S000003883 [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 Growth Fund | Class IA Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 9.07% | 23.67% | 23.46% | (28.11%) | 14.18% | 48.71% | 37.73% | (13.64%) | 8.26% | 15.77% |