Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (3,349)	$ (9,889)	$ 1,057
Other comprehensive income (loss)
Adoption of ASU 2018-02	(315)
Foreign currency translation adjustment	(3,501)	2,391	5,105
Reclassification adjustment for foreign currency translation included in net income (loss)		17,201
Pension liability, net of tax expense (benefit) of $25 in 2018, $14 in 2017, and ($95) in 2016	77	41	(169)
Total other comprehensive income (loss)	(3,739)	19,633	4,936
Comprehensive income (loss)	$ (7,088)	$ 9,744	$ 5,993