S000003888 [Member] Annual Fund Operating Expenses - Putnam VT Small Cap Value Fund |
Dec. 31, 2025 |
|---|---|
| Class IA Shares | |
| Prospectus [Line Items] | |
| Management Fees (as a percentage of Assets) | 0.60% |
| Distribution and Service (12b-1) Fees | 0.00% |
| Other Expenses (as a percentage of Assets): | 0.17% |
| Expenses (as a percentage of Assets) | 0.77% |
| Class IB Shares | |
| Prospectus [Line Items] | |
| Management Fees (as a percentage of Assets) | 0.60% |
| Distribution and Service (12b-1) Fees | 0.25% |
| Other Expenses (as a percentage of Assets): | 0.17% |
| Expenses (as a percentage of Assets) | 1.02% |