Schedule II - Valuation and Qualifying Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Employee Termination Benefits [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 63		$ 145		$ 13
Additions charged to expense	3		0		235
Payments	(36)		(82)		(103)
Ending Balance	30		63		145
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	167		239		293
Additions (reductions) to expense	(4)		4		(13)
Bad debt write-offs	(8)		(76)		(41)
Ending Balance	155		167		239
Deferred Income Tax Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	11,096	[1]	9,185	[1]	7,921	[1]
Additions to deferred income tax expense	5,471	[1]	2,216	[1]	1,454	[1]
Reduction of deferred income tax expense	(1,124)	[1]	(305)	[1]	(190)	[1]
Ending Balance	$ 15,443	[1]	$ 11,096	[1]	$ 9,185	[1]

[1] See also Note 14 to the Consolidated Financial Statements, beginning on page FS-43.