Retirement Benefits and Trusteed Assets (OPEB - Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Change in Accumulated PostRetirement Benefit Obligation [Line Items]
Regulatory Liabilities	$ (1,164)	$ (1,120)
Regulatory Assets	2,863	4,417
Other Postretirement Benefit Plan, Defined Benefit [Member]
Change in Accumulated PostRetirement Benefit Obligation [Line Items]
Benefit obligation, beginning of year	2,315	2,470
Service cost	47	68	64
Interest cost	88	120	121
Plan amendments	(218)	(264)
Actuarial loss	(267)	5
Medicare Part D subsidy	1	6
Benefits paid	(88)	(90)
Benefit obligation, end of year	1,878	2,315	2,470
Defined Benefit Plan, Fair Value of Plan Assets	1,527	1,153	985
Actual return on plan assets	196	131
Company contributions	264	140
Benefits paid	(86)	(103)
Funded status of the plans	(351)	(1,162)
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	(1)	(2)
Noncurrent liabilities	(350)	(1,160)
Pension and Other Postretirement Defined Benefit Plans, Liabilities	(351)	(1,162)
Net actuarial loss recognized in other comprehensive loss	29	40
Prior service cost (credit) recognized in other comprehensive income	(10)	(14)
Net transition obligation	0	(1)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	19	25
Net actuarial loss recognized in regulatory assets	321	727
Prior service cost recognized in regulatory assets	(393)	(302)
Net transition obligation	0	1
Regulatory Liabilities	(72)
Regulatory Assets		$ 426