Derivative Instruments (Details 5) (Details) - USD ($) $ in Millions |
3 Months Ended | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Mar. 31, 2017 |
Mar. 31, 2016 |
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| Derivative Instruments, Gain (Loss) [Line Items] | |||||||||||||
| Interest expense | $ 159 | $ 157 | |||||||||||
| 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] | (4) | (12) | ||||||||||
| Interest expense | [3],[4] | 0 | 1 | ||||||||||
| Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Hedging Instruments | |||||||||||||
| Derivative Instruments, Gain (Loss) [Line Items] | |||||||||||||
| Interest expense | [1],[2],[5] | $ (11) | $ (11) | ||||||||||
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