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] | C000005534 | |||
| Average Annual Return [Line Items] | |||
| Average Annual Return, Percent | 14.50% | 4.83% | 6.80% |
| Without Sales Load [Member] | C000169940 | |||
| Average Annual Return [Line Items] | |||
| Average Annual Return, Percent | 14.70% | 4.97% | 6.91% |
| 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% |
| Morningstar Moderately Conservative Target Risk Index | |||
| Average Annual Return [Line Items] | |||
| Average Annual Return, Percent | 13.62% | 4.36% | 6.24% |
| Morningstar Moderately Conservative Target Risk Index | |||
| Average Annual Return [Line Items] | |||
| Average Annual Return, Percent | 13.62% | 4.36% | 6.24% |