Share-Based Compensation - Restricted shares (Details) - Restricted Stock - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Restricted shares outstanding
Outstanding at the beginning of the period (in shares))	185,000
Granted (in shares)	96,368	103,465	112,203
Vested (in shares)	(67,000)
Forfeited (in shares)	(14,000)
Outstanding at the end of the period (in shares)	200,000	185,000
Weighted-Average Grant-Date Fair Value
Outstanding at the beginning of the period (in dollars per share)	$ 140.56
Granted (in dollars per share)	83.32
Vested (in dollars per share)	131.64
Forfeited (in dollars per share)	122.85
Outstanding at the end of the period (in dollars per share)	$ 117.2	$ 140.56
Aggregate value at grant date	$ 8.0	$ 16.6	$ 14.8
Fair value of vested shares	8.9	$ 8.4	$ 6.3
Total future compensation cost related to unvested awards	$ 15.3
Recognition period	2 years 2 months 15 days
Maximum
Share-Based Compensation
Vesting period	4 years