Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (36,548)	$ (43,129)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	(1,694)	5,131
Defined benefit plans, net of tax:
Actuarial gain (loss) on benefit obligations and plan assets, net of tax benefit of $29 and tax provision of $401 for the years ended December 31, 2018 and 2017, respectively	(633)	1,424
Amortization of prior service cost, net of tax provision of $19 and $30 for the years ended December 31, 2018 and 2017, respectively	75	121
Effect of divestiture on other comprehensive income	(10,120)	0
Other comprehensive income (loss), net of tax	(12,372)	6,676
Comprehensive loss	$ (48,920)	$ (36,453)