v3.26.1
Shareholder Report, Average Annual Return (Details)
12 Months Ended 60 Months Ended 65 Months Ended 110 Months Ended 120 Months Ended
Apr. 30, 2026
Apr. 30, 2026
Apr. 30, 2026
Apr. 30, 2026
Apr. 30, 2026
C000101627          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000112445          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000112461          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000176891          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000053010          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000088892          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000053007          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000053008          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000221911          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000221910          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000119796          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
C000053009          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name Fund        
Without Sales Load [Member] | C000101627          
Average Annual Return [Line Items]          
Average Annual Return, Percent 10.07% (0.90%)     2.02%
Without Sales Load [Member] | C000112445          
Average Annual Return [Line Items]          
Average Annual Return, Percent 10.64% 3.11%     4.68%
Without Sales Load [Member] | C000112461          
Average Annual Return [Line Items]          
Average Annual Return, Percent 10.00% 3.53%     6.33%
Without Sales Load [Member] | C000176891          
Average Annual Return [Line Items]          
Average Annual Return, Percent 4.74% 0.87%   2.26%  
Without Sales Load [Member] | C000053010          
Average Annual Return [Line Items]          
Average Annual Return, Percent 5.92% (0.05%)     1.99%
Without Sales Load [Member] | C000088892          
Average Annual Return [Line Items]          
Average Annual Return, Percent 5.54% 4.41%     3.44%
Without Sales Load [Member] | C000053007          
Average Annual Return [Line Items]          
Average Annual Return, Percent 6.56% 0.45%     1.91%
Without Sales Load [Member] | C000053008          
Average Annual Return [Line Items]          
Average Annual Return, Percent 6.37% (0.93%)     1.59%
Without Sales Load [Member] | C000221911          
Average Annual Return [Line Items]          
Average Annual Return, Percent 5.11% 1.23% 1.08%    
Without Sales Load [Member] | C000221910          
Average Annual Return [Line Items]          
Average Annual Return, Percent 4.83% 1.10% 0.84%    
Without Sales Load [Member] | C000119796          
Average Annual Return [Line Items]          
Average Annual Return, Percent 5.29% 1.02%     2.03%
Without Sales Load [Member] | C000053009          
Average Annual Return [Line Items]          
Average Annual Return, Percent 4.06% 1.14%     1.47%
ICE US Broad Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE US Broad Municipal Index        
Average Annual Return, Percent 5.95% 1.00%     2.19%
ICE BofA Global Broad Market Plus Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE BofA Global Broad Market Plus Index        
Average Annual Return, Percent 2.27% (1.67%)     0.42%
ICE BofA US Broad Market Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE BofA US Broad Market Index        
Average Annual Return, Percent 4.08% 0.18%     1.68%
ICE BofA US Broad Market Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE BofA US Broad Market Index        
Average Annual Return, Percent 4.08% 0.18%   1.90%  
ICE US Broad Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE US Broad Municipal Index        
Average Annual Return, Percent 5.95% 1.00%     2.19%
ICE BofA US Broad Market Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE BofA US Broad Market Index        
Average Annual Return, Percent 4.08% 0.18%     1.68%
ICE US Broad Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE US Broad Municipal Index        
Average Annual Return, Percent 5.95% 1.00%     2.19%
ICE US Broad Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE US Broad Municipal Index        
Average Annual Return, Percent 5.95% 1.00%     2.19%
ICE BofA US Broad Market Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE BofA US Broad Market Index        
Average Annual Return, Percent 4.08% 0.18% (0.25%)    
ICE BofA US Broad Market Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE BofA US Broad Market Index        
Average Annual Return, Percent 4.08% 0.18% (0.25%)    
ICE US Broad Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE US Broad Municipal Index        
Average Annual Return, Percent 5.95% 1.00%     2.19%
ICE US Broad Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE US Broad Municipal Index        
Average Annual Return, Percent 5.95% 1.00%     2.19%
S-Network Municipal Bond Closed-End Fund Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name S-Network Municipal Bond Closed-End Fund Index        
Average Annual Return, Percent 10.47% (0.51%)     2.39%
ICE BofA Diversified High Yield US Emerging Markets Corp Plus Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE BofA Diversified High Yield US Emerging Markets Corp Plus Index        
Average Annual Return, Percent 10.95% 3.02%     4.87%
ICE US Fallen Angel High Yield 10% Constrained Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE US Fallen Angel High Yield 10% Constrained Index        
Average Annual Return, Percent 9.97% 3.71%     6.73%
S&P Green Bond U.S. Dollar Select Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name S&P Green Bond U.S. Dollar Select Index        
Average Annual Return, Percent 4.88% 1.02%   2.62%  
ICE Broad High Yield Crossover Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE Broad High Yield Crossover Municipal Index        
Average Annual Return, Percent 6.15% 1.72%     3.89%
MVIS® US Investment Grade Floating Rate Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name MVIS<sup style="inset: 1.5px 0px 4px; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 700; grid-area: auto; line-height: 0px; margin: 0px; overflow: visible; position: relative; text-align: center; text-align-last: auto; white-space-collapse: preserve-breaks;">®</sup> US Investment Grade Floating Rate Index        
Average Annual Return, Percent 5.64% 4.42%     3.60%
ICE Intermediate AMT-Free Broad National Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE Intermediate AMT-Free Broad National Municipal Index        
Average Annual Return, Percent 6.69% 0.70%     2.30%
ICE Long AMT-Free Broad National Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE Long AMT-Free Broad National Municipal Index        
Average Annual Return, Percent 6.58% (0.26%)     2.25%
MVIS® Moody's Analytics US BBB Corporate Bond Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name MVIS<sup style="inset: 1.5px 0px 4px; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 700; grid-area: auto; line-height: 0px; margin: 0px; overflow: visible; position: relative; text-align: center; text-align-last: auto; white-space-collapse: preserve-breaks;">®</sup> Moody's Analytics US BBB Corporate Bond Index        
Average Annual Return, Percent 5.44% 1.36% 1.19%    
MVIS® Moody's Analytics US Investment Grade Corporate Bond Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name MVIS<sup style="inset: 1.5px 0px 4px; box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 12px; font-weight: 700; grid-area: auto; line-height: 0px; margin: 0px; overflow: visible; position: relative; text-align: center; text-align-last: auto; white-space-collapse: preserve-breaks;">®</sup> Moody's Analytics US Investment Grade Corporate Bond Index        
Average Annual Return, Percent 5.03% 1.19% 0.89%    
ICE 1-12 Year Broad High Yield Crossover Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE 1-12 Year Broad High Yield Crossover Municipal Index        
Average Annual Return, Percent 4.98% 2.42%     3.34%
ICE Short AMT-Free Broad National Municipal Index          
Average Annual Return [Line Items]          
Line Graph and Table Measure Name ICE Short AMT-Free Broad National Municipal Index        
Average Annual Return, Percent 4.02% 1.16%     1.67%