Stock-based compensation - Classification of expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Share-Based Compensation
Stock-based compensation expense	$ 9,475	$ 8,846
Stock options
Share-Based Compensation
Stock-based compensation expense	5,733	5,614
Restricted and performance stock units
Share-Based Compensation
Stock-based compensation expense	3,742	3,232
Research and development
Share-Based Compensation
Stock-based compensation expense	4,226	3,298
Selling, general and administrative
Share-Based Compensation
Stock-based compensation expense	$ 5,249	$ 5,548