Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Accumulated other comprehensive income (loss), net of tax [Abstract]
Pension costs	$ 559,690		$ 559,690	$ 575,163
Postretirement costs	42,995		42,995	41,811
Deferred taxes on pension and OPEB costs	(225,704)		(225,704)	(230,161)
All other	148		148	150
Accumulated other comprehensive loss, net of tax	377,129		377,129	386,963
Other comprehensive income (loss), Before-Tax Amount [Abstract]
Amortization of pension and postretirement costs	7,145	3,335	14,290		6,669
All other	0	270	0		(480)
Other comprehensive income (loss)	7,145	3,605	14,290		6,189
Other comprehensive income (loss), Tax Expense/(Benefit) [Abstract]
Amortization of pension and postretirement costs	1,578	0	4,456		1,199
All other	0	270	0		0
Other comprehensive income (loss)	1,578	270	4,456		1,199
Other comprehensive income (loss), Net-of-Tax Amount [Abstract]
Amortization of pension and postretirement costs	5,567	3,335	9,834		5,470
All other	0	0	0		(480)
Other comprehensive income (loss)	$ 5,567	$ 3,335	$ 9,834	$ (162,404)	$ 4,990