Retirement Benefits (Details 11) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	$ 22,286	$ 21,013
Level 1
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	5,190	5,446
Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	11,758	10,615
Level 3
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	5,338	4,952
Cash & cash equivalents
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,603	1,203
Cash & cash equivalents | Level 1
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	75	92
Cash & cash equivalents | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,528	1,111
U.S. Treasuries
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,872	1,381
U.S. Treasuries | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,872	1,381
Other U.S. Government Agency Securities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	965	715
Other U.S. Government Agency Securities | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	965	715
Non-U.S. Government Securities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	324	224
Non-U.S. Government Securities | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	324	224
Corporate debt
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	3,686	3,512
Corporate debt | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	3,686	3,512
Asset backed
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	529	762
Asset backed | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	525	758
Asset backed | Level 3
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	4	4
High yield debt
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,018	1,070
High yield debt | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	977	992
High yield debt | Level 3
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	41	78
Bank loans
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	150	115
Bank loans | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	150	115
Hedge funds
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,405	1,521
Hedge funds | Level 3
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,405	1,521
Private equities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	2,098	1,945
Private equities | Level 3
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	2,098	1,945
Real estate
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,788	1,402
Real estate | Level 3
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,788	1,402
Other
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	14	(64)
Other | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	14	(64)
Domestic Equity Securities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	3,852	3,953
Domestic Equity Securities | Level 1
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	3,849	3,948
Domestic Equity Securities | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1	3
Domestic Equity Securities | Level 3
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	2	2
International Equity Securities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	2,982	3,274
International Equity Securities | Level 1
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	1,266	1,406
International Equity Securities | Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets at the end of the year	$ 1,716	$ 1,868