Pension - Summary of NAV and Fair Values of U.S. Pension Plans Assets by Asset Category (Details) - Pension Plan - U.S. Plans - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018	[1]	Dec. 31, 2017	[1]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 340	$ 331	[1]	$ 274		$ 279
Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	6	4
Equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	105	100
Investment Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	14	15
U.S. Treasury Obligations
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	16	132
Government Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	41	32
Corporate Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	126	16
Real Estate / Property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	32	32
NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	335	327
NAV | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	1
NAV | Equity
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	105	100
NAV | Investment Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	14	15
NAV | U.S. Treasury Obligations
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	16	132
NAV | Government Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	41	32
NAV | Corporate Bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	126	16
NAV | Real Estate / Property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	32	32
Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	5	4
Fair Value, Inputs, Level 1 | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plan assets	$ 5	$ 4

[1] 2018 "Beginning of year" is the Spin-Off date, October 29, 2018.