Pension and OPEB - Periodic Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	$ (8,212)	$ (12,106)
Amortization of actuarial gain	(25,188)	(27,005)
Other Comprehensive Income (Loss), Finalization of Pension and Non-Pension Postretirement Plan Valuation, Net of Tax	27,115
Net periodic (benefit) cost	44,091	14,899
Deferred Income Taxes	160,750		148,104
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	5,706	5,153
Interest cost	8,843	9,378
Expected return on plan assets	(12,144)	(11,627)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(408)	(408)
Amortization of actuarial gain	12,175	12,263
Other Comprehensive Income (Loss), Finalization of Pension and Non-Pension Postretirement Plan Valuation, Net of Tax	27,115	0
Net periodic (benefit) cost	41,287	14,759
Pension Contributions	18,560
Total anticipated contributions to pension trust	50,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	4,849	5,200
Interest cost	29,619	35,527
Expected return on plan assets	0	0
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(7,804)	(11,599)
Amortization of actuarial gain	17,595	20,345
Other Comprehensive Income (Loss), Finalization of Pension and Non-Pension Postretirement Plan Valuation, Net of Tax	0	0
Net periodic (benefit) cost	44,259	49,473
Defined Benefit Plan, Benefits Paid	41,922
Salary OPEB Amendment [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic (benefit) cost	6,760
Defined Benefit Plan, Plan Amendments	29,916
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	35,261
Deferred Income Taxes	$ 21,770