 ) % 1.98 % Bloomberg Municipal Bond Index 2.67 ) % 0.93 ) % 2.25 % California Customized Reference Benchmark 3.04 ) % 0.88 ) % N/A |
| No Deduction of Taxes [Text Block] | Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. |
| Material Change Date | May 31, 2023 |
| Updated Performance Information Location [Text Block] | Visit blackrock.com |
| Net Assets | $ 2,285,640,268 |
| Holdings Count | Holding | 284 |
| Advisory Fees Paid, Amount | $ 8,253,931 |
| Investment Company Portfolio Turnover | 77% |
| Additional Fund Statistics [Text Block] | Key Fund statistics Net Assets $ % Number of Portfolio Holdings $ % Net Investment Advisory Fees $ % Portfolio Turnover Rate $ % |
| Holdings [Text Block] | What did the Fund invest in? (as of May 31, 2024) Sector allocation Sector (a)(b) Percent of Utilities 30.6 % County/City/Special District/School District 26.4 % Transportation 12.3 % Education 8.1 % Corporate 8.1 % Health 5.9 % State 5.9 % Tobacco 1.8 % Housing 0.9 % Credit quality allocation Credit Rating (a)(c) Percent of AAA/Aaa 18.3 % AA/Aa 52.5 % A 15.8 % BBB/Baa 3.1 % BB/Ba 0.2 % CCC/Caa 0.1 % N/R (d) 10.0 % (a) (b) (c) (d) Excludes short-term securities. (a) (b) (c) (d) For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes. (a) (b) (c) (d) For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. (a) (b) (c) (d) The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Quality Explanation [Text Block] | The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Ratings Selection [Text Block] | For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. |
| Material Fund Change [Text Block] | Material Fund changes This is a summary of certain changes to the Fund since May 31, 2023. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after May 31, 2024 at blackrock.com/fundreports The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Material Fund Change Expenses [Text Block] | The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Updated Prospectus Phone Number | (800) 441-7762 |
| Updated Prospectus Web Address | blackrock.com/fundreports |
| C000038562 [Member] | |
| Shareholder Report [Line Items] | |
| Fund Name | BlackRock California Municipal Opportunities Fund |
| Class Name | Investor C Shares |
| Trading Symbol | MFCMX |
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about BlackRock California Municipal Opportunities Fund (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 blackrock.com/fundreports . |
| Material Fund Change Notice [Text Block] | This report describes changes to the Fund that occurred during the reporting period. |
| Additional Information Phone Number | (800) 441‑7762 |
| Additional Information Website | blackrock.com/fundreports |
| Expenses [Text Block] | What were the Fund costs for the last year? (based on a hypothetical $10,000 investment) Class name Costs of a $10,000 Costs paid as a percentage of a Investor C Shares $ 1.52 % |
| Expenses Paid, Amount | $ 155 |
| Expense Ratio, Percent | 1.52% |
| Factors Affecting Performance [Text Block] | How did the Fund perform last year? The municipal bond market gained ground during the reporting period, with the benefit of income augmented by a modest gain in prices. Declining inflation fueled expectations that the U.S. Federal Reserve was set to begin cutting interest rates in 2024, benefiting the broader fixed-income market. Municipal bonds were further helped by positive economic growth, strong issuer fundamentals, and favorable supply-and-demand trends. What contributed to performance? The Fund’s positions in longer-duration and longer-maturity securities were notable contributors. (Duration is a measure of interest rate sensitivity.) The Fund’s holdings in corporate-backed municipals helped results, as did overweights in the utilities and pre-paid gas sectors. The Fund had an above-average weighting in cash, which had no material impact on results due to the attractive yields in this area. The Fund’s use of derivatives marginally contributed to performance. What detracted from performance? At a time of positive returns for the broader asset class, there were few meaningful detractors from Fund performance. With this said, its holdings in high-yield bonds—especially those with deep-discount structures—detracted given that yield spreads remained wide. Bonds issued by Puerto Rico Electric Power Authority were particularly notable detractors in this category due to continued uncertainty in the territory’s financial picture. The views expressed reflect the opinions of BlackRock as of the date of this report and are subject to change based on changes in market, economic or other conditions. These views are not intended to be a forecast of future events and are no guarantee of future results. |
| Performance Past Does Not Indicate Future [Text] | Past performance is not an indication of future results. |
| Line Graph [Table Text Block] | Fund performance Cumulative performance: June 1, 2014 through May 31, 2024 Initial investment of $10,000 See “Average annual total returns” for additional information on fund performance. |
| Average Annual Return [Table Text Block] | Average annual total returns 1 Year 5 Years 10 Years Investor C Shares 3.35 % 0.05 % 1.79 % Investor C Shares (with sales charge) 2.35 % 0.05 % 1.79 % Bloomberg Municipal Bond Index 2.67 % 0.93 % 2.25 % California Customized Reference Benchmark 3.04 % 0.88 % N/A |
| No Deduction of Taxes [Text Block] | Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares. |
| Material Change Date | May 31, 2023 |
| Updated Performance Information Location [Text Block] | Visit blackrock.com |
| Net Assets | $ 2,285,640,268 |
| Holdings Count | Holding | 284 |
| Advisory Fees Paid, Amount | $ 8,253,931 |
| Investment Company Portfolio Turnover | 77% |
| Additional Fund Statistics [Text Block] | Key Fund statistics Net Assets $ % Number of Portfolio Holdings $ % Net Investment Advisory Fees $ % Portfolio Turnover Rate $ % |
| Holdings [Text Block] | What did the Fund invest in? (as of May 31, 2024) Sector allocation Sector (a)(b) Percent of Utilities 30.6 % County/City/Special District/School District 26.4 % Transportation 12.3 % Education 8.1 % Corporate 8.1 % Health 5.9 % State 5.9 % Tobacco 1.8 % Housing 0.9 % Credit quality allocation Credit Rating (a)(c) Percent of AAA/Aaa 18.3 % AA/Aa 52.5 % A 15.8 % BBB/Baa 3.1 % BB/Ba 0.2 % CCC/Caa 0.1 % N/R (d) 10.0 % (a) (b) (c) (d) Excludes short-term securities. (a) (b) (c) (d) For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes. (a) (b) (c) (d) For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. (a) (b) (c) (d) The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Quality Explanation [Text Block] | The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments. |
| Credit Ratings Selection [Text Block] | For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. |
| Material Fund Change [Text Block] | Material Fund changes This is a summary of certain changes to the Fund since May 31, 2023. For more complete information, you may review the Fund’s next prospectus, which we expect to be available approximately 120 days after May 31, 2024 at blackrock.com/fundreports The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Material Fund Change Expenses [Text Block] | The net expense ratio decreased from the prior fiscal year end primarily due to a decrease in expenses related to financing activities. |
| Updated Prospectus Phone Number | (800) 441-7762 |
| Updated Prospectus Web Address | blackrock.com/fundreports |
| Shareholder Report, Line Graph (Details) - USD ($) | 12 Months Ended | 60 Months Ended | 120 Months Ended | |||||||||
| May 31, 2024 | May 31, 2024 | May 31, 2024 | May 31, 2023 | May 31, 2022 | May 31, 2021 | May 31, 2020 | May 31, 2019 | May 31, 2018 | May 31, 2017 | May 31, 2016 | May 31, 2015 | |
| C000011299 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Investor A1 Shares | |||||||||||
| Account Value | $ 12,876 | $ 12,876 | $ 12,876 | $ 12,346 | $ 12,329 | $ 13,137 | $ 12,025 | $ 12,271 | $ 11,778 | $ 11,287 | $ 11,090 | $ 10,428 |
| Average Annual Return, Percent | 4.29% | 0.97% | 2.56% | |||||||||
| C000199773 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Class K Shares | |||||||||||
| Account Value | $ 13,047 | $ 13,047 | $ 13,047 | 12,493 | 12,458 | 13,255 | 12,126 | 12,358 | 11,836 | 11,338 | 11,129 | 10,446 |
| Average Annual Return, Percent | 4.44% | 1.09% | 2.70% | |||||||||
| C000011302 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Institutional Shares | |||||||||||
| Account Value | $ 13,006 | $ 13,006 | $ 13,006 | 12,460 | 12,431 | 13,234 | 12,112 | 12,340 | 11,834 | 11,338 | 11,129 | 10,446 |
| Average Annual Return, Percent | 4.39% | 1.06% | 2.66% | |||||||||
| C000038561 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Investor A Shares (with sales charge) | |||||||||||
| Account Value | $ 12,160 | $ 12,160 | $ 12,160 | 11,677 | 11,679 | 12,464 | 11,425 | 11,679 | 11,228 | 10,776 | 10,604 | 9,982 |
| Average Annual Return, Percent | (0.29%) | (0.06%) | 1.98% | |||||||||
| C000038561 [Member] | Without Sales Load [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Investor A Shares | |||||||||||
| Average Annual Return, Percent | 4.13% | 0.81% | 2.42% | |||||||||
| C000038562 [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Investor C Shares (with sales charge) | |||||||||||
| Account Value | $ 11,947 | $ 11,947 | $ 11,947 | 11,472 | 11,474 | 12,338 | 11,405 | 11,737 | 11,368 | 11,002 | 10,907 | 10,338 |
| Average Annual Return, Percent | 2.35% | 0.05% | 1.79% | |||||||||
| C000038562 [Member] | Without Sales Load [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Investor C Shares | |||||||||||
| Average Annual Return, Percent | 3.35% | 0.05% | 1.79% | |||||||||
| Bloomberg Municipal Bond Index [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | |||||||||||
| Account Value | $ 12,488 | $ 12,488 | $ 12,488 | $ 12,163 | $ 12,104 | $ 12,986 | $ 12,399 | $ 11,925 | $ 11,207 | $ 11,083 | $ 10,924 | $ 10,318 |
| Average Annual Return, Percent | 2.67% | 0.93% | 2.25% | |||||||||
| California Customized Reference Benchmark [Member] | ||||||||||||
| Account Value [Line Items] | ||||||||||||
| Line Graph and Table Measure Name | California Customized Reference Benchmark | |||||||||||
| Average Annual Return, Percent | 3.04% | 0.88% |
| Shareholder Report, Holdings (Details) | May 31, 2024 | |
| C000011299 [Member] | N R [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 10% | [1],[2],[3] |
| C000011299 [Member] | Corporate sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [1],[4] |
| C000011299 [Member] | Utilities Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 30.60% | [1],[4] |
| C000011299 [Member] | Transportation Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 12.30% | [1],[4] |
| C000011299 [Member] | State [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [1],[4] |
| C000011299 [Member] | County City Special District School District [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 26.40% | [1],[4] |
| C000011299 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [1],[4] |
| C000011299 [Member] | Education [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [1],[4] |
| C000011299 [Member] | Housing [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 0.90% | [1],[4] |
| C000011299 [Member] | Tobacco [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 1.80% | [1],[4] |
| C000199773 [Member] | N R [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 10% | [5],[6],[7] |
| C000199773 [Member] | Corporate sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [5],[8] |
| C000199773 [Member] | Utilities Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 30.60% | [5],[8] |
| C000199773 [Member] | Transportation Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 12.30% | [5],[8] |
| C000199773 [Member] | State [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [5],[8] |
| C000199773 [Member] | County City Special District School District [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 26.40% | [5],[8] |
| C000199773 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [5],[8] |
| C000199773 [Member] | Education [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [5],[8] |
| C000199773 [Member] | Housing [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 0.90% | [5],[8] |
| C000199773 [Member] | Tobacco [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 1.80% | [5],[8] |
| C000011302 [Member] | N R [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 10% | [9],[10],[11] |
| C000011302 [Member] | Corporate sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [9],[12] |
| C000011302 [Member] | Utilities Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 30.60% | [9],[12] |
| C000011302 [Member] | Transportation Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 12.30% | [9],[12] |
| C000011302 [Member] | State [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [9],[12] |
| C000011302 [Member] | County City Special District School District [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 26.40% | [9],[12] |
| C000011302 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [9],[12] |
| C000011302 [Member] | Education [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [9],[12] |
| C000011302 [Member] | Housing [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 0.90% | [9],[12] |
| C000011302 [Member] | Tobacco [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 1.80% | [9],[12] |
| C000038561 [Member] | N R [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 10% | [13],[14],[15] |
| C000038561 [Member] | Corporate sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [13],[16] |
| C000038561 [Member] | Utilities Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 30.60% | [13],[16] |
| C000038561 [Member] | Transportation Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 12.30% | [13],[16] |
| C000038561 [Member] | State [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [13],[16] |
| C000038561 [Member] | County City Special District School District [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 26.40% | [13],[16] |
| C000038561 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [13],[16] |
| C000038561 [Member] | Education [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [13],[16] |
| C000038561 [Member] | Housing [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 0.90% | [13],[16] |
| C000038561 [Member] | Tobacco [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 1.80% | [13],[16] |
| C000038562 [Member] | N R [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 10% | [17],[18],[19] |
| C000038562 [Member] | Corporate sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [17],[20] |
| C000038562 [Member] | Utilities Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 30.60% | [17],[20] |
| C000038562 [Member] | Transportation Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 12.30% | [17],[20] |
| C000038562 [Member] | State [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [17],[20] |
| C000038562 [Member] | County City Special District School District [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 26.40% | [17],[20] |
| C000038562 [Member] | Healthcare Sector [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 5.90% | [17],[20] |
| C000038562 [Member] | Education [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 8.10% | [17],[20] |
| C000038562 [Member] | Housing [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 0.90% | [17],[20] |
| C000038562 [Member] | Tobacco [Member] | ||
| Holdings [Line Items] | ||
| Percent of Total Investments | 1.80% | [17],[20] |
| [1]Excludes short-term securities.[2]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.[3]The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments.[4]For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes.[5]Excludes short-term securities.[6]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.[7]The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments.[8]For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes.[9]Excludes short-term securities.[10]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.[11]The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments.[12]For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes.[13]Excludes short-term securities.[14]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.[15]The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments.[16]For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes.[17]Excludes short-term securities.[18]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.[19]The investment adviser evaluates the credit quality of unrated investments based upon certain factors including, but not limited to, credit ratings for similar investments and financial analysis of sectors and individual investments. Using this approach, the investment adviser has deemed certain of these unrated securities as investment grade quality. As of May 31, 2024, the market value of unrated securities deemed by the investment adviser to be investment grade represents less than 1.0% of total investments.[20]For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes. | ||
| Label | Element | Value | |
| C000038562 [Member] | Standard & Poor's, BB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.20% | [1],[2] |
| C000038562 [Member] | Standard & Poor's, BBB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 3.10% | [1],[2] |
| C000038562 [Member] | Standard & Poor's, CCC Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.10% | [1],[2] |
| C000038562 [Member] | Standard & Poor's, AAA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 18.30% | [1],[2] |
| C000038562 [Member] | Standard & Poor's, AA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 52.50% | [1],[2] |
| C000038562 [Member] | Standard & Poor's, A Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 15.80% | [1],[2] |
| C000011299 [Member] | Standard & Poor's, BB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.20% | [3],[4] |
| C000011299 [Member] | Standard & Poor's, BBB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 3.10% | [3],[4] |
| C000011299 [Member] | Standard & Poor's, CCC Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.10% | [3],[4] |
| C000011299 [Member] | Standard & Poor's, AAA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 18.30% | [3],[4] |
| C000011299 [Member] | Standard & Poor's, AA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 52.50% | [3],[4] |
| C000011299 [Member] | Standard & Poor's, A Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 15.80% | [3],[4] |
| C000199773 [Member] | Standard & Poor's, BB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.20% | [5],[6] |
| C000199773 [Member] | Standard & Poor's, BBB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 3.10% | [5],[6] |
| C000199773 [Member] | Standard & Poor's, CCC Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.10% | [5],[6] |
| C000199773 [Member] | Standard & Poor's, AAA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 18.30% | [5],[6] |
| C000199773 [Member] | Standard & Poor's, AA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 52.50% | [5],[6] |
| C000199773 [Member] | Standard & Poor's, A Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 15.80% | [5],[6] |
| C000038561 [Member] | Standard & Poor's, BB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.20% | [7],[8] |
| C000038561 [Member] | Standard & Poor's, BBB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 3.10% | [7],[8] |
| C000038561 [Member] | Standard & Poor's, CCC Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.10% | [7],[8] |
| C000038561 [Member] | Standard & Poor's, AAA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 18.30% | [7],[8] |
| C000038561 [Member] | Standard & Poor's, AA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 52.50% | [7],[8] |
| C000038561 [Member] | Standard & Poor's, A Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 15.80% | [7],[8] |
| C000011302 [Member] | Standard & Poor's, BB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.20% | [9],[10] |
| C000011302 [Member] | Standard & Poor's, BBB Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 3.10% | [9],[10] |
| C000011302 [Member] | Standard & Poor's, CCC Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 0.10% | [9],[10] |
| C000011302 [Member] | Standard & Poor's, AAA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 18.30% | [9],[10] |
| C000011302 [Member] | Standard & Poor's, AA Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 52.50% | [9],[10] |
| C000011302 [Member] | Standard & Poor's, A Rating [Member] | |||
| Percent of Total Investments | oef_PctOfTotalInv | 15.80% | [9],[10] |
| [1]Excludes short-term securities.[2]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.[3]Excludes short-term securities.[4]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.[5]Excludes short-term securities.[6]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.[7]Excludes short-term securities.[8]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.[9]Excludes short-term securities.[10]For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change. | |||
