v3.25.1
Shareholder Report, Holdings (Details)
Mar. 31, 2025
C000003891 [Member] | N R [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.20% [1],[2]
C000003891 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.40% [1],[2]
C000003891 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.00% [1],[2],[3]
C000003891 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.10% [1],[2]
C000003891 [Member] | Standard & Poor's, BB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.30% [1],[2]
C000003891 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 27.00% [1],[2]
C000003891 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 88.90% [1]
C000003891 [Member] | Municipal Bonds [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.90% [1]
C000003891 [Member] | U S Treasury Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.00% [1]
C000003891 [Member] | Foreign Government Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.00% [1]
C000003891 [Member] | Foreign Agency Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.90% [1]
C000003891 [Member] | Preferred Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.30% [1]
C000003892 [Member] | N R [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.20% [4],[5]
C000003892 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20% [4],[5]
C000003892 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 97.30% [4],[5],[6]
C000003892 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10% [4],[5]
C000003892 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.20% [4],[5]
C000003892 [Member] | U S Government Sponsored Agency Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 93.10% [4]
C000003892 [Member] | Non Agency Mortgage Backed Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.40% [4]
C000003892 [Member] | Asset-Backed Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [4]
C000003893 [Member] | N R [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [7]
C000003893 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.70% [7]
C000003893 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 61.40% [7],[8]
C000003893 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.00% [7]
C000003893 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.90% [7]
C000003893 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 33.50% [9]
C000003893 [Member] | U S Treasury Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.90% [9]
C000003893 [Member] | Foreign Government Obligations [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40% [9]
C000003893 [Member] | U S Government Sponsored Agency Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.00% [9]
C000003893 [Member] | Non Agency Mortgage Backed Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.20% [9]
C000003893 [Member] | Asset-Backed Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 24.00% [9]
C000032703 [Member] | Fixed Income Funds [Member]  
Holdings [Line Items]  
Percent of Total Investments 21.00%
C000032703 [Member] | Short-Term Investments [Member]  
Holdings [Line Items]  
Percent of Total Investments 79.00%
C000144517 [Member] | N R [Member]  
Holdings [Line Items]  
Percent of Total Investments 48.50% [10]
C000144517 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.70% [10]
C000144517 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.80% [10]
C000144517 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.50% [10]
C000144517 [Member] | Standard & Poor's, BB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.90% [10]
C000144517 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.80% [10]
C000144517 [Member] | Standard & Poor's, B Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.50% [10]
C000144517 [Member] | Standard & Poor's, CCC Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30% [10]
C000144517 [Member] | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Total Investments 11.30%
C000144517 [Member] | Transportation Sector [Member]  
Holdings [Line Items]  
Percent of Total Investments 17.00%
C000144517 [Member] | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.70%
C000144517 [Member] | County City Special District School District [Member]  
Holdings [Line Items]  
Percent of Total Investments 35.90%
C000144517 [Member] | Education [Member]  
Holdings [Line Items]  
Percent of Total Investments 10.60%
C000144517 [Member] | Housing [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.90%
C000144517 [Member] | Tobacco [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.60%
C000146955 [Member] | N R [Member]  
Holdings [Line Items]  
Percent of Total Investments 44.50% [11],[12]
C000146955 [Member] | Standard & Poor's, AA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.20% [11],[12]
C000146955 [Member] | Standard & Poor's, AAA Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 36.50% [11],[12],[13]
C000146955 [Member] | Standard & Poor's, BBB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.90% [11],[12]
C000146955 [Member] | Standard & Poor's, BB Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 3.40% [11],[12]
C000146955 [Member] | Standard & Poor's, A Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 2.80% [11],[12]
C000146955 [Member] | Standard & Poor's, B Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80% [11],[12]
C000146955 [Member] | Standard & Poor's, CCC Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.70% [11],[12]
C000146955 [Member] | Standard & Poor's, CC Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.20% [11],[12]
C000146955 [Member] | Standard & Poor's, C Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.90% [11],[12]
C000146955 [Member] | Standard & Poor's, D Rating [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.10% [11],[12]
C000146955 [Member] | Corporate Bond Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments [11],[14]
C000146955 [Member] | U S Government Sponsored Agency Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.40% [11]
C000146955 [Member] | Non Agency Mortgage Backed Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 50.00% [11]
C000146955 [Member] | Asset-Backed Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 49.30% [11]
C000146955 [Member] | Floating Rate Loan Interests [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.30% [11]
C000227189 [Member] | Healthcare Sector [Member]  
Holdings [Line Items]  
Percent of Total Investments 19.30%
C000227189 [Member] | Transportation Sector [Member]  
Holdings [Line Items]  
Percent of Total Investments 0.80%
C000227189 [Member] | Utilities Sector [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.50%
C000227189 [Member] | County City Special District School District [Member]  
Holdings [Line Items]  
Percent of Total Investments 25.10%
C000227189 [Member] | Education [Member]  
Holdings [Line Items]  
Percent of Total Investments 15.80%
C000227189 [Member] | Housing [Member]  
Holdings [Line Items]  
Percent of Total Investments 26.50%
[1] Excludes short-term securities, short investments and options, if any.
[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, individual investments and/or issuers. Using this approach, the investment adviser has deemed unrated U.S. Government Sponsored Agency Securities and U.S. Treasury Obligations to be of similar credit quality as investments rated AAA/Aaa.
[4] Excludes short-term securities, short investments and options, if any.
[5] 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.
[6] 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, individual investments and/or issuers. Using this approach, the investment adviser has deemed unrated U.S. Government Sponsored Agency Securities and U.S. Treasury Obligations to be of similar credit quality as investments rated AAA/Aaa.
[7] 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.
[8] 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, individual investments and/or issuers. Using this approach, the investment adviser has deemed unrated U.S. Government Sponsored Agency Securities and U.S. Treasury Obligations to be of similar credit quality as investments rated AAA/Aaa.
[9] Excludes short-term securities, short investments and options, if any.
[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] Excludes short-term securities, short investments and options, if any.
[12] 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.
[13] 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, individual investments and/or issuers. Using this approach, the investment adviser has deemed unrated U.S. Government Sponsored Agency Securities and U.S. Treasury Obligations to be of similar credit quality as investments rated AAA/Aaa.
[14] Rounds to less than 0.1%.