Share-Based Compensation Plans - Options Outstanding and Exercisable (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
$27-$49
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, lower range limit (in dollars per share)	$ 27
Exercise price range, upper range limit (in dollars per share)	49
$50-$73
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, lower range limit (in dollars per share)	50
Exercise price range, upper range limit (in dollars per share)	73
$74-$85
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, lower range limit (in dollars per share)	74
Exercise price range, upper range limit (in dollars per share)	85
$86-$123
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, lower range limit (in dollars per share)	86
Exercise price range, upper range limit (in dollars per share)	$ 123
Stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, shares (in shares) | shares	672
Options outstanding, weighted-average remaining contractual life	5 years 10 months 24 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 85
Options exercisable, shares (in shares) | shares	401
Options exercisable, weighted-average exercise price (in dollars per share)	$ 76
Stock option | $27-$49
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, shares (in shares) | shares	35
Options outstanding, weighted-average remaining contractual life	1 year 9 months 18 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 39
Options exercisable, shares (in shares) | shares	35
Options exercisable, weighted-average exercise price (in dollars per share)	$ 39
Stock option | $50-$73
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, shares (in shares) | shares	67
Options outstanding, weighted-average remaining contractual life	2 years 9 months 18 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 55
Options exercisable, shares (in shares) | shares	67
Options exercisable, weighted-average exercise price (in dollars per share)	$ 55
Stock option | $74-$85
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, shares (in shares) | shares	309
Options outstanding, weighted-average remaining contractual life	5 years 9 months 18 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 77
Options exercisable, shares (in shares) | shares	223
Options exercisable, weighted-average exercise price (in dollars per share)	$ 77
Stock option | $86-$123
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, shares (in shares) | shares	261
Options outstanding, weighted-average remaining contractual life	7 years 4 months 24 days
Options outstanding, weighted-average exercise price (in dollars per share)	$ 109
Options exercisable, shares (in shares) | shares	76
Options exercisable, weighted-average exercise price (in dollars per share)	$ 105