Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accumulated other comprehensive income (loss), net of tax [Abstract]
Pension costs	$ 575,163	$ 349,264
Postretirement costs	41,811	13,369
Deferred taxes on pension and OPEB costs	(230,161)	(132,752)
All other	150	(332)
Accumulated other comprehensive loss, net of tax	386,963	229,549
Other comprehensive income (loss), before tax [Abstract]
Net actuarial gain (loss)	(263,732)	9,123	(35,759)
Amortization of pension and postretirement costs	9,391	23,955	24,179
All other	(482)	424	(74)
Other comprehensive income (loss)	(254,823)	33,502	(11,654)
Other comprehensive income (loss), tax [Abstract]
Net actuarial gain (loss)	(100,815)	4,774	(10,149)
Amortization of pension and postretirement costs	3,590	12,536	6,862
All other	(184)	222	0
Other comprehensive income (loss)	(97,409)	17,532	(3,287)
Other comprehensive income (loss), net of tax [Abstract]
Net actuarial gain (loss)	(162,917)	4,349	(25,610)
Amortization of pension and postretirement costs	5,801	11,419	17,317
All other	(298)	202	(74)
Other comprehensive income (loss)	$ (157,414)	$ 15,970	$ (8,367)