Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net income (loss)	$ (641,832)	$ (683,687)	$ 142,840
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax	(2,626)	10,894	(11,953)
Derivatives Qualifying as Hedges, Tax benefit	947	(3,921)	4,303
Derivatives Qualifying as Hedges, Adjustment, Net of Tax	(1,679)	6,973	(7,650)
Pension and Other Postretirement Benefit Plans, Total comprehensive income (loss) before tax	77,201	(21,291)	9,376
Pension and Other Postretirement Benefit Plans, Tax impact	(27,803)	7,686	(3,440)
Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	49,398	(13,605)	5,936
Available-for-sale Securities Adjustment, Total comprehensive income (loss) before tax	10,190	(3,000)	114
Available-for-sale Securities, Tax benefit	(3,710)	1,080	0
Available-for-sale Securities Adjustment, Net of Tax	6,480	(1,920)	114
Total other comprehensive income (loss)	54,199	(8,552)	(1,600)
Total comprehensive income (loss)	$ (587,633)	$ (692,239)	$ 141,240