Shareholder Report, Holdings (Details) - C000009559 [Member] |
Jun. 30, 2026 |
|---|---|
| Health Care REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 10.04% |
| Industrial REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.23% |
| Residential REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 16.60% |
| Office REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 19.96% |
| Specialized REITs [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 23.65% |