Retirement Benefits (Details 12) (USD $) In Millions, unless otherwise specified	12 Months Ended					12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Asset backed	Dec. 31, 2010 Asset backed	Dec. 31, 2009 Asset backed	Dec. 31, 2011 High yield debt	Dec. 31, 2010 High yield debt	Dec. 31, 2011 Hedge funds	Dec. 31, 2010 Hedge funds	Dec. 31, 2011 Private equities	Dec. 31, 2010 Private equities	Dec. 31, 2011 Real estate	Dec. 31, 2010 Real estate	Dec. 31, 2010 Domestic Equity Securities	Dec. 31, 2011 Domestic Equity Securities
Changes in Fair Value of Plan Assets, Significant Unobservable Inputs (Table Amounts) [Abstract]
Beginning Balance	$ 4,952	$ 3,868	$ 4	$ 4	$ 4	$ 78	$ 59	$ 1,521	$ 1,282	$ 1,945	$ 1,651	$ 1,402	$ 870	$ 2	$ 2
Actual return on plan assets: [Abstract]
Assets still held at reporting date	172	443				(2)	18	(43)	120	19	200	198	103	2
Assets sold during the period	8	(9)						25		(13)		(4)	(9)
Purchases	1,386					10		413		503		460
Sales	(1,180)					(45)		(511)		(356)		(268)
Purchases, sales, and settlements		555							89		63		405	(2)
Changes in asset allocation mix		95					1		30		31		33
Ending Balance	$ 5,338	$ 4,952	$ 4	$ 4	$ 4	$ 41	$ 78	$ 1,405	$ 1,521	$ 2,098	$ 1,945	$ 1,788	$ 1,402	$ 2	$ 2