Stock-Based Compensation - RSUs and PSUs (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restricted stock units
Number of RSUs
Balance at the beginning of the period (in shares)			270,052
Granted (in shares)			140,747
Forfeited (in shares)			(2,061)
Vested (in shares)			(114,078)
Balance at the end of the period (in shares)	294,660		294,660
Weighted Average Grant Date Fair Value
Balance at the beginning of the year (in dollars per shares)			$ 41.70
Granted (in dollars per share)			47.30
Forfeited (in dollars per share)			42.64
Vested (in dollars per share)			32.90
Balance at the end of the year (in dollars per shares)	$ 47.78		$ 47.78
Aggregate market value of RSUs vested	$ 1,556	$ 1,279	$ 5,691	$ 12,833
PSUs
Number of RSUs
Balance at the beginning of the period (in shares)			90,020
Granted (in shares)			51,839
Forfeited (in shares)			(561)
Vested (in shares)			0
Balance at the end of the period (in shares)	141,298		141,298
Weighted Average Grant Date Fair Value
Balance at the beginning of the year (in dollars per shares)			$ 55.06
Granted (in dollars per share)			60.36
Forfeited (in dollars per share)			56.57
Vested (in dollars per share)			0
Balance at the end of the year (in dollars per shares)	$ 57.00		$ 57.00