Earnings Per Share (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 Per Share [Abstract]
Anti-dilutive common stock equivalents excluded from computation (in shares)									0	0	0
Net income									$ 146,984	$ 109,522	$ 92,486
Less: Net (income) loss attributable to redeemable noncontrolling interest									(12,363)	4,374	(547)
Net income attributable to common stockholders	$ 36,728	$ 34,017	$ 31,333	$ 32,543	$ 25,561	$ 30,790	$ 29,959	$ 27,586	$ 134,621	$ 113,896	$ 91,939
Basic weighted average shares outstanding (in shares)	47,324	47,316	47,304	47,146	46,842	46,830	46,819	46,683	47,273	46,794	46,353
Dilutive potential shares from restricted stock units (in shares)									1,024	587	626
Diluted weighted average shares outstanding (in shares)	48,703	48,412	48,175	47,642	47,562	47,524	47,311	47,152	48,297	47,381	46,979
Basic earnings per share attributable to common stockholders (in dollars per share)	$ 0.78	$ 0.72	$ 0.66	$ 0.69	$ 0.55	$ 0.66	$ 0.64	$ 0.59	$ 2.85	$ 2.43	$ 1.98
Diluted earnings per share attributable to common stockholders (in dollars per share)	$ 0.75	$ 0.70	$ 0.65	$ 0.68	$ 0.54	$ 0.65	$ 0.63	$ 0.59	$ 2.79	$ 2.40	$ 1.96