Pension Benefits - Schedule of Fair Value of Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	$ 459	$ 525
Defined benefit plan, funded (unfunded) status of plan related to private equity	$ 260
Private Equity
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List]	Fair Value Measured at Net Asset Value Per Share	Fair Value Measured at Net Asset Value Per Share
Private Equity | Minimum
Defined Benefit Plan Disclosure [Line Items]
Period of sale of limited partnership interests in secondary market (in years)	3 months
Private Equity | Maximum
Defined Benefit Plan Disclosure [Line Items]
Period of sale of limited partnership interests in secondary market (in years)	6 months
Real Estate and Other Alternatives
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List]	Fair Value Measured at Net Asset Value Per Share	Fair Value Measured at Net Asset Value Per Share
Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Fair Value by Hierarchy and NAV [Extensible List]	Fair Value Measured at Net Asset Value Per Share	Fair Value Measured at Net Asset Value Per Share
Period of liquidation (in years)	18 months
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	$ 14,979	$ 18,504	$ 17,022	$ 15,608
Pension Benefits | U.S. Equity
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	2,153	4,381
Pension Benefits | International Equity
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	1,534	3,536
Pension Benefits | U.S. Government Issued Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	823	1,500
Pension Benefits | Corporate Bonds Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	4,961	3,936
Pension Benefits | Structured Assets Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	183	262
Pension Benefits | Other Fixed Income Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	1,088	1,186
Pension Benefits | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	345	505
Pension Benefits | Futures
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	(1)	2
Pension Benefits | Private Equity
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	1,018	913
Pension Benefits | Real Estate and Other Alternatives
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	2,366	2,306
Pension Benefits | Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	657	315
Pension Benefits | Total Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	(190)	(258)
Pension Benefits | Pending Activities
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	42	(80)
Pension Benefits | Fair Value, Inputs, Level 1 and 2 | Total investments
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	11,086	15,308
Pension Benefits | Fair Value, Inputs, Level 1 and 2 | Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	(139)	(210)
Pension Benefits | Fair Value, Inputs, Level 1 and 2 | Investments Excluding Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	14,937	18,584
Pension Benefits | Level 1 | Total investments
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	3,754	7,999
Pension Benefits | Level 1 | U.S. Equity
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	2,150	4,381
Pension Benefits | Level 1 | International Equity
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	1,534	3,536
Pension Benefits | Level 1 | U.S. Government Issued Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Pension Benefits | Level 1 | Corporate Bonds Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Pension Benefits | Level 1 | Structured Assets Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Pension Benefits | Level 1 | Other Fixed Income Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	0	0
Pension Benefits | Level 1 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	71	80
Pension Benefits | Level 1 | Futures
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	(1)	2
Pension Benefits | Level 1 | Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	(48)	(110)
Pension Benefits | Level 1 | Investments Excluding Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	3,706	7,889
Pension Benefits | Level 2 | Total investments
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	7,332	7,309
Pension Benefits | Level 2 | U.S. Equity
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	3	0
Pension Benefits | Level 2 | U.S. Government Issued Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	823	1,500
Pension Benefits | Level 2 | Corporate Bonds Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	4,961	3,936
Pension Benefits | Level 2 | Structured Assets Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	183	262
Pension Benefits | Level 2 | Other Fixed Income Debt
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	1,088	1,186
Pension Benefits | Level 2 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	274	425
Pension Benefits | Level 2 | Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	(91)	(100)
Pension Benefits | Level 2 | Investments Excluding Funds For Retiree Health Benefits
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	7,241	7,209
Pension Benefits | Fair Value Measured at Net Asset Value Per Share | Investments Valued Using NAV Per Share
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	4,041	3,534
Pension Benefits | Fair Value Measured at Net Asset Value Per Share | Funds For Retiree Health Benefits Measured At Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Total fair value of plan net assets	$ (51)	$ (48)