Income Taxes - Significant Components of Federal and State Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Allowance for doubtful accounts	$ 3,109	$ 2,672
Deferred compensation	6,601	8,532
Accrued insurance claims	3,665	5,862
Non-deductible reserves	567	1,257
Amortization of intangibles	162	624
Other	662	858
Deferred tax assets	14,766	19,805
Deferred tax liabilities:
Expensing of housekeeping supplies	(4,678)	(6,752)
Depreciation of property and equipment	(1,745)	(2,568)
Other	(845)	(663)
Deferred tax liabilities	(7,268)	(9,983)
Net deferred tax assets	$ 7,498	$ 9,822