Stock-based Compensation - Summary Information about Stock Options Outstanding (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding, weighted average exercise price (in dollars per share)	$ 30.42	$ 25.56
$19.92-20.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit (in dollars per share)	19.92
Exercise price, upper range limit (in dollars per share)	$ 20
Options Outstanding	33,250
Options outstanding, weighted average remaining contractual life (in years)	1 year 1 month 24 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 19.92
Options Exercisable	33,250
Options exercisable, weighted average exercise price (in dollars per share)	$ 19.92
20.01-30.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit (in dollars per share)	20.01
Exercise price, upper range limit (in dollars per share)	$ 30
Options Outstanding	1,174,285
Options outstanding, weighted average remaining contractual life (in years)	7 years 3 months 15 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 25.50
Options Exercisable	666,915
Options exercisable, weighted average exercise price (in dollars per share)	$ 25.47
30.01-40.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit (in dollars per share)	30.01
Exercise price, upper range limit (in dollars per share)	$ 40
Options Outstanding	116,496
Options outstanding, weighted average remaining contractual life (in years)	6 years 26 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 32.13
Options Exercisable	116,496
Options exercisable, weighted average exercise price (in dollars per share)	$ 32.13
40.01-47.26
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit (in dollars per share)	40.01
Exercise price, upper range limit (in dollars per share)	$ 47.26
Options Outstanding	352,650
Options outstanding, weighted average remaining contractual life (in years)	9 years 2 months 5 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 47.26
Options Exercisable	0
Options exercisable, weighted average exercise price (in dollars per share)	$ 0.00
19.92-47.26
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower range limit (in dollars per share)	19.92
Exercise price, upper range limit (in dollars per share)	$ 47.26
Options Outstanding	1,676,681
Options outstanding, weighted average remaining contractual life (in years)	7 years 5 months 23 days
Options outstanding, weighted average exercise price (in dollars per share)	$ 30.42
Options Exercisable	816,661
Options exercisable, weighted average exercise price (in dollars per share)	$ 26.20