Stock-Based Compensation - Stock Option Activity (Details) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Options, Outstanding, Shares
Options, Beginning balance (shares) | shares	1.7
Shares, exercised (shares) | shares	(1.0)
Shares, forfeited and expired (shares) | shares	0.0
Options, Ending balance (shares) | shares	0.7
Shares, options exercisable (shares) | shares	0.7
Weighted average exercise price
Weighted-average exercise price, Beginning balance (USD per share) | $ / shares	$ 47.92
Weighted-average exercise price, exercised (USD per share) | $ / shares	163.99
Weighted-average exercise price, forfeited and expired (USD per share) | $ / shares	70.70
Weighted-average exercise price, Ending balance (USD per share) | $ / shares	55.73
Weighted-average exercise price, options exercisable (USD per share) | $ / shares	$ 55.12
Weighted-average remaining years of contractual term, Options outstanding	3 years 1 month 6 days
Weighted-average remaining years of contractual term, Options exercisable	3 years
Aggregate intrinsic value, options outstanding | $	$ 155.0
Aggregate intrinsic value, options exercisable | $	$ 151.0
Non Vested Options
Nonvested Options Outstanding
Options, Beginning balance (shares) | shares	0.1
Shares, vested (shares) | shares	0.0
Shares, forfeited (shares) | shares	(0.1)
Options, Ending balance (shares) | shares	0.0
Weighted-average grant-date fair value
Weighted-average grant-date fair value, Beginning balance (USD per share) | $ / shares	$ 113.02
Weighted-average grant-date fair value, vested (USD per share) | $ / shares	113.42
Weighted-average exercise price, forfeited (USD per share) | $ / shares	113.17
Weighted-average grant-date fair value, Beginning balance (USD per share) | $ / shares	$ 112.68
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Total unrecognized compensation expense related to nonvested options | $	$ 0.3
Weighted-average years to be recognized over	21 days