Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net loss	$ (206,702)	$ (113,195)
Derivative instruments
Comprehensive income (loss) before tax	(224)	5,045
Income tax benefit (provision)	81	(1,817)
Derivatives qualifying as hedges, adjustment, net of tax	(143)	3,228
Pension, postretirement and other post-employment benefits
Comprehensive income (loss) before tax	(1,338)	294
Income tax benefit (provision)	481	(105)
Pension and other postretirement benefit plans, adjustment, net of tax	(857)	189
Available-for-sale securities
Comprehensive income (loss) before tax	2,903	291
Income tax benefit (provision)	(1,043)	(104)
Available-for-sale securities adjustment, net of tax	1,860	187
Total other comprehensive income (loss)	860	3,604
Total comprehensive loss	$ (205,842)	$ (109,591)