v3.19.1

Debt Senior Unsecured Notes (Details) - USD ($) $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Dec. 31, 2018
Debt Instrument [Line Items] |  |  |
Long-term Debt | $ 10,682 |  | $ 10,156
Gain (Loss) on Extinguishment of Debt | 4 | $ 0 |
Senior Unsecured Notes 2023 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Long-term Debt | 1,228 |  | 1,227
Senior Unsecured Notes 2024 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Long-term Debt | 589 |  | 599
Senior Unsecured Notes 2025 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Long-term Debt | 1,172 |  | 1,210
Unsecured Debt [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Debt Instrument, Repurchased Face Amount, Cumulative | 438 |  |
Debt Instrument, Repurchased Face Amount | 48 |  |
Long-term Debt | 2,989 |  | $ 3,036
Debt Instrument, Repurchase Amount | 44 |  |
Gain (Loss) on Extinguishment of Debt | 4 |  |
Debt Instrument, Repurchase Amount, Cumulative | $ 399 |  |

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