Income Taxes - Components of Deferred Income Tax Amounts (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Income Tax Assets
Employee deferred compensation and other benefit obligations	$ 102,478	$ 105,096
Deferred Payroll Taxes (CARES Act)	27,086	0
Credits and net operating loss carryforwards	30,651	25,130
Stock-based compensation	3,637	7,805
Allowance for credit losses	5,272	7,944
Employee deferred compensation plan obligations	3,774	3,929
Operating lease liabilities	59,249	51,932
Other	13,361	10,256
Total deferred income tax assets	245,508	212,092
Deferred Income Tax Liabilities
Amortization of intangible assets	(24,163)	(22,009)
Property and equipment basis differences	(25,555)	(16,981)
Right-of-use assets	(49,833)	(44,448)
Other	(8,922)	(7,278)
Total deferred income tax liabilities	(108,473)	(90,716)
Valuation allowance	(24,132)	(21,618)
Total deferred income tax assets, net	$ 112,903	$ 99,758