CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement Of Income and Comprehensive Income [Abstract]
Net income (loss)	$ 3,634	$ (32,511)
Other comprehensive income (loss):
Pension adjustment and reclassification adjustment, net of taxes	135	127
Foreign currency translation	42	692
Unrealized loss on securities, net of taxes	(15)	(9)
Comprehensive income (loss)	$ 3,796	$ (31,701)