Earnings Per Share - Components of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income	$ 16,625				$ 25,196	$ 22,806
Net loss attributable to redeemable noncontrolling interest	370				606
Net income	$ 16,995	$ 8,807	$ 13,796	$ 9,010	$ 25,802	22,806
Net income attributable to common stockholders			$ 13,796			$ 22,806
Weighted average common shares outstanding - basic (in shares)	48,792,280		48,388,696		48,758,922	48,281,068
Dilutive effect of stock options and restricted stock units (in shares)	1,759,352		1,895,294		1,684,604	1,963,316
Weighted average common shares outstanding - diluted (in shares)	50,551,632		50,283,990		50,443,526	50,244,384
Weighted average common shares outstanding — diluted (C)
Basic (in dollars per share)	$ 0.35		$ 0.29		$ 0.53	$ 0.47
Diluted (in dollars per share)	$ 0.34		$ 0.27		$ 0.51	$ 0.45