v2.4.0.6
Income Taxes (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Operating Loss Carryforwards [Line Items]    
Income tax expense $ 279 $ 96
Effective tax rate 30.00% 24.00%
Federal statutory income tax rate 35.00% 35.00%