Fair Value Measurements (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Apr. 30, 2011	Dec. 31, 2010
Notional amount of interest rate fair value hedge derivatives					$ 1,000,000,000
Fair value of cross currency swaps designated as cash flow hedges	300,000,000		300,000,000			100,000,000
Other comprehensive income, unrealized gain (loss) on derivatives arising during period, before tax	36,000,000	(200,000,000)	100,000,000	(400,000,000)
Forward Interest Rate Swaps [Member]
Interest rate fair value hedge liability at fair value						100,000,000
Notional amount of interest rate fair value hedge derivatives						1,400,000,000
Interest Rate Swap [Member]
Interest rate fair value hedge liability at fair value	400,000,000		400,000,000			300,000,000
Notional amount of interest rate fair value hedge derivatives	8,000,000,000		8,000,000,000
Cross Currency Swap [Member]
Proceeds from other debt			$ 2,400,000,000