S000003887 [Member] Expense Example, No Redemption - Putnam VT Research Fund |
Dec. 31, 2025
USD ($)
|
|---|---|
| Class IA Shares | |
| Prospectus [Line Items] | |
| Expense Example, No Redemption, 1 Year | $ 69 |
| Expense Example, No Redemption, 3 Years | 217 |
| Expense Example, No Redemption, 5 Years | 378 |
| Expense Example, No Redemption, 10 Years | 846 |
| Class IB Shares | |
| Prospectus [Line Items] | |
| Expense Example, No Redemption, 1 Year | 95 |
| Expense Example, No Redemption, 3 Years | 297 |
| Expense Example, No Redemption, 5 Years | 515 |
| Expense Example, No Redemption, 10 Years | $ 1,144 |