Share-Based Compensation - Restricted Stock Units Transactions (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Weighted Average Grant Date Value
Stocks granted, fair value	$ 51.7	$ 24.1	$ 18.9
Restricted Stock Units
Restricted Stock Units
Unvested units - beginning balance (in shares)	1,200,000
Units granted (in shares)	200,000
Units vested (in shares)	(300,000)
Units forfeited (in shares)	(100,000)
Performance condition changes (in shares)	100,000
Unvested units - ending balance (in shares)	1,100,000	1,200,000
Weighted Average Grant Date Value
Unvested units - beginning balance (in dollars per share)	$ 99.46
Units granted (in dollars per share)	142.72
Units vested (in dollars per share)	133.00
Units forfeited (in dollars per share)	105.44
Performance condition changes (in dollars per share)	102.67
Unvested units - ending balance (in dollars per share)	$ 95.03	$ 99.46
Stocks granted, fair value	$ 32.3	$ 31.8	$ 59.7
Shares available for future grant (in shares)	3,200,000
Restricted Stock Units | Minimum
Weighted Average Grant Date Value
Stock vesting period	3 years
Restricted Stock Units | Maximum
Weighted Average Grant Date Value
Stock vesting period	4 years