Share-based compensation - Schedule of Long-Term Incentive Plan (LTIP) Linked to Other Performance Conditions (Details) - LTIP awards linked to other performance conditions - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Shares
Outstanding, beginning of period (in shares)	327,085	309,589	306,342
Granted (in shares)	362,963	108,499	105,860
Vested (in shares)	(113,118)	(62,778)	(71,807)
Increased above target (cancelled) due to performance (in shares)	(91,521)	(13,153)	36,505
Cancelled (in shares)	(43,277)	0	0
Forfeited (in shares)	(3,165)	(15,072)	(67,311)
Outstanding, end of period (in shares)	438,967	327,085	309,589
Weighted-Average Grant-Date Fair Value Per Share
Outstanding, beginning of period (in dollars per share)	$ 39.44	$ 39.50	$ 38.42
Granted (in dollars per share)	13.09	42.41	41.31
Vested (in dollars per share)	34.93	48.07	37.68
Increased above target (cancelled) due to performance (in dollars per share)	41.31	36.59	35.75
Cancelled (in dollars per share)	41.86	0	0
Forfeited (in dollars per share)	42.06	42.19	37.35
Outstanding, end of period (in dollars per share)	$ 18.17	$ 39.44	$ 39.50
Total weighted-average grant-date fair value of shares granted (in millions)	$ 4.8	$ 4.6	$ 4.4