Income Taxes - Components of Deferred Income Tax Amounts (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Income Tax Assets
Deferred compensation and other benefit obligations	$ 105,096	$ 87,513
Credits and net operating loss carryforwards	25,130	31,169
Stock-based compensation	7,805	9,535
Provision for bad debts	7,944	7,891
Workers’ compensation	3,929	3,580
Operating lease liabilities	51,932
Other	10,256	14,959
Total deferred income tax assets	212,092	154,647
Deferred Income Tax Liabilities
Amortization of intangible assets	(22,009)	(21,210)
Property and equipment basis differences	(16,981)	(9,761)
Right-of-use assets	(44,448)
Other	(7,278)	(10,319)
Total deferred income tax liabilities	(90,716)	(41,290)
Valuation allowance	(21,618)	(23,072)
Total deferred income tax assets, net	$ 99,758	$ 90,285