| **Indebtedness - Maturities of Debt Schedule (Details) $ in Millions** | Dec. 31, 2016 USD ($) |
|------------------------------------------------------------------------|-----------------------|
| **Total debt**                                                         |                  |
| 2017                                                                   | $ 132                 |
| 2018                                                                   | 753                   |
| 2019                                                                   | 26                    |
| 2020                                                                   | 12                    |
| 2021                                                                   | 524                   |
| Thereafter                                                             | $ 1,571               |

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.
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