Retirement Benefits and Trusteed Assets (Tables)

12 Months Ended

Dec. 31, 2012

Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]

Schedule of Net Benefit Costs [Table Text Block]

	2012			2011			2010
	(In millions)
Service cost	$	64		$	55		$	52
Interest cost	155			154			153
Expected return on plan assets	(166		)	(168		)	(171		)
Amortization of:
Net loss	124			99			70
Prior service cost	1			4			5
Settlements	2			2			—
Net pension cost	$	180		$	146		$	109

Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]

	2012			2011
	(In millions)
Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income
Net actuarial loss	$	289		$	437
Amortization of net actuarial loss	(125		)	(99		)
Amortization of prior service cost	(1		)	(4		)
Total recognized in Regulatory assets and Other comprehensive income	$	163		$	334
Total recognized in net periodic pension cost, Regulatory assets and Other comprehensive income	$	343		$	480
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income into net periodic benefit cost during next fiscal year
Net actuarial loss	$	143		$	120
Prior service cost	$	1		$	1

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

The following table reconciles the obligations, assets and funded status of the plan as well as the amount recognized as prepaid pension cost or pension liability in the Consolidated Statements of Financial Position at December 31:

	2012			2011
	(In millions)
Accumulated benefit obligation, end of year	$	3,307		$	2,963
Change in projected benefit obligation
Projected benefit obligation, beginning of year	$	3,196		$	2,899
Service cost	64			55
Interest cost	155			154
Actuarial loss	342			251
Settlements	2			2
Benefits paid	(174		)	(165		)
Projected benefit obligation, end of year	$	3,585		$	3,196
Change in plan assets
Plan assets at fair value, beginning of year	$	1,957		$	1,936
Actual return on plan assets	220			(18		)
Company contributions	208			204
Benefits paid	(174		)	(165		)
Plan assets at fair value, end of year	$	2,211		$	1,957
Funded status of the plan	$	(1,374	)	$	(1,239	)
Amount recorded as:
Current liabilities	$	(6	)	$	(8	)
Noncurrent liabilities	(1,368		)	(1,231		)
	$	(1,374	)	$	(1,239	)
Amounts recognized in Regulatory assets (see Note 8)
Net actuarial loss	$	1,805		$	1,645
Prior service cost	10			11
	$	1,815		$	1,656

Schedule of Expected Benefit Payments [Table Text Block]

At December 31, 2012, the benefits related to the Company’s qualified and nonqualified pension plans expected to be paid in each of the next five years and in the aggregate for the five fiscal years thereafter are as follows:

	(In millions)
2013	$	182
2014	187
2015	193
2016	200
2017	208
2018 - 2022	1,145
Total	$	2,115

Schedule of Assumptions Used [Table Text Block]

Assumptions used in determining the projected benefit obligation and net pension costs are listed below:

	2012	2011	2010
Projected benefit obligation
Discount rate	4.15%	5.00%	5.50%
Rate of compensation increase	4.20%	4.20%	4.00%
Net pension costs
Discount rate	5.00%	5.50%	5.90%
Rate of compensation increase	4.20%	4.00%	4.00%
Expected long-term rate of return on plan assets	8.25%	8.50%	8.75%

Schedule of Allocation of Plan Assets [Table Text Block]

Target allocations for plan assets as of December 31, 2012 are listed below:

U.S. Large Cap Equity Securities	22	%
U.S. Small Cap and Mid Cap Equity Securities	5
Non U.S. Equity Securities	20
Fixed Income Securities	25
Hedge Funds and Similar Investments	20
Private Equity and Other	8
	100	%

Pension Plans Fair Value Hierachy Level [Table Text Block]

Fair Value Measurements at December 31, 2012 and December 31, 2011 (a):

	December 31, 2012								December 31, 2011
(in Millions)	Level 1		Level 2		Level 3		Net Balance		Level 1		Level 2		Level 3		Net Balance
	(In millions)
Asset Category:
Short-term investments (b)	$	—	$	16	$	—	$	16	$	—	$	23	$	—	$	23
Equity securities
U.S. Large Cap (c)	478		31		—		509		440		27		—		467
U.S. Small/Mid Cap (d)	108		3		—		111		110		4		—		114
Non U.S. (e)	372		85		—		457		272		79		—		351
Fixed income securities (f)	61		491		—		552		61		448		—		509
Hedge Funds and Similar Investments (g)	147		56		238		441		132		40		205		377
Private Equity and Other (h)	—		—		125		125		—		—		116		116
Total	$	1,166	$	682	$	363	$	2,211	$	1,015	$	621	$	321	$	1,957

Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block]

Fair Value Measurements Using Significant Unobservable Inputs (Level 3):

	Year Ended December 31, 2012									Year Ended December 31, 2011
	Hedge Funds and Similar			Private Equity						Hedge Funds and Similar			Private Equity
	Investments			and Other			Total			Investments			and Other			Total
	(In millions)
Beginning Balance	$	205		$	116		$	321		$	206		$	118		324
Total realized/unrealized gains (losses):
Realized gains (losses)	13			(4		)	9			(3		)	4			1
Unrealized gains (losses)	(3		)	8			5			1			(21		)	(20		)
Purchases, sales and settlements:
Purchases	176			23			199			44			16			60
Sales	(153		)	(18		)	(171		)	(43		)	(1		)	(44		)
Ending Balance	$	238		$	125		$	363		$	205		$	116		$	321
The amount of total gains (losses) for the period attributable to the change in unrealized gains or losses related to assets still held at the end of the period	$	11		$	4		$	15		$	3		$	(20	)	$	(17	)

Schedule of Net Postretirement Costs [Table Text Block]

Net postretirement cost includes the following components:

	2012			2011			2010
	(In millions)
Service cost	$	51		$	49		$	47
Interest cost	91			91			95
Expected return on plan assets	(61		)	(62		)	(52		)
Amortization of:
Net loss	58			40			38
Prior service costs (credit)	(16		)	(15		)	2
Net transition asset	2			2			2
Net postretirement cost	$	125		$	105		$	132

Schedule of Postretirement Plan Amounts Recognized in Regulatory Assets [Table Text Block]

	2012			2011
	(In millions)
Other changes in plan assets and APBO recognized in Regulatory assets
Net actuarial loss (gain)	$	(14	)	$	139
Amortization of net actuarial loss	(58		)	(40		)
Prior service cost (credit)	(207		)	(3		)
Amortization of prior service credit	16			15
Amortization of transition asset	(2		)	(2		)
Total recognized in Regulatory assets	$	(265	)	$	109
Total recognized in net periodic pension cost and Regulatory assets	$	(140	)	$	214
Estimated amounts to be amortized from Regulatory assets into net periodic benefit cost during next fiscal year
Net actuarial loss	$	50		$	55
Prior service credit	$	(69	)	$	(16	)
Net transition obligation	$	—		$	2

Schedule of Other Postretirement Benefit Plans Disclosures [Table Text Block]

	2012			2011
Change in accumulated postretirement benefit obligation	(In millions)
Accumulated postretirement benefit obligation, beginning of year	$	1,868		$	1,742
Service cost	51			49
Interest cost	91			91
Plan amendments	(207		)	(3		)
Actuarial loss	12			60
Medicare Part D subsidy	5			4
Benefits paid	(68		)	(75		)
Accumulated postretirement benefit obligation, end of year	$	1,752		$	1,868
Change in plan assets
Plan assets at fair value, beginning of year	$	651		$	682
Actual return on plan assets	88			(17		)
Company contributions	95			66
Benefits paid	(78		)	(80		)
Plan assets at fair value, end of year	$	756		$	651
Funded status, end of year	$	(996	)	$	(1,217	)
Amount recorded as:
Non-current liabilities	$	(996	)	$	(1,217	)
Amounts recognized in Regulatory assets (see Note 8)
Net actuarial loss	$	560		$	633
Prior service cost	(244		)	(53		)
Net transition obligation	—			2
	$	316		$	582

Schedule of Expected Benefit Payments OPEB [Table Text Block]

	(In millions)
2013	$	78
2014	82
2015	87
2016	91
2017	97
2018-2022	556
	$	991

Assumptions used to Determine Projected Benefit Obligations and Net OPEB Costs [Table Text Block]

Assumptions used in determining the projected benefit obligation and net benefit costs are listed below:

	2012		2011		2010
Projected benefit obligation
Discount rate	4.15	%	5.00	%	5.50	%
Health care trend rate pre- and post- 65	7.00	%	7.00	%	7.00	%
Ultimate health care trend rate	5.00	%	5.00	%	5.00	%
Year in which ultimate reached	2019		2016		2016
Net benefit costs
Discount rate	5.00	%	5.50	%	5.90	%
Expected long-term rate of return on plan assets	8.25	%	8.75	%	8.75	%
Health care trend rate pre- and post- 65	7.00	%	7.00	%	7.00	%
Ultimate health care trend rate	5.00	%	5.00	%	5.00	%
Year in which ultimate reached	2020		2019		2016

Schedule of Allocation of Plan Assets OPEB [Table Text Block]

Target allocations for plan assets as of December 31, 2012 are listed below:

U.S. Equity Securities	21	%
Non U.S. Equity Securities	20
Fixed Income Securities	25
Hedge Funds and Similar Investments	20
Private Equity and Other	14
	100	%

Other Postretirement Benefit Plans Hierachy Level [Table Text Block]

Fair Value Measurements at December 31, 2012 and December 31, 2011(a):

	December 31, 2012								December 31, 2011
	Level 1		Level 2		Level 3		Net Balance		Level 1		Level 2		Level 3		Net Balance
Asset Category:	(In millions)
Short-term investments (b)	$	1	$	1	$	—	$	2	$	1	$	8	$	—	$	9
Equity securities
U.S. Large Cap (c)	122		2		—		124		116		10		—		126
U.S. Small/Mid Cap (d)	70		—		—		70		46		4		—		50
Non U.S. (e)	151		4		—		155		116		10		—		126
Fixed income securities (f)	25		162		—		187		15		156		—		171
Hedge Funds and Similar Investments (g)	68		15		78		161		53		14		63		130
Private Equity and Other (h)	—		—		57		57		—		—		39		39
Total	$	437	$	184	$	135	$	756	$	347	$	202	$	102	$	651

Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets OPEB [Table Text Block]

Fair Value Measurements Using Significant Unobservable Inputs (Level 3):

	Year Ended December 31, 2012									Year Ended December 31, 2011
	Hedge Funds and Similar Investments			Private Equity and Other			Total			Hedge Funds and Similar Investments			Private Equity and Other			Total
	(In millions)
Beginning Balance	$	63		$	39		$	102		$	52		$	36		$	88
Total realized/unrealized gains (losses):
Realized gains (losses)	4			(7		)	(3		)	(1		)	1			—
Unrealized gains (losses)	—			9			9			2			(14		)	(12		)
Purchases, sales and settlements:
Purchases	56			25			81			45			31			76
Sales	(45		)	(9		)	(54		)	(35		)	(15		)	(50		)
Ending Balance	$	78		$	57		$	135		$	63		$	39		$	102
The amount of total gains (losses) for the period attributable to the change in unrealized gains or losses related to assets still held at the end of the period	$	4		$	1		$	5		$	3		$	(11	)	$	(8	)