Schedule II Valuation and Qualiying Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation Allowances and Reserves, Beginning Balance	$ 3,132		$ 3,113		$ 3,056
Valuation Allowances and Reserves, Charged to Cost and Expense	60		(92)		112
Valuation Allowance Charged To Accumulated Other Comprehensive Income	191		204		(45)
Valuation Allowances and Reserves, Deductions	(4)		(82)		0
Valuation Allowances and Reserves, Adjustments	14		(11)		(10)
Valuation Allowances and Reserves, Ending Balance	3,393		3,132		3,113
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation Allowances and Reserves, Beginning Balance	97		106		110
Valuation Allowances and Reserves, Charged to Cost and Expense	20		14		15
Valuation Allowance Charged To Accumulated Other Comprehensive Income	0		0		0
Valuation Allowances and Reserves, Deductions	(20)	[1]	(19)	[1]	(16)	[1]
Valuation Allowances and Reserves, Adjustments	2		(4)		(3)
Valuation Allowances and Reserves, Ending Balance	$ 99		$ 97		$ 106

[1] Note: (a) Accounts receivable charged off.