Fair Value Measurements Fair Value of Derivatives by Balance Sheet Location (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Derivatives Fair Value [Line Items]
Goodwill and intangible asset impairment losses in period	$ 423
Goodwill impairment charges	423	0
Goodwill	5,552		5,973
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net	(6)	(16)
Unamortized losses on senior notes	3		3
Unamortized gains on senior notes	61		64
Unrealized gain on interest rate cash flow hedges, pretax, AOCI	4		4
Derivative Assets	217		121
Derivative Liabilities	40		57
reduction of interest expense, related to amortization of previously terminated interest rate contracts	2
Designated as Hedging Instrument [Member]
Derivatives Fair Value [Line Items]
Derivative Instruments in Hedges, Assets, at Fair Value	185		88
Derivative Instruments in Hedges, Liabilities, at Fair Value	18		30
Designated as Hedging Instrument [Member] | Prepaid And Other Current Assets [Member]
Derivatives Fair Value [Line Items]
Derivative Instruments in Hedges, Assets, at Fair Value	71		25
Designated as Hedging Instrument [Member] | Other Long Term Assets [Member]
Derivatives Fair Value [Line Items]
Derivative Instruments in Hedges, Assets, at Fair Value	114		63
Designated as Hedging Instrument [Member] | Other current liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative Instruments in Hedges, Liabilities, at Fair Value	14		20
Designated as Hedging Instrument [Member] | Other Long Term Liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative Instruments in Hedges, Liabilities, at Fair Value	4		10
Not Designated as Hedging Instrument [Member] | Prepaid And Other Current Assets [Member]
Derivatives Fair Value [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	32		33
Not Designated as Hedging Instrument [Member] | Other current liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	$ 22		$ 27