Derivatives and Other Financial Instruments - Schedule of Fair Values of Level 3 Derivative Instruments Recorded as Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Derivative Instruments Gain Loss [Line Items]
Derivative Assets Current	$ 29	$ 134
Derivative Liabilities Current	214	200
Derivative Liabilities Noncurrent	1,092	1,026
Level 3 [Member] | Energy Contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Assets	16	52
Liabilities	1,297	1,212
Level 3 [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Energy Contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Assets	16	32
Level 3 [Member] | Derivatives Not Designated as Hedging Instruments [Member] | Financial Contracts [Member] | Energy Contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Assets Current	16	32
Level 3 [Member] | Derivatives Designated as Hedging Instruments [Member] | Energy Contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Assets	0	20
Liabilities	1,297	1,212
Level 3 [Member] | Derivatives Designated as Hedging Instruments [Member] | Financial Contracts [Member] | Energy Contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Assets Current	0	20
Level 3 [Member] | Derivatives Designated as Hedging Instruments [Member] | Power Contract [Member] | Energy Contracts [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Liabilities Current	210	195
Derivative Liabilities Noncurrent	$ 1,087	$ 1,017