Retirement Benefits (Details 9) (Other Postretirement Benefits [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other Postretirement Benefits [Member]
Components of the other postretirement benefit plans net periodic cost
Service cost	$ 21	$ 25	$ 26
Interest cost	92	100	113
Expected return on plan assets	(64)	(63)	(61)
Net amortization	20	20	25
Total change	69	82	103
Summary of estimation of future benefit payments and subsidy receipts based on assumptions used to measure the accumulated benefit obligation for postretirement plans
Benefit Payments for 2012	110
Benefit Payments for 2013	116
Benefit Payments for 2014	122
Benefit Payments for 2015	128
Benefit Payments for 2016	133
Benefit Payments for 2017 to 2021	691
Subsidy Receipts for 2012	(10)
Subsidy Receipts for 2013	(12)
Subsidy Receipts for 2014	(13)
Subsidy Receipts for 2015	(15)
Subsidy Receipts for 2016	(16)
Subsidy Receipts for 2017 to 2021	(90)
Total for 2012	100
Total for 2013	104
Total for 2014	109
Total for 2015	113
Total for 2016	117
Total for 2017 to 2021	$ 601