Pension and Other Postretirement Benefits - Benefit Plan Assets by Category and Valuation Methodology (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 2,114	$ 3,041	$ 3,096
Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	44	43
Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,040	1,375
Pension | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	336	434	$ 402
Other Postretirement Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Postretirement Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Cash and equivalents | Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	44	47
Cash and equivalents | Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	44	43
Cash and equivalents | Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	4
Cash and equivalents | Pension | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income securities, government securities | Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	299	370
Fixed income securities, government securities | Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income securities, government securities | Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	299	370
Fixed income securities, government securities | Pension | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income securities, corporate debt securities | Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	737	996
Fixed income securities, corporate debt securities | Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income securities, corporate debt securities | Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	737	996
Fixed income securities, corporate debt securities | Pension | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income securities, investment contracts with insurance companies | Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
Fixed income securities, investment contracts with insurance companies | Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income securities, investment contracts with insurance companies | Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed income securities, investment contracts with insurance companies | Pension | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
Commingled funds, mutual funds | Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22	28
Commingled funds, mutual funds | Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Commingled funds, mutual funds | Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Commingled funds, mutual funds | Pension | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Commingled funds, collective trust funds | Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	994	1,573
Commingled funds, collective trust funds | Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Commingled funds, collective trust funds | Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Commingled funds, collective trust funds | Pension | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Commingled funds, partnerships/private equity interests | Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13	21
Commingled funds, partnerships/private equity interests | Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Commingled funds, partnerships/private equity interests | Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Commingled funds, partnerships/private equity interests | Pension | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Other | Pension
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	5
Other | Pension | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other | Pension | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	5
Other | Pension | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Life insurance policies | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	336	434
Life insurance policies | Other Postretirement Benefits | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Life insurance policies | Other Postretirement Benefits | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets
Life insurance policies | Other Postretirement Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets