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	$ (664)	$ (549)
Regulatory Assets	2,288	3,510
Other Postretirement Benefit Plans, Defined Benefit [Member]
Change in Accumulated PostRetirement Benefit Obligation [Line Items]
Projected benefit obligation, beginning of year	1,752	1,868
Service cost	35	51	49
Interest cost	67	91	91
Plan amendments	(159)	(207)
Actuarial loss	(200)	12
Medicare Part D subsidy	1	5
Benefits paid	(66)	(68)
Projected benefit obligation, end of year	1,430	1,752	1,868
Defined Benefit Plan, Fair Value of Plan Assets	1,061	756	651
Actual return on plan assets	131	88
Company contributions	239	95
Benefits paid	(65)	(78)
Funded status of the plan	(369)	(996)
Noncurrent liabilities	(369)	(996)
Net actuarial loss	255	560
Prior service cost	(303)	(244)
Regulatory Liabilities	(48)
Regulatory Assets		$ 316