Share-Based Payments - Stock Options (Details) - Stock options - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Awards
Outstanding at the beginning of the period (in shares)	1.8
Granted (in shares)	0.3
Exercised (in shares)	(0.1)
Expired (in shares)	(0.1)
Outstanding at the end of the period (in shares)	1.9	1.8
Expected to vest at end of period (in shares)	0.7
Exercisable at end of period (in shares)	1.2
Weighted- average exercise price per unit
Weighted-average exercise price of shares outstanding, beginning of the period (in dollars per share)	$ 66.32
Weighted-average exercise price of shares granted (in dollars per share)	44.97
Weighted-average exercise price of shares exercised (in dollars per share)	44.10
Weighted-average exercise price of shares expired (in dollars per share)	78.49
Weighted-average exercise price of shares outstanding, end of the period (in dollars per share)	63.15	$ 66.32
Weighted-average exercise price of shares expected to vest (in dollars per share)	49.27
Weighted-average exercise price of shares exercisable (in dollars per share)	$ 70.61
Weighted- average remaining contractual life (years)
Weighted-average remaining contractual life at beginning of period	4 years 9 months 18 days	4 years 6 months
Weighted-average remaining contractual life at end of period	4 years 9 months 18 days	4 years 6 months
Weighted-average remaining contractual life, expected to vest	8 years 1 month 6 days
Weighted-average remaining contractual life, exercisable	3 years
Aggregate intrinsic value
Aggregate intrinsic value of shares outstanding, beginning	$ 0.2
Aggregate intrinsic value of shares outstanding, ending	0.6	$ 0.2
Aggregate intrinsic value of shares expected to vest	0.4
Aggregate intrinsic value of shares exercisable	$ 0.2