Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Accumulated other comprehensive income (loss), net of tax [Abstract]
Pension costs	$ 552,895	$ 575,163		$ 552,895
Postretirement costs	43,709	41,811		43,709
Deferred taxes on pension and OPEB costs	(221,931)	(230,161)		(221,931)
All other	148	150		148
Accumulated other comprehensive loss, net of tax	374,821	386,963		374,821
Other comprehensive income (loss), Before-Tax Amount [Abstract]
Amortization of pension and postretirement costs	6,080		3,334	20,370	10,003
All other				0	(480)
Other comprehensive income (loss)				20,370	9,523
Other comprehensive income (loss), Tax Expense/(Benefit) [Abstract]
Amortization of pension and postretirement costs	3,772		0	8,228	1,199
All other				0	0
Other comprehensive income (loss)				8,228	1,199
Other comprehensive income (loss), Net-of-Tax Amount [Abstract]
Amortization of pension and postretirement costs	2,308		3,334	12,142	8,804
All other				0	(480)
Other comprehensive income (loss)	$ 2,308	$ (165,738)	$ 3,334	$ 12,142	$ 8,324