Mid-Cap Index Portfolio Annual Fund Operating Expenses - Portfolio [Member] - Mid-Cap Index Portfolio - Mid-Cap Index Portfolio |
Dec. 31, 2025 |
|---|---|
| Prospectus [Line Items] | |
| Management Fees (as a percentage of Assets) | 0.16% |
| Distribution and Service (12b-1) Fees | 0.00% |
| Other Expenses (as a percentage of Assets): | 0.01% |
| Expenses (as a percentage of Assets) | 0.17% |