Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Income tax
Net UTB impacting the effective tax rate	$ 319		$ 319		$ 394
Interest and penalties related to unrecognized tax benefits, expense (benefit) recognized on a gross basis	(3)	4		(5)
Interest and penalties related to unrecognized tax benefits, accrued on a gross basis	58		58		52
Effective tax rate (as a percent)			28.10%	28.30%
Change in effective income tax rate from prior reporting period to current reporting period (as a percent)			(0.20%)
Reduction in deferred tax asset, elimination of subsidy				84
Change in effective tax rate as a result of the Medicare Modernization Act (as a percent)				1.80%
Change in effective tax rate from prior reporting period to current reporting period as a result of international tax rates and other items (as a percent)			1.60%
Deferred tax assets valuation allowance	$ 128		$ 128		$ 128