Employee Benefits - Schedule of Fair Value of U.S Plan Assets (Details) - Pension Plan - U.S. - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	$ 2,276	$ 2,066	$ 1,796
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	79	77
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	207	195
Equity derivatives
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	62	22
Equity investments, Pooled funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	640	583
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	167	128
Government and agency bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	233	199
Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets		3
Fixed Income Investments, Pooled Funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	543	545
Real estate and REITS
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	163	133
Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	182	181
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	788	434
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	79	77
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	207	195
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	90	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	200	162
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
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	212	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	0
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	262	190
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	62	22
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	167	128
Significant Other Observable Inputs (Level 2) | Government and agency bonds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets	33	37
Significant Other Observable Inputs (Level 2) | Asset-backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets		3
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
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