v3.26.3
Stock-based compensation - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 6 Months Ended
Aug. 07, 2026
Apr. 01, 2026
Jul. 09, 2018
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Mar. 31, 2026
Stock-Based Compensation                
Unrecognized compensation cost related to unvested common stock options       $ 39.1   $ 39.1    
Expenses expected to be recognized over a weighted average remaining period           2 years 8 months 12 days    
Weighted average grant-date fair value (in dollars per share)           $ 7.07 $ 5.81  
Value of stock options exercised           $ 4.6 $ 0.0  
Weighted average grant date fair value           29.7 20.9  
Total fair value of shares vested           $ 16.0 $ 13.1  
Stock options                
Stock-Based Compensation                
Exercise price for persons holding ten percent of voting power (as a percent)       100.00%   100.00%    
Exercise price for persons holding more than ten percent of voting power (as a percent)       110.00%   110.00%    
Share based payment award expiration period           10 years    
Share based payment award vesting period           4 years    
Unrecognized compensation cost related to unvested common stock options       $ 23.0   $ 23.0    
Expenses expected to be recognized over a weighted average remaining period           2 years 7 months 6 days    
Stock options | Maximum                
Stock-Based Compensation                
Expiration period for persons holding ten percent of voting power           5 years    
Stock options | Minimum                
Stock-Based Compensation                
Expiration period for persons holding more than ten percent of voting power           10 years    
RSUs                
Stock-Based Compensation                
Share based payment award vesting period           4 years    
RSUs | Share-Based Payment Arrangement, Tranche One                
Stock-Based Compensation                
Share based payment award vesting period           1 year    
PSUs                
Stock-Based Compensation                
Vesting percentage           100.00%    
Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested in period, fair value $ 3.2              
Granted (in shares)       0 0 0 0  
Pre-funded warrants                
Stock-Based Compensation                
Common stock, authorized (in shares)               14,058,153
2017 Plan                
Stock-Based Compensation                
Number of shares available for grant     2,520,247          
2018 Plan                
Stock-Based Compensation                
Shares authorized (in shares)     3,617,968          
Number of shares available for grant       3,819,646   3,819,646    
Share based payment award percentage of outstanding shares     4.00%          
Additional shares authorized (in shares)   3,871,003            
ESPP                
Stock-Based Compensation                
Share based payment award percentage of outstanding shares     1.00%          
Additional shares authorized (in shares)   697,224 697,224          
Common stock reserved for issuance (in shares)   4,799,623 348,612          
Out Of Plan Inducement Grants | RSUs                
Stock-Based Compensation                
Granted (in shares)           100,000 333,130  
Out Of Plan Inducement Grants | Nonqualified Stock Options                
Stock-Based Compensation                
Granted (in shares)           150,000 202,945