Retirement Benefits and Trusteed Assets (OPEB - Postretirement Cost Inclusions) (Details) (Other Postretirement Benefit Plan, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other Postretirement Benefit Plan, Defined Benefit [Member]
Other Postretirement Costs [Line Items]
Service cost	$ 47	$ 68	$ 64
Interest cost	88	120	121
Expected return on plan assets	(110)	(92)	(94)
Amortization of Net Loss	64	80	55
Amortization of Prior Service Cost (Credit)	(131)	(27)	(26)
Amortization of net transition asset	0	2	2
Net pension or postretirement cost (benefit)	$ (42)	$ 151	$ 122