v3.26.1
Shareholder Report, Average Annual Return (Details)
 12 Months Ended 60 Months Ended 120 Months Ended
May 31, 2026
May 31, 2026
May 31, 2026
Without Sales Load [Member] | C000129654      
Average Annual Return [Line Items]      
Average Annual Return, Percent 11.76% 4.14% 5.93%
Without Sales Load [Member] | C000129655      
Average Annual Return [Line Items]      
Average Annual Return, Percent 11.58% 3.90% 5.67%
Without Sales Load [Member] | C000169038      
Average Annual Return [Line Items]      
Average Annual Return, Percent 11.92% 4.30% 6.07%
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%
S&P Target Date Retirement Income Index      
Average Annual Return [Line Items]      
Average Annual Return, Percent 12.59% 4.59% 5.47%
S&P Target Date Retirement Income Index      
Average Annual Return [Line Items]      
Average Annual Return, Percent 12.59% 4.59% 5.47%
S&P Target Date Retirement Income Index      
Average Annual Return [Line Items]      
Average Annual Return, Percent 12.59% 4.59% 5.47%