v3.26.1
S000003879 [Member] Average Annual Total Returns
 12 Months Ended 60 Months Ended 120 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
MSCI All Country World Ex-U.S. Index-NR (reflects no deduction for fees, expenses or taxes but are net of dividend tax withholdings)      
Prospectus [Line Items]      
Average Annual Return, Percent [1] 32.39% 7.91% 8.41%
MSCI Emerging Markets Index-NR (index reflects no deduction for fees, expenses or taxes but are net of dividend tax withholding)      
Prospectus [Line Items]      
Average Annual Return, Percent 33.57% 4.20% 8.42%
Putnam VT Emerging Markets Equity Linked Benchmark (no deduction for fees, expenses or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 33.57% 4.20% 8.01%
Class IA Shares      
Prospectus [Line Items]      
Average Annual Return, Percent 34.49% 4.02% 7.29%
Class IB Shares      
Prospectus [Line Items]      
Average Annual Return, Percent 34.16% 3.75% 7.01%
[1]
Effective May 1, 2026, the fund will no longer compare its performance to the MSCI All Country World Ex-U.S. Index-NR.