Retirement Benefits and Trusteed Assets (Pension Plan - Other Changes in Plan Assets and Benefit Obligations recognized in Reg Assets and OCI) (Details) (Pension Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ (418)	$ 289
Amortization of net actuarial loss	(148)	(125)
Amortization of prior service cost	(1)	(1)
Regulatory Assets and Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax	(567)	163
Total recognized in net periodic pension cost, Regulatory assets and Other comprehensive income	(383)	343
Net actuarial loss	106	143
Prior service credit	$ 1	$ 1