Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock option activity
Balance at the beginning of the period (in shares)	472,156	510,574	572,629
Granted (in shares)	0	0	35,800
Exercised (in shares)	(54,575)	(38,418)	(97,855)
Balance at the end of the period (in shares)	417,581	472,156	510,574
Vested and Expected to Vest (in shares)	416,567
Exercisable at the end of the period (in shares)	377,292
Weighted average exercise price
Balance at the beginning of the period (in dollars per share)	$ 30.41	$ 30.60	$ 24.42
Granted (in dollars per share)			85.99
Exercised (in dollars per share)	21.45	32.94	14.75
Balance at the end of the period (in dollars per share)	31.58	$ 30.41	$ 30.60
Vested and Expected to Vest (in dollars per share)	31.46
Exercisable at the end of the period (in dollars per share)	$ 26.72
Weighted average remaining contractual life
Outstanding at the beginning of period	2 years 284 days
Vested and Expected to Vest	2 years 281 days
Exercisable at the end of period	2 years 128 days
Aggregate intrinsic value
Outstanding at the end of the period	$ 24,597
Vested and Expected to Vest at the end of the period	24,587
Exercisable at the end of the period	$ 24,057