Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net income (loss)	$ (683,687)	$ 142,840	$ 159,394
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax	(14,523)	4,271	9,814
Net amount reclassified to income	918	1,665	101
Pension, postretirement and other post-employment benefits, reclassifications into net income	(13,605)	5,936	9,915
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	(1,924)	114	1,841
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	4
Unrealized gains (losses) on available-for-sale securities	(1,920)	114	1,841
Unrealized gains (losses) on derivatives	4,320	2,913	221
Reclassifications of (gains) losses into net income	2,653	(10,563)	1,514
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	6,973	(7,650)	1,735
Total other comprehensive income (loss)	(8,552)	(1,600)	13,491
Total comprehensive income (loss)	$ (692,239)	$ 141,240	$ 172,885