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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings (numerator)
Net income (loss) attributable to common stockholders	$ 47,190	$ 38,060	$ 36,284	$ 31,716	$ 29,519	$ 30,908	$ 25,068	$ 18,526	$ 153,250	$ 104,021	$ (1,805)
Shares (denominator)
Weighted average common shares outstanding (basic)									50,787	49,841	48,824
Dilutive effect of stock options and stock awards outstanding									1,073	1,094
Adjusted weighted average common shares outstanding (diluted)									51,860	50,935	48,824
Earnings (loss) per share attributable to common stockholders
Basic	$ 0.92	$ 0.75	$ 0.72	$ 0.63	$ 0.59	$ 0.62	$ 0.50	$ 0.38	$ 3.02	$ 2.09	$ (0.04)
Diluted	$ 0.90	$ 0.73	$ 0.70	$ 0.62	$ 0.58	$ 0.61	$ 0.49	$ 0.37	$ 2.96	$ 2.04	$ (0.04)
Stock options and stock awards excluded from EPS calculation because their inclusion would be anti-dilutive									101	1,103	3,508