Income Taxes (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
---|---|---|---|---|
Jun. 30, 2015 |
Jun. 30, 2014 |
Jun. 30, 2015 |
Jun. 30, 2014 |
|
Income Tax Disclosure [Line Items] | ||||
Effective income tax rate | 31.60% | 3.70% | 31.50% | 17.60% |
2007-2008 Federal Tax Audit Settlement [Member] | ||||
Income Tax Disclosure [Line Items] | ||||
Tax Adjustments, Settlements, and Unusual Provisions | $ 524 | |||
2011-2012 Federal Tax Audit Settlement [Member] | ||||
Income Tax Disclosure [Line Items] | ||||
Decrease (Increase) in Unrecognized Tax Benefits that is Reasonably Possible | $ 125 | $ 125 |