S000003888 [Member] Annual Total Returns |
12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Putnam VT Small Cap Value Fund | Class IA Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 5.46% | 6.48% | 24.13% | (12.80%) | 40.37% | 4.12% | 24.12% | (19.42%) | 8.15% | 27.70% |