Share-Based Compensation Plans - Stock Options, Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding at January 1 (in shares) | shares	1,717
Granted (in shares) | shares	347
Exercised (in shares) | shares	(140)
Forfeited or expired (in shares) | shares	(62)
Options outstanding at December 31 (in shares) | shares	1,862
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options outstanding at January 1 (in dollars per share) | $ / shares	$ 70.47
Granted (in dollars per share) | $ / shares	74.72
Exercised (in dollars per share) | $ / shares	55.99
Forfeited or expired (in dollars per share) | $ / shares	72.62
Options outstanding at December 31 (in dollars per share) | $ / shares	$ 72.28
Summary of stock option activity
Vested and expected to vest at December 31 (in shares) | shares	1,803
Exercisable at December 31 (in shares) | shares	1,093
Vested and expected to vest at December 31, Weighted-Average Exercise Price (in dollars per share) | $ / shares	$ 72.25
Exercisable at December 31, Weighted-Average Exercise Price (in dollars per share) | $ / shares	$ 72.74
Outstanding, weighted average remaining contractual term	7 years
Vested and expected to vest at December 31 in years	7 years 2 months
Exercisable at December 31, in years	6 years 1 month
Options outstanding at December 31, Aggregate Intrinsic Value | $	$ 0
Vested and expected to vest at December 31, Aggregate Intrinsic Value | $	0
Exercisable at December 31, Aggregate Intrinsic Value | $	$ 0