Employee Retirement Benefits (Pre- and Post-tax Amounts Recognized in AOCI) (Details) (USD $) In Millions, unless otherwise specified					12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2012 Pension Plans [Member]	Dec. 31, 2011 Pension Plans [Member]	Dec. 31, 2012 Other Postretirement Plans [Member]	Dec. 31, 2011 Other Postretirement Plans [Member]
Actuarial Loss
Beginning balance, January 1					$ 393	$ 218	$ 36	$ 42
Current year actuarial loss (gain)					135	184	8	(5)
Amortization					(29)	(9)	(1)	(1)
Ending balance, December 31					499	393	43	36
Prior Service Cost (Credit)
Beginning balance, January 1					4	6	(46)	(56)
Prior service credit due to curtailments					0	0	0	5
Amortization					(1)	(2)	6	5
Ending balance, December 31					3	4	(40)	(46)
Transition Obligation
Beginning balance, January 1					0	0	2	4
Amortization					0	0	(2)	(2)
Ending balance, December 31					0	0	0	2
Pre-Tax Amount Recorded in AOCI					502	397	3	(8)
After-Tax Amount Recorded in AOCI	505	389	214	[1]	502	397	3	(8)
Pre-tax amounts in AOCI that will be recognized in periodic benefit costs in the next fiscal year					$ 42		$ 3

[1] Includes a net increase of $3.4 billion from the adoption of the consolidation accounting guidance.