Stock-Based Compensation (Stock Based Compensation Textuals) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2015 |
Jun. 30, 2014 |
Jun. 30, 2015 |
Jun. 30, 2014 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Allocated Share-based Compensation Expense | $ 7 | $ 8 | $ 16 | $ 17 |
| Allocated Share Based Compensation Expense Liability Classified Share-Based Awards | (6) | $ 4 | (4) | 5 |
| Restricted Stock [Member] | ||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||
| Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized | $ 38 | 38 | ||
| Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition | 1 year 6 months | |||
| Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value | $ 33 | $ 30 | ||