Derivative Financial Instruments and Hedging Activities Amounts Recognized in Net Income (Details) - Interest expense - net [Member] - Fair value hedging [Member] - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2015 |
Jun. 30, 2014 |
Jun. 30, 2015 |
Jun. 30, 2014 |
|
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Amounts recognized in net income | $ 0 | $ 0 | $ 0 | $ 0 |
| Fixed-to-floating interest rate swaps [Member] | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Amounts recognized in net income | (51) | 44 | (3) | 73 |
| Related long-term debt converted to floating interest rates by interest rate swaps [Member] | ||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Amounts recognized in net income | $ 51 | $ (44) | $ 3 | $ (73) |