Stock-based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock Option Plans 2003 and 2013
Shares
Beginning balance (in shares)	1.6	1.7
Granted (in shares)	0.0	0.3
Exercised (in shares)	(0.3)	(0.2)
Forfeited (in shares)	0.0	(0.2)
Ending balance (in shares)	1.3	1.6
Options exercisable (in shares)	0.8
Weighted Average Exercise Price
Beginning balance weighted average exercise price (dollars per share)	$ 62.51	$ 58.93
Granted weighted average exercise price (dollars per share)	0	61.84
Exercised weighted average exercise price (in dollars per share)	52.49	28.20
Forfeited weighted average exercise price (dollars per share)	46.36	60.45
Ending balance weighted average exercise price (dollars per share)	65.18	$ 62.51
Options exercisable weighted average exercise price (dollars per share)	$ 64.72
Options outstanding weighted average remaining contractual term (in years)	6 years 4 months 6 days
Options outstanding weighted average intrinsic value	$ 20.8
Options exercisable weighted average remaining contractual term (in years)	5 years 8 months 23 days
Options exercisable weighted average intrinsic value	$ 18.4
Unvested Stock Options
Shares
Beginning balance (in shares)	0.6	0.7
Granted (in shares)	0.0	0.3
Forfeited (in shares)	0.0	(0.2)
Ending balance (in shares)	0.5	0.6