v3.26.1
Stock-based compensation - stock option rollforward information (Details) - Common stock
$ / shares in Units, shares in Millions, $ in Millions
 6 Months Ended
Jun. 30, 2026
USD ($)
$ / shares
shares
Number of options outstanding  
Beginning balance (in shares) | shares 11.7
Granted (in shares) | shares 6.7
Exercised (in shares) | shares 0.0
Forfeited (in shares) | shares (4.8)
Ending balance (in shares) | shares 13.6
Weighted average exercise price per outstanding option  
Beginning balance (in dollars per share) | $ / shares $ 21.18
Granted (in dollars per share) | $ / shares 10.69
Exercised (in dollars per share) | $ / shares 0
Forfeited (in dollars per share) | $ / shares 17.14
Ending balance (in dollars per share) | $ / shares $ 17.33
Other information about options outstanding  
Aggregate intrinsic value | $ $ 1.0
Weighted average remaining term 5 years 10 months 24 days
Information about options expected to vest and exercisable  
Options expected to vest, number (in shares) | shares 6.2
Options expected to vest, weighted average exercise price per option (in dollars per share) | $ / shares $ 11.53
Options expected to vest, aggregate intrinsic value | $ $ 1.0
Options expected to vest, weighted average remaining term 9 years 6 months
Options exercisable, number (in shares) | shares 7.4
Options exercisable, weighted average exercise price per option (in dollars per share) | $ / shares $ 22.16
Options exercisable, aggregate intrinsic value | $ $ 0.0
Options exercisable, weighted average remaining term 2 years 10 months 24 days