Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (131,845)	$ (111,581)	$ (80,682)
Other comprehensive loss, net of tax :
Change in foreign currency translation adjustments	10
Pension benefit plan	(388)	(1,505)
Total comprehensive loss	$ (132,223)	$ (113,086)	$ (80,682)