CONSOLIDATED INTERIM STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (40,612)	$ (29,357)	$ (76,049)	$ (52,630)	$ (111,581)
Other comprehensive loss, net of tax :
Change in foreign currency translation adjustments	56		56
Pension benefit plan	235		(235)		(1,505)
Total comprehensive loss	$ (40,321)	$ (29,357)	$ (76,228)	$ (52,630)	$ (113,086)