Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Income tax
Net UTB impacting the effective tax rate	$ 355		$ 355		$ 394
Interest and penalties related to unrecognized tax benefits, expense (benefit) recognized on a gross basis	5	(13)	3	(9)
Interest and penalties related to unrecognized tax benefits, accrued on a gross basis	60		60		52
Effective tax rate (as a percent)			27.80%	29.10%
Change in effective income tax rate from prior reporting period to current reporting period (as a percent)			(1.30%)
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)				2.80%
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)			1.50%
Deferred tax assets valuation allowance	$ 129		$ 129		$ 128