Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (13,860)	$ (6,855)	$ (34,377)	$ (11,536)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	(929)	685	3,197	1,557
Defined benefit pension plan, net of tax:
Amortization of deferred loss, net of tax provision of $12 for the three months ended September 30, 2016; net of tax provision of $37 for the nine months ended September 30, 2016	0	49	0	146
Amortization of prior service cost, net of tax provision of $7 and $8 for the three months ended September 30, 2017 and 2016, respectively; net of tax provision of $22 and $23 for the nine months ended September 30, 2017 and 2016, respectively	31	30	91	90
Other comprehensive income (loss), net of tax	(898)	764	3,288	1,793
Comprehensive loss	$ (14,758)	$ (6,091)	$ (31,089)	$ (9,743)