v3.7.0.1

Debt Senior Unsecured Notes (Details) - USD ($) $ in Millions | Jun. 30, 2017 | Dec. 31, 2016
--- | --- | ---
Debt Instrument [Line Items] |  |
Long-term Debt | $ 11,741 | $ 12,046
Senior Unsecured Notes 2023 [Member] |  |
Debt Instrument [Line Items] |  |
Long-term Debt | 1,238 | 1,237
Senior Unsecured Notes 2024 [Member] |  |
Debt Instrument [Line Items] |  |
Long-term Debt | 643 | 643
Senior Unsecured Notes 2025 [Member] |  |
Debt Instrument [Line Items] |  |
Long-term Debt | 1,533 | 1,532
Unsecured Debt [Member] |  |
Debt Instrument [Line Items] |  |
Long-term Debt | $ 3,414 | $ 3,412

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