v3.26.3
Stock-Based Compensation - Non-Plan Co-Founder and Head of Blend Options (Details) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 9 Months Ended
Mar. 31, 2021
Sep. 30, 2026
Mar. 31, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock based compensation expense   $ 6,033   $ 7,799 $ 19,791 $ 21,477
Unrecognized compensation expense   200     $ 200  
Stock Options            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Unrecognized compensation expense, period of recognition (in years)         3 months 18 days  
Non-employee | Stock Options            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Option forfeitures in period (in shares)     5,862,866      
Stock based compensation expense   500   $ 500 $ 1,600 $ 2,800
Unrecognized compensation expense   $ 3,100     $ 3,100  
Unrecognized compensation expense, period of recognition (in years)         2 years  
Non-employee | Class B Common Stock            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Granted (in shares) 26,057,181          
Granted (in dollars per share) $ 8.58          
Non-employee | Class B Common Stock | Tranche One            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Expected to vest (in shares) 1,954,289          
Non-employee | Class B Common Stock | Stock Options            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Vesting period (in years) 15 years          
Performance period (in months) 15 months