Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (1,645)	$ (64,049)	$ 89,424	$ (78,683)
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	184,154	24,980	185,475	113,641
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	39,151	13,246	(20,032)	40,400
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Net Amount to be Transferred	(19,510)	(24,354)	3,754	(56,595)
Other Comprehensive Income (Loss), Net of Tax	203,795	13,872	169,197	97,446
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	202,150	(50,177)	258,621	18,763
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest	0	(398)	0	(942)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 202,150	$ (49,779)	$ 258,621	$ 19,705