Condensed Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net loss	$ (113,195)us-gaap_NetIncomeLoss	$ (124,139)us-gaap_NetIncomeLoss
Derivative instruments
Comprehensive income (loss) before tax	5,045	(229)
Income tax benefit (provision)	(1,817)	82
Derivatives Qualifying as Hedges, Adjustment, Net of Tax	3,228	(147)
Pension, postretirement and other post-employment benefits
Comprehensive income (loss) before tax	294	(1,847)
Income tax benefit (provision)	(105)	665
Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	189	(1,182)
Available-for-sale securities
Comprehensive income (loss) before tax	291	(2,033)
Income tax benefit (provision)	(104)	732
Available-for-sale Securities Adjustment, Net of Tax	187	(1,301)
Total other comprehensive income (loss)	3,604	(2,630)
Total comprehensive loss	$ (109,591)us-gaap_ComprehensiveIncomeNetOfTax	$ (126,769)us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Other Comprehensive Income

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount before tax, after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities, attributable to parent entity. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount before tax, after reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans, attributable to parent entity.

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Amount before tax, after reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss), attributable to parent entity.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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