Derivatives (Details 3) (Net Investment Hedges) In Millions, unless otherwise specified	3 Months Ended		1 Months Ended	3 Months Ended		12 Months Ended
	Mar. 31, 2013 USD ($)	Mar. 31, 2012 USD ($)	Jul. 31, 2007 Foreign Currency Denominated Debt EUR (€)	Mar. 31, 2013 Foreign Currency Denominated Debt USD ($)	Mar. 31, 2012 Foreign Currency Denominated Debt USD ($)	Dec. 31, 2007 Foreign Currency Denominated Debt EUR (€)
Net investment hedges
Pretax Gain (Loss) Recognized as Cumulative Translation within Other Comprehensive Income on Effective Portion of Instrument	$ (41)	$ (40)		$ (41)	$ (40)
Ineffective portion of gain (loss) on derivative and amount excluded from effectiveness testing recognized in income	0	0		0	0
Term of debt instrument			7 years			7 years
Face amount			€ 750			€ 275