Income Taxes (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Estimated annual effective tax rate (as a percent)	28.50%	29.50%
Prior year tax adjustment expense (benefit)		$ 22,000,000
Tax correction expense (benefit)		55,000,000
Settlement benefit, interest and previously unrecognized tax benefits		(33,000,000)
Income tax examination, proposed liability increase/(decrease)	1,000,000,000
Income tax adjustment	$ 125,000,000