Income Taxes - Deferred Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Allowance for doubtful accounts	$ 212	$ 259
Inventory reserves	1,353	967
Warranty liability	1,559	1,421
Deferred compensation	1,264	781
Earnout liabilities	516	694
Pension and retiree health benefit obligations	1,219	3,242
Accrued vacation	702	656
Medical claims reserve	78	189
State net operating losses	4,416	3,386
Other accrued liabilities	2,176	2,092
Valuation allowance for state net operating losses	(1,473)	(777)
Total deferred tax assets	12,022	12,910
Deferred tax liabilities:
Tax deductible goodwill and other intangibles	(53,565)	(47,163)
Accelerated depreciation	(6,547)	(5,084)
Other	(108)	68
Total deferred tax liabilities	(60,220)	(52,179)
Net deferred tax liabilities	(48,198)	(39,269)
State net operating losses	4,416	3,386
Valuation allowance for state net operating losses	1,473	$ 777
State
Deferred tax liabilities:
Operating loss carry forwards	$ 3,721