Derivative Instruments (Details 4) (Details) - USD ($) $ in Millions |
12 Months Ended | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
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| Derivative Instruments, Gain (Loss) [Line Items] | ||||||||||||||||
| Interest expense | $ 631 | $ 628 | $ 645 | |||||||||||||
| Interest Rate Contract [Member] | ||||||||||||||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||||||||||||||
| Gains (Loss) Recognized in OCI (Effective Portion) | [1],[2] | 41 | 23 | (2) | ||||||||||||
| Interest expense | [3],[4] | 2 | 3 | 11 | ||||||||||||
| Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Contract [Member] | ||||||||||||||||
| Derivative Instruments, Gain (Loss) [Line Items] | ||||||||||||||||
| Interest expense | [1],[2],[5],[6] | $ (43) | $ (47) | $ (46) | ||||||||||||
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