Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Tax expense (benefit) at U.S. federal income tax rate	$ (16,093)	$ 9,706	$ 5,175
State income taxes, net of federal income tax effect	(307)	883	447
Federal and state deferred tax rate change	1,135	(5,119)	0
Transition tax	(924)	5,323	0
Effect of non-US operations	(2,424)	(2,228)	(781)
Nontaxable contingent liability fair value changes and goodwill impairment	11,254	237	3,578
Research and development credit	(40)	(38)	(140)
Change in valuation allowances	3,973	2,103	2,206
Prior year provision to return adjustment	942	(581)	(137)
Write-off of deferred taxes and tax receivables	431	70	193
Change in valuation allowances	468	932	293
Effective Income Tax Rate Reconciliation, Tax Reform Global Intangible Low-taxed Income	1,124	0	0
Prior year provision to return adjustment	$ (461)	$ 11,288	$ 10,834