Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 6,844	$ 3,114
Other comprehensive income (loss)
Adoption of ASU 2018-02	(315)
Foreign currency translation adjustment	(1,720)	901
Pension liability, net of tax expense of $67 in 2018	201
Total other comprehensive income (loss)	(1,834)	901
Comprehensive income	$ 5,010	$ 4,015