Earnings Per Share - Schedule of Dilutive Effect of Stock Options RSUs and PSAs (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net Income	$ 16,671	$ 13,692	$ 42,705	$ 35,806
Basic	18,873	18,666	18,783	18,807
Dilutive effect of stock options, RSUs, and performance shares	433	358	473	411
Weighted-average number of diluted shares outstanding during the period	19,306	19,024	19,256	19,218
Basic	$ 0.88	$ 0.73	$ 2.27	$ 1.90
Diluted	$ 0.86	$ 0.72	$ 2.22	$ 1.86