Earnings Per Share - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings (numerator)
Net income (loss) attributable to common stockholders	$ 29,735	$ 27,152	$ 21,033	$ 20,168	$ 47,190	$ 38,060	$ 36,284	$ 31,716	$ 98,088	$ 153,250	$ 104,021
Shares (denominator)
Weighted average common shares outstanding (basic)									51,004	50,787	49,841
Dilutive effect of stock options and stock awards outstanding									1,129	1,073	1,094
Adjusted weighted average common shares outstanding (diluted)									52,133	51,860	50,935
Earnings (loss) per share attributable to common stockholders
Basic	$ 0.60	$ 0.52	$ 0.41	$ 0.39	$ 0.90	$ 0.75	$ 0.72	$ 0.63	$ 1.92	$ 3.02	$ 2.09
Diluted	$ 0.59	$ 0.51	$ 0.40	$ 0.38	$ 0.90	$ 0.73	$ 0.70	$ 0.62	$ 1.88	$ 2.96	$ 2.04
Stock options and stock awards excluded from EPS calculation because their inclusion would be anti-dilutive									137	101	1,103