Stock-based compensation - Option Exchange Program (Details) - Option Exchange Program $ / shares in Units, $ in Millions		3 Months Ended
	Jan. 17, 2024 item shares	Mar. 31, 2024 USD ($)	Mar. 11, 2024 $ / shares shares
Stock-based compensation
Number of eligible stockholders | item	42
Number of shares reserved | shares	603,330		603,330
Exercise price of new options | $ / shares			$ 11.44
Stock-based compensation expense | $		$ 1.7