Share-based Compensation - Stock Options Activity Rollforward (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares
Number of Shares
Outstanding at beginning of period (shares) | shares	360
Granted (shares) | shares	60
Exercised (shares) | shares	(130)
Forfeited / Cancelled (shares) | shares	(10)
Outstanding at end of period (shares) | shares	280
Vested and expected to vest (shares) | shares	280
Exercisable at end of year (shares) | shares	120
Weighted-average Exercise Price
Outstanding at beginning of period (usd per share) | $ / shares	$ 57.95
Granted (usd per share) | $ / shares	118.41
Exercised (usd per share) | $ / shares	55.39
Forfeited / Cancelled (usd per share) | $ / shares	69.10
Outstanding at end of period (usd per share) | $ / shares	71.38
Vested and expected to vest at end of year (usd per share) | $ / shares	70.55
Exercisable at end of year (usd per share) | $ / shares	$ 54.20
Outstanding at end of year, aggregate intrinsic value | $	$ 25.1
Vested and expected to vest at end of year, aggregate intrinsic value | $	12.5
Exercisable at end of year, aggregate intrinsic value | $	$ 24.5
Outstanding at end of year, weighted average contractual term	6 years 8 months 12 days
Vested and expected to vest at end of year, weighted average contractual term	6 years 7 months 6 days
Exercisable at end of year, weighted average contractual term	5 years 1 month 6 days