CONSOLIDATED INTERIM STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (33,628)	$ (26,023)	$ (109,677)	$ (78,653)	$ (111,581)
Other comprehensive loss, net of tax :
Change in foreign currency translation adjustments	8		64
Pension benefit plan	(409)		(644)		(1,505)
Total comprehensive loss	$ (34,029)	$ (26,023)	$ (110,257)	$ (78,653)	$ (113,086)