Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (10,118)	$ 2,167	$ (20,517)	$ (4,681)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	2,814	(1,070)	4,126	872
Defined benefit pension plan, net of tax:
Amortization of deferred loss, net of tax provision of $13 for the three months ended June 30, 2016; net of tax provision of $25 for the six months ended June 30, 2016	0	49	0	97
Amortization of prior service cost, net of tax provision of $8 for each of the three months ended June 30, 2017 and 2016; net of tax provision of $15 for each of the six months ended June 30, 2017 and 2016	31	30	60	60
Other comprehensive income (loss), net of tax	2,845	(991)	4,186	1,029
Comprehensive income (loss)	$ (7,273)	$ 1,176	$ (16,331)	$ (3,652)