v2.4.0.8
Income Taxes (Details) (USD $)
In Millions, unless otherwise specified
6 Months Ended
Jun. 30, 2014
Jun. 30, 2013
Dec. 31, 2013
Components of provision (benefit) for income taxes      
Annual effective tax rate (as a percent) 13.80% 21.70%  
Unrecognized tax benefits      
Unrecognized tax benefits, excluding interest and penalties $ 330   $ 326
Interest and penalties 169   176
Unrecognized tax benefits, including interest and penalties $ 499   $ 502