Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Taxes [Line Items]
Impact on effective tax rate due to additional expense associated with the American Taxpayer Relief Act of 2012			$ 17		$ 17
Effective tax rate	29.80%	28.30%		29.20%	28.90%
United States [Member]
Income Taxes [Line Items]
Open Tax Year				2007 and onward