Consolidated Statements of Comprehensive Income (Loss) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net income (loss)	$ (70,049)	$ 1,409
Pension and Other Postretirement Benefit Plans, Total comprehensive income (loss) before tax	1,954	724
Pension and Other Postretirement Benefit Plans, Tax impact	(703)	(261)
Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	1,251	463
Available-for-sale Securities Adjustment, Total comprehensive income (loss) before tax	1,553	394
Available-for-sale Securities, Tax benefit	(559)	(142)
Available-for-sale Securities Adjustment, Net of Tax	994	252
Derivatives Qualifying as Hedges, Total comprehensive income (loss) before tax	(1,179)	10,287
Derivatives Qualifying as Hedges, Tax benefit	425	(3,702)
Derivatives Qualifying as Hedges, Adjustment, Net of Tax	(754)	6,585
Total other comprehensive income (loss)	1,491	7,300
Total comprehensive income (loss)	$ (68,558)	$ 8,709