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
Allowance for Doubtful Accounts [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period,	$ 253	$ 272	$ 230
Provision Charged to Income	100	79	145
Deductions from reserves	(129)	(112)	(111)
Acquisitions	2	14	8
Balance at end of period,	226	253	272
Deferred Tax Assets Valuation Allowance [Member]
Valuation And Qualifying Accounts Disclosure [Line Items]
Provision Charged to Income	$ 72	$ 109	$ 129