CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement Of Income and Comprehensive Income [Abstract]
Net loss	$ (38,942)	$ (35,173)	$ (120,139)	$ (61,680)
Other comprehensive (loss) income:
Pension adjustment and reclassification adjustment, net of taxes	126	126	380	376
Foreign currency translation	(144)	(598)	712	(1,474)
Unrealized gain (loss) on securities, net of taxes	7	(27)	(2)	(29)
Comprehensive loss	$ (38,953)	$ (35,672)	$ (119,049)	$ (62,807)