Income Taxes - Provision for Income Taxes Attributable to Income from Continuing Operations (Details) - USD ($) $ 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
Income Tax Disclosure [Abstract]
Tax at U.S. federal statutory rates									$ 21,733	$ 19,507	$ 16,766
State taxes (net of federal benefit)									5,354	4,774	3,745
Business meals and entertainment — non-deductible									458	987	915
Change in valuation allowance									176	932	264
Reserves for uncertain tax positions									(1,290)	(263)	(1,124)
Share-based compensation									(2,394)	(4,773)	(3,260)
Non-deductible expenses									787	713	785
Other, net									317	(37)	176
Total income tax expense from continuing operations	$ (1,979)	$ 7,060	$ 6,607	$ 13,453	$ (3,164)	$ 6,069	$ 5,322	$ 13,613	$ 25,141	$ 21,840	$ 18,267
Effective income tax rate									24.30%	23.50%	22.90%