Retirement Benefits and Trusteed Assets (Details 8) (Other Postretirement Benefit Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other Postretirement Benefit Plans, Defined Benefit [Member]
Other Postretirement Costs [Line Items]
Service cost	$ 64	$ 61	$ 59
Interest cost	121	125	133
Expected return on plan assets	(94)	(74)	(55)
Net loss	55	54	72
Prior service cost	(26)	(4)	(6)
Net transition obligation	2	2	2
Net postretirement cost	$ 122	$ 164	$ 205