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	$	82		$	69		$	64
Interest cost	204			202			202
Expected return on plan assets	(244		)	(246		)	(258		)
Amortization of:
Net loss	176			142			100
Prior service cost	—			3			4
Special termination benefits	2			2			—
Net pension cost	$	220		$	172		$	112

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	$	395		$	619
Amortization of net actuarial loss	(178		)	(142		)
Amortization of prior service cost	—			(3		)
Total recognized Regulatory assets and Other comprehensive income	$	217		$	474
Total recognized in net periodic pension cost, Regulatory assets and Other comprehensive income	$	437		$	646
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	$	202		$	171

Schedule of Defined Benefit Plans Disclosures [Table Text Block]

	2012			2011
	(In millions)
Accumulated benefit obligation, end of year	$	4,349		$	3,881
Change in projected benefit obligation
Projected benefit obligation, beginning of year	$	4,195		$	3,785
Service cost	82			69
Interest cost	204			202
Actuarial loss	474			355
Special termination benefits	2			2
Benefits paid	(228		)	(218		)
Projected benefit obligation, end of year	$	4,729		$	4,195
Change in plan assets
Plan assets at fair value, beginning of year	$	2,886		$	2,913
Actual return on plan assets	325			(18		)
Company contributions	240			209
Benefits paid	(228		)	(218		)
Plan assets at fair value, end of year	$	3,223		$	2,886
Funded status of the plans	$	(1,506	)	$	(1,309	)
Amount recorded as:
Current liabilities	$	(8	)	$	(11	)
Noncurrent liabilities	(1,498		)	(1,298		)
	$	(1,506	)	$	(1,309	)
Amounts recognized in Accumulated other comprehensive loss, pre-tax
Net actuarial loss	$	205		$	202
Prior service (credit)	(2		)	(3		)
	$	203		$	199
Amounts recognized in Regulatory assets (see Note 11)
Net actuarial loss	$	2,413		$	2,201
Prior service cost	7			7
	$	2,420		$	2,208

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	$	236
2014	242
2015	252
2016	260
2017	269
2018-2022	1,485
	$	2,744

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 2011 (a):

	December 31, 2012								December 31, 2011
	Level 1		Level 2		Level 3		Net Balance		Level 1		Level 2		Level 3		Net Balance
	(In millions)
Asset Category:
Short-term investments (b)	$	—	$	24	$	—	$	24	$	—	$	33	$	—	$	33
Equity securities															—
U.S. Large Cap (c)	688		44		—		732		640		40		—		680
U.S. Small/Mid Cap (d)	153		5		—		158		159		5		—		164
Non U.S (e)	530		120		—		650		392		114		—		506
Fixed income securities (f)	87		765		—		852		88		703		—		791
Hedge Funds and Similar Investments (g)	209		80		339		628		190		58		296		544
Private Equity and Other (h)	—		—		179		179		—		—		168		168
Total	$	1,667	$	1,038	$	518	$	3,223	$	1,469	$	953	$	464	$	2,886

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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 Investments			Private Equity and Other			Total			Hedge Funds and Similar Investments			Private Equity and Other			Total
	(In millions)
Beginning Balance at January 1	$	296		$	168		$	464		$	304		$	174		$	478
Total realized/unrealized gains (losses):
Realized gains (losses)	18			(6		)	12			(4		)	6			2
Unrealized gains (losses)	(5		)	12			7			1			(30		)	(29		)
Purchases, sales and settlements:
Purchases	250			33			283			64			23			87
Sales	(220		)	(28		)	(248		)	(69		)	(5		)	(74		)
Ending Balance at December 31	$	339		$	179		$	518		$	296		$	168		$	464
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	$	16		$	6		$	22		$	4		$	(28	)	$	(24	)

Schedule of Net Postretirement Costs [Table Text Block]

Net postretirement cost includes the following components:

	2012			2011			2010
	(In millions)
Service cost	$	68		$	64		$	61
Interest cost	120			121			125
Expected return on plan assets	(92		)	(94		)	(74		)
Amortization of:
Net loss	80			55			54
Prior service credit	(27		)	(26		)	(4		)
Net transition asset	2			2			2
Net postretirement cost	$	151		$	122		$	164

Schedule of Postretirement Plan Amounts Recognized in Regulatory Assets and Other Comprehensive Income [Table Text Block]

	2012			2011
	(In millions)
Other changes in plan assets and APBO recognized in Regulatory assets and Other comprehensive income (in millions)
Net actuarial (gain) loss	$	(34	)	$	195
Amortization of net actuarial loss	(80		)	(55		)
Prior service credit	(264		)	(4		)
Amortization of prior service credit	27			26
Amortization of transition asset	(2		)	(2		)
Total recognized in Regulatory assets and Other comprehensive income	$	(353	)	$	160
Total recognized in net periodic pension cost, Regulatory assets and Other comprehensive income	$	(202	)	$	282
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income into net periodic benefit cost during next fiscal year (in millions)
Net actuarial loss	$	69		$	78
Prior service credit	$	(91	)	$	(27	)
Net transition obligation	$	—		$	2

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

The following table reconciles the obligations, assets and funded status of the plans including amounts recorded as accrued postretirement cost in the Consolidated Statements of Financial Position at December 31:

	2012			2011
	(In millions)
Change in accumulated postretirement benefit obligation
Accumulated postretirement benefit obligation, beginning of year	$	2,470		$	2,305
Service cost	68			64
Interest cost	120			121
Plan amendments	(264		)	(4		)
Actuarial loss	5			80
Medicare Part D subsidy	6			6
Benefits paid	(90		)	(102		)
Accumulated postretirement benefit obligation, end of year	$	2,315		$	2,470
Change in plan assets
Plan assets at fair value, beginning of year	$	985		$	1,029
Actual return on plan assets	131			(22		)
Company contributions	140			111
Benefits paid	(103		)	(133		)
Plan assets at fair value, end of year	$	1,153		$	985
Funded status, end of year	$	(1,162	)	$	(1,485	)
Amount recorded as:
Current liabilities	$	(2	)	$	(1	)
Noncurrent liabilities	$	(1,160	)	$	(1,484	)
	$	(1,162	)	$	(1,485	)
Amounts recognized in Accumulated other comprehensive loss, pre-tax
Net actuarial loss	$	40		$	47
Prior service credit	(14		)	(20		)
Net transition asset	(1		)	(1		)
	$	25		$	26
Amounts recognized in Regulatory assets (See Note 11)
Net actuarial loss	$	727		$	835
Prior service cost	(302		)	(60		)
Net transition obligation	1			3
	$	426		$	778

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. Domestic 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 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	$	2	$	—	$	3	$	—	$	13	$	—	$	13
Equity securities:
U.S. Large Cap (c)	189		3		—		192		175		15		—		190
U.S. Small/Mid Cap (d)	105		—		—		105		70		6		—		76
Non U.S (e)	230		7		—		237		176		14		—		190
Fixed income securities (f)	38		247		—		285		24		236		—		260
Hedge Funds and Similar Investments (g)	102		24		119		245		80		21		95		196
Private Equity and Other (h)	—		—		86		86		—		—		60		60
Total	$	665	$	283	$	205	$	1,153	$	525	$	305	$	155	$	985

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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 at January 1	$	95		$	60		$	155		$	79		$	55		$	134
Total realized/unrealized gains (losses):
Realized gains (losses)	6			(11		)	(5		)	(1		)	2			1
Unrealized gains (losses)	—			14			14			2			(22		)	(20		)
Purchases, sales and settlements:
Purchases	86			36			122			68			48			116
Sales	(68		)	(13		)	(81		)	(53		)	(23		)	(76		)
Ending Balance at December 31	$	119		$	86		$	205		$	95		$	60		$	155
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	$	6		$	2		$	8		$	5		$	(16	)	$	(11	)