v3.26.1
Shareholder Report, Average Annual Return (Details)
 12 Months Ended 60 Months Ended 75 Months Ended 120 Months Ended
May 31, 2026
May 31, 2026
May 31, 2026
May 31, 2026
Without Sales Load [Member] | C000005524        
Average Annual Return [Line Items]        
Average Annual Return, Percent 7.43% 4.16%   5.35%
Without Sales Load [Member] | C000005525        
Average Annual Return [Line Items]        
Average Annual Return, Percent 7.09% 3.80%   5.05%
Without Sales Load [Member] | C000159675        
Average Annual Return [Line Items]        
Average Annual Return, Percent 7.51% 4.22%   5.46%
Without Sales Load [Member] | C000219342        
Average Annual Return [Line Items]        
Average Annual Return, Percent 8.18% 4.86% 7.59%  
Bloomberg U.S. Aggregate Bond Index        
Average Annual Return [Line Items]        
Average Annual Return, Percent 5.13% 0.17%   1.70%
Bloomberg U.S. Aggregate Bond Index        
Average Annual Return [Line Items]        
Average Annual Return, Percent 5.13% 0.17%   1.70%
Bloomberg U.S. Aggregate Bond Index        
Average Annual Return [Line Items]        
Average Annual Return, Percent 5.13% 0.17%   1.70%
Bloomberg U.S. Aggregate Bond Index        
Average Annual Return [Line Items]        
Average Annual Return, Percent 5.13% 0.17% 0.42%  
Bloomberg U.S. High-Yield 2% Issuer Capped Bond Index        
Average Annual Return [Line Items]        
Average Annual Return, Percent 7.57% 4.39%   5.87%
Bloomberg U.S. High-Yield 2% Issuer Capped Bond Index        
Average Annual Return [Line Items]        
Average Annual Return, Percent 7.57% 4.39%   5.87%
Bloomberg U.S. High-Yield 2% Issuer Capped Bond Index        
Average Annual Return [Line Items]        
Average Annual Return, Percent 7.57% 4.39%   5.87%
Bloomberg U.S. High-Yield 2% Issuer Capped Bond Index        
Average Annual Return [Line Items]        
Average Annual Return, Percent 7.57% 4.39% 7.14%