Fair Value Measurement - Fair Value Measurement Inputs (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Investment securities (current and long-term):
Other Assets, Current	$ 406	$ 381
Other assets	1,709	1,601
Derivatives:
Derivative Asset	13	170
Derivatives: [Abstract]
Derivative Liability	41	42
Fair Value Measured at Net Asset Value Per Share
Investment securities (current and long-term):
Investments, Fair Value Disclosure	25	25
Trust Assets Fair Value Disclosure	61	56
Derivatives:
Derivative Asset		0
Discontinued Operation, Contingent Receivable	0	0
Derivatives: [Abstract]
Derivative Liability	0	0
Long-term debt, including current portion	0	0
Level 1
Investment securities (current and long-term):
Investments, Fair Value Disclosure	5	7
Trust Assets Fair Value Disclosure	19	3
Derivatives:
Derivative Asset		4
Discontinued Operation, Contingent Receivable	0	0
Derivatives: [Abstract]
Derivative Liability	7	0
Long-term debt, including current portion	0	0
Level 2
Investment securities (current and long-term):
Investments, Fair Value Disclosure	0	0
Trust Assets Fair Value Disclosure	119	122
Derivatives:
Derivative Asset		166
Discontinued Operation, Contingent Receivable	0	0
Derivatives: [Abstract]
Derivative Liability	37	42
Long-term debt, including current portion	8,639	10,097
Level 3
Investment securities (current and long-term):
Investments, Fair Value Disclosure	0	0
Trust Assets Fair Value Disclosure	0	0
Derivatives:
Derivative Asset		0
Discontinued Operation, Contingent Receivable	47	57
Derivatives: [Abstract]
Derivative Liability	0	0
Long-term debt, including current portion	0	0
Estimate of Fair Value Measurement
Investment securities (current and long-term):
Investments, Fair Value Disclosure	30	32
Trust Assets Fair Value Disclosure	199	181
Derivatives:
Derivative Asset		170
Discontinued Operation, Contingent Receivable	47	57
Derivatives: [Abstract]
Derivative Liability	44	42
Long-term debt, including current portion	8,639	10,097
Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Investments, Fair Value Disclosure	30	32
Trust Assets Fair Value Disclosure	199	181
Derivatives:
Derivative Asset		170
Discontinued Operation, Contingent Receivable	55	67
Derivatives: [Abstract]
Derivative Liability	44	42
Long-term debt, including current portion	9,405	10,620
Embedded Derivative Financial Instruments
Derivatives:
Derivative Asset	13	166
Derivatives: [Abstract]
Derivative Liability	32	39
Embedded Derivative Financial Instruments | Fair Value Measured at Net Asset Value Per Share
Derivatives:
Derivative Asset	0	0
Derivatives: [Abstract]
Derivative Liability	0	0
Embedded Derivative Financial Instruments | Level 1
Derivatives:
Derivative Asset	0	0
Derivatives: [Abstract]
Derivative Liability	0	0
Embedded Derivative Financial Instruments | Level 2
Derivatives:
Derivative Asset	16	166
Derivatives: [Abstract]
Derivative Liability	35	39
Embedded Derivative Financial Instruments | Level 3
Derivatives:
Derivative Asset	0	0
Derivatives: [Abstract]
Derivative Liability	0	0
Embedded Derivative Financial Instruments | Estimate of Fair Value Measurement
Derivatives:
Derivative Asset	16	166
Derivatives: [Abstract]
Derivative Liability	35	39
Embedded Derivative Financial Instruments | Carrying Amount, Fair Value Disclosure
Derivatives:
Derivative Asset	16	166
Derivatives: [Abstract]
Derivative Liability	35	39
Forward Contracts | Level 1
Derivatives:
Derivative Asset		1
Forward Contracts | Level 2
Derivatives:
Derivative Asset		0
Forward Contracts | Level 3
Derivatives:
Derivative Asset		0
Forward Contracts | Estimate of Fair Value Measurement
Derivatives:
Derivative Asset		1
Forward Contracts | Carrying Amount, Fair Value Disclosure
Derivatives:
Derivative Asset		1
Commodity Contract
Derivatives:
Derivative Asset	0	4
Derivatives: [Abstract]
Derivative Liability	9	3
Commodity Contract | Fair Value Measured at Net Asset Value Per Share
Derivatives:
Derivative Asset		0
Derivatives: [Abstract]
Derivative Liability		0
Commodity Contract | Fair Value Measured at Net Asset Value Per Share | Forward Contracts
Derivatives: [Abstract]
Derivative Liability	0
Commodity Contract | Fair Value Measured at Net Asset Value Per Share | Futures and Swaps
Derivatives: [Abstract]
Derivative Liability	0
Commodity Contract | Level 1
Derivatives:
Derivative Asset		3
Derivatives: [Abstract]
Derivative Liability		0
Commodity Contract | Level 1 | Forward Contracts
Derivatives: [Abstract]
Derivative Liability	1
Commodity Contract | Level 1 | Futures and Swaps
Derivatives: [Abstract]
Derivative Liability	6
Commodity Contract | Level 2
Derivatives:
Derivative Asset		0
Derivatives: [Abstract]
Derivative Liability		3
Commodity Contract | Level 2 | Forward Contracts
Derivatives: [Abstract]
Derivative Liability	0
Commodity Contract | Level 2 | Futures and Swaps
Derivatives: [Abstract]
Derivative Liability	2
Commodity Contract | Level 3
Derivatives:
Derivative Asset		0
Derivatives: [Abstract]
Derivative Liability		0
Commodity Contract | Level 3 | Forward Contracts
Derivatives: [Abstract]
Derivative Liability	0
Commodity Contract | Level 3 | Futures and Swaps
Derivatives: [Abstract]
Derivative Liability	0
Commodity Contract | Estimate of Fair Value Measurement
Derivatives:
Derivative Asset		3
Derivatives: [Abstract]
Derivative Liability		3
Commodity Contract | Estimate of Fair Value Measurement | Forward Contracts
Derivatives: [Abstract]
Derivative Liability	1
Commodity Contract | Estimate of Fair Value Measurement | Futures and Swaps
Derivatives: [Abstract]
Derivative Liability	8
Commodity Contract | Carrying Amount, Fair Value Disclosure
Derivatives:
Derivative Asset		3
Derivatives: [Abstract]
Derivative Liability		3
Commodity Contract | Carrying Amount, Fair Value Disclosure | Forward Contracts
Derivatives: [Abstract]
Derivative Liability	1
Commodity Contract | Carrying Amount, Fair Value Disclosure | Futures and Swaps
Derivatives: [Abstract]
Derivative Liability	8
U.S. core fixed income fund | Fair Value Measured at Net Asset Value Per Share
Investment securities (current and long-term):
Marketable Securities	25	25
Trust Assets Fair Value Disclosure	61	56
U.S. core fixed income fund | Level 1
Investment securities (current and long-term):
Marketable Securities	0	0
Trust Assets Fair Value Disclosure	0	0
U.S. core fixed income fund | Level 2
Investment securities (current and long-term):
Marketable Securities	0	0
Trust Assets Fair Value Disclosure	0	0
U.S. core fixed income fund | Level 3
Investment securities (current and long-term):
Marketable Securities	0	0
Trust Assets Fair Value Disclosure	0	0
U.S. core fixed income fund | Estimate of Fair Value Measurement
Investment securities (current and long-term):
Marketable Securities	25	25
Trust Assets Fair Value Disclosure	61	56
U.S. core fixed income fund | Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Marketable Securities	25	25
Trust Assets Fair Value Disclosure	61	56
Equity securities | Fair Value Measured at Net Asset Value Per Share
Investment securities (current and long-term):
Marketable Securities	0	0
Equity securities | Level 1
Investment securities (current and long-term):
Marketable Securities	5	7
Equity securities | Level 2
Investment securities (current and long-term):
Marketable Securities	0	0
Equity securities | Level 3
Investment securities (current and long-term):
Marketable Securities	0	0
Equity securities | Estimate of Fair Value Measurement
Investment securities (current and long-term):
Marketable Securities	5	7
Equity securities | Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Marketable Securities	5	7
Government mortgage-backed securities | Fair Value Measured at Net Asset Value Per Share
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government mortgage-backed securities | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government mortgage-backed securities | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	43	37
Government mortgage-backed securities | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government mortgage-backed securities | Estimate of Fair Value Measurement
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	43	37
Government mortgage-backed securities | Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	43	37
Government bonds | Fair Value Measured at Net Asset Value Per Share
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government bonds | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government bonds | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	30	34
Government bonds | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Government bonds | Estimate of Fair Value Measurement
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	30	34
Government bonds | Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	30	34
Corporate bonds | Fair Value Measured at Net Asset Value Per Share
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Corporate bonds | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Corporate bonds | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	30	31
Corporate bonds | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Corporate bonds | Estimate of Fair Value Measurement
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	30	31
Corporate bonds | Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	30	31
Money market funds | Fair Value Measured at Net Asset Value Per Share
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Money market funds | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	19	3
Money market funds | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Money market funds | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Money market funds | Estimate of Fair Value Measurement
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	19	3
Money market funds | Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	19	3
Asset-backed securities | Fair Value Measured at Net Asset Value Per Share
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Asset-backed securities | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Asset-backed securities | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	15	17
Asset-backed securities | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Asset-backed securities | Estimate of Fair Value Measurement
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	15	17
Asset-backed securities | Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	15	17
Collateralized Mortgage Backed Securities | Fair Value Measured at Net Asset Value Per Share
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Collateralized Mortgage Backed Securities | Level 1
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Collateralized Mortgage Backed Securities | Level 2
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	1	3
Collateralized Mortgage Backed Securities | Level 3
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	0	0
Collateralized Mortgage Backed Securities | Estimate of Fair Value Measurement
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	1	3
Collateralized Mortgage Backed Securities | Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Trust Assets Fair Value Disclosure	1	3
Bank Time Deposits | Carrying Amount, Fair Value Disclosure
Investment securities (current and long-term):
Other Assets, Current	111	103
Other assets	$ 135	133
Fair Value, Recurring [Member] | Forward Contracts | Estimate of Fair Value Measurement
Derivatives:
Derivative Asset		$ 0