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Employee Benefits - Schedule of Fair Value of U.S Plan Assets (Details) - Pension Plan - U.S. - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | $ 2,066 | $ 1,796 | $ 1,958
Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 77 | 130 |
Equity securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 195 | 384 |
Equity derivatives |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 22 | (14) |
Equity investments, Pooled funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 583 | 285 |
Corporate bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 128 | 111 |
Government and agency bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 199 | 126 |
Asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 3 | 2 |
Fixed Income Investments, Pooled Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 545 | 417 |
Real estate and REITS |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 133 | 78 |
Alternative investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 181 | 277 |
Quoted Prices in Active Markets for Identical Assets (Level 1) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 434 | 687 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 77 | 130 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 195 | 384 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity derivatives |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity investments, Pooled funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Government and agency bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 162 | 95 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed Income Investments, Pooled Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Real estate and REITS |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 78 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Alternative investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 190 | 130 |
Significant Other Observable Inputs (Level 2) | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Equity securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Equity derivatives |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 22 | (14) |
Significant Other Observable Inputs (Level 2) | Equity investments, Pooled funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Corporate bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 128 | 111 |
Significant Other Observable Inputs (Level 2) | Government and agency bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 37 | 31 |
Significant Other Observable Inputs (Level 2) | Asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 3 | 2 |
Significant Other Observable Inputs (Level 2) | Fixed Income Investments, Pooled Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Real estate and REITS |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Other Observable Inputs (Level 2) | Alternative investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Equity securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Equity derivatives |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Equity investments, Pooled funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Corporate bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Government and agency bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Fixed Income Investments, Pooled Funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Real estate and REITS |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | 0 | 0 |
Significant Unobservable Inputs (Level 3) | Alternative investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined benefit plan, plan assets | $ 0 | $ 0 |

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