Derivative Instruments (Details 5) (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
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| Derivative Instruments, Gain (Loss) [Line Items] | |||||||||||||||
| Interest expense | $ 158 | $ 159 | $ 472 | $ 471 | |||||||||||
| Interest Rate Hedging Instruments | |||||||||||||||
| Derivative Instruments, Gain (Loss) [Line Items] | |||||||||||||||
| Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net | [1],[2] | 18 | (4) | 0 | 4 | ||||||||||
| Interest expense | [3] | 0 | 1 | 1 | 2 | ||||||||||
| Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Hedging Instruments | |||||||||||||||
| Derivative Instruments, Gain (Loss) [Line Items] | |||||||||||||||
| Interest expense | [1],[2],[4],[5] | $ (11) | $ (12) | $ (33) | $ (36) | ||||||||||
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