Derivative Financial Instruments (Pretax Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income - Cash Flow Hedges) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Derivative [Line Items]
Deferred gain (loss) recognized, total	$ (40)	$ (127)
Deferred (gain) loss reclassified to income, total	31	55
Total change in accumulated other comprehensive income	(9)	(72)
Foreign Exchange Risk [Member]
Derivative [Line Items]
Deferred gain (loss) recognized, foreign exchange risk	(40)	(29)
Deferred (gain) loss reclassified to income, foreign exchange risk	8	21
Total change in accumulated other comprehensive income	(32)	(8)
Interest Rate Risk [Member]
Derivative [Line Items]
Deferred gain (loss) recognized, interest rate risk	0	(98)
Deferred (gain) loss reclassified to income, interest rate risk	23	34
Total change in accumulated other comprehensive income	23	(64)
Loss related to a forecasted debt issuance		$ 18