Share-based payments (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Time-based shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Performance-based shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate fair value at grant date	$ 13.7	$ 11.4
Granted (in shares)	223,000	278,000
Average grant price (in usd per share)	$ 61.44	$ 40.93