Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net loss	$ (72,206)	$ (435,424)	$ (142,255)	$ (434,015)
Derivatives Qualifying as Hedges, Total comprehensive income (loss) before tax	(391)	738	(1,570)	11,025
Derivatives Qualifying as Hedges, Tax benefit	143	(265)	568	(3,967)
Derivatives Qualifying as Hedges, Adjustment, Net of Tax	(248)	473	(1,002)	7,058
Pension and Other Postretirement Benefit Plans, Total comprehensive income (loss) before tax	1,750	(5,600)	3,704	(4,876)
Pension and Other Postretirement Benefit Plans, Tax impact	(630)	2,016	(1,333)	1,755
Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	1,120	(3,584)	2,371	(3,121)
Available-for-sale Securities Adjustment, Total comprehensive income (loss) before tax	4,959	97	6,512	491
Available-for-sale Securities, Tax benefit	(1,788)	(35)	(2,347)	(177)
Available-for-sale Securities Adjustment, Net of Tax	3,171	62	4,165	314
Total other comprehensive income	4,043	(3,049)	5,534	4,251
Total comprehensive loss	$ (68,163)	$ (438,473)	$ (136,721)	$ (429,764)