Share-Based Compensation - Restricted Stock Options Activity and Status (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-Based Compensation
Share-based compensation expense (benefit) before taxes	$ 25.6	$ (12.4)
RSUs
Share-Based Compensation
Number of shares of common stock entitled to recipient upon vesting (in shares)	1
Share-based compensation expense (benefit) before taxes	$ 15.5	12.2
Number of RSUs
Unvested at beginning of the period (in shares)	964,759
Granted (in shares)	391,725
Vested (in shares)	(139,219)
Forfeited (in shares)	(4,882)
Unvested at the end of the period (in shares)	1,212,383
Weighted Average Grant Date Fair Value
Unvested at beginning of the period (in dollars per share)	$ 210.35
Granted (in dollars per share)	235.18
Vested (in dollars per share)	186.49
Forfeited (in dollars per share)	208.45
Unvested at the end of the period (in dollars per share)	$ 221.12
Unrecognized compensation cost	$ 204.7
Weighted average remaining vesting period	2 years 10 months 24 days
RSUs with Performance Conditions
Share-Based Compensation
Awards granted in period, fair value	$ 47.5	32.2
Share-based compensation expense (benefit) before taxes	$ 2.1	$ 0.2
Number of RSUs
Granted (in shares)	200,000	200,000