Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts	$ 5,224	$ 9,735
Accrued employee benefits	4,147	5,532
Stock compensation	663	1,004
Accrued self-insurance	2,157	2,762
Acquisition costs	2,064	1,781
Net operating loss carry forward	1,299	1,880
Intangible asset impairment	21	38
Uncertain tax position-state tax portion	0	63
Uncertain tax position-interest expense	0	90
Other	91	155
Capital loss carryforward	12	154
Valuation allowance	(44)	(44)
Deferred tax assets	15,634	23,150
Deferred tax liabilities:
Amortization of intangible assets	(35,955)	(45,622)
Tax depreciation in excess of book depreciation	(5,988)	(8,397)
Prepaid expenses	(623)	(817)
Non-accrual experience accounting method	(534)	(255)
Deferred tax liabilities	(43,100)	(55,091)
Net deferred tax liability	$ (27,466)	$ (31,941)