Income Taxes - Reconciliation to Federal Statutory Income Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income taxes at U.S. federal statutory rate	$ (4,584)	$ 2,795	$ 8,922
Provision-to-return adjustments	433	325	(293)
State income tax, net of federal tax effect	458	5	944
Domestic production activities deduction	(280)	0	(670)
Tax credits	(393)	(349)	(414)
Uncertain tax positions	0	0	(1,219)
Transaction costs	0	1,312	0
Goodwill impairment	9,520	0	0
Stock-based compensation	1,155	0	0
Deferred impact of tax reform	(1,890)	0	0
Change in valuation allowance	(304)	0	0
Other	(182)	(35)	(122)
Total income tax provision	$ 3,933	$ 4,053	$ 7,148