Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income (Loss)	$ (64,049)	$ (11,473)	$ (78,683)	$ 238,433
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent [Abstract]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	24,980	7,921	113,641	75,080
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	13,246	(6,459)	40,400	80,280
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax [Abstract]
Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	(24,354)	(47,809)	(56,595)	(153,597)
Other Comprehensive Income (Loss), Net of Tax	13,872	(46,347)	97,446	1,763
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(50,177)	(57,820)	18,763	240,196
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	(398)	(105)	(942)	(134)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ (49,779)	$ (57,715)	$ 19,705	$ 240,330