Retirement Benefits (Details 5) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Amounts Recognized in the Consolidated Statements of financial position [Abstract]
Non-current assets	$ 153	$ 320
Non-current liability	(4,079)	(3,089)
Pension Benefits
Amounts Recognized in the Consolidated Statements of financial position [Abstract]
Non-current assets	112	275
Current liability	(104)	(94)
Non-current liability	(2,797)	(1,920)
Medical and Life Benefits
Amounts Recognized in the Consolidated Statements of financial position [Abstract]
Non-current assets	41	45
Current liability	(48)	(48)
Non-current liability	$ (1,282)	$ (1,169)