Shareholder Report, Line Graph (Details) |
6 Months Ended |
|---|---|
Jun. 30, 2026 | |
| C000009551 [Member] | |
| Account Value [Line Items] | |
| Line Graph and Table Measure Name | Selected American Shares (Class S) |
| C000009552 [Member] | |
| Account Value [Line Items] | |
| Line Graph and Table Measure Name | Selected American Shares (Class D) |
| Standard & Poor's 500 Index [Member] | |
| Account Value [Line Items] | |
| Line Graph and Table Measure Name | S&P 500 Index |
| Russell 1000 Value Index [Member] | |
| Account Value [Line Items] | |
| Line Graph and Table Measure Name | Russell 1000 Value Index |