Retirement Benefits Categorization of Plan Assets (Details 7) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	$ 31,525	$ 30,146
Cash and cash equivalents
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	915	1,191
U.S. equities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	1,713	2,139
International equities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	1,506	1,784
U.S. Treasuries
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	3,890	2,999
U.S. Government Agency
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	124	145
Non-U.S. Government
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	176	172
Corporate debt
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	4,506	4,745
Asset backed
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	436	353
High yield debt
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	33	31
Bank loans
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	15	13
Other assets
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	109	4
Notes Payable, Other Payables [Member]
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	(24)	(25)
Level 1
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	3,454	4,099
Level 1 | Cash and cash equivalents
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	85	115
Level 1 | U.S. equities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	1,712	2,138
Level 1 | International equities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	1,506	1,784
Level 1 | U.S. Treasuries
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	0	22
Level 1 | Corporate debt
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	74	28
Level 1 | High yield debt
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	13	12
Level 1 | Other assets
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	64
Level 2
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	9,967	9,475
Level 2 | Cash and cash equivalents
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	830	1,076
Level 2 | U.S. equities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	1	1
Level 2 | U.S. Treasuries
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	3,890	2,977
Level 2 | U.S. Government Agency
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	124	145
Level 2 | Non-U.S. Government
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	176	172
Level 2 | Corporate debt
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	4,432	4,717
Level 2 | Asset backed
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	436	353
Level 2 | High yield debt
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	20	19
Level 2 | Bank loans
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	15	13
Level 2 | Other assets
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	43	2
Level 3
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	2	2
Level 3 | Other assets
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	2	2
Fair Value Measured at Net Asset Value Per Share | U.S. equities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	1,294	1,043
Fair Value Measured at Net Asset Value Per Share | International equities
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	3,972	3,904
Fair Value Measured at Net Asset Value Per Share | Fixed Income Funds
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	4,057	2,569
Fair Value Measured at Net Asset Value Per Share | Hedge Funds
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	38	44
Fair Value Measured at Net Asset Value Per Share | OpportunisticFunds
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	3,176	2,983
Fair Value Measured at Net Asset Value Per Share | Private Equity Funds [Member]
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	3,466	3,299
Fair Value Measured at Net Asset Value Per Share | Real Estate Funds [Member]
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Fair value of plan assets	2,123	2,753
Pension and Other Post-retirement benefit plans [Member]
Plan Assets by Fair Value Measurement Input (Table Amounts) [Abstract]
Derivative Asset	172	71
Derivative Liability	(101)	(117)
Derivative, Notional Amount	$ 4,900	$ 3,200