Fair Value Measurements - Schedule of Changes in Fair Value of the Level 3 Assets and Liabilities (Details) - Level 3 - Commodity Contracts - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net liability balance at beginning of period	$ (944)	$ (1,149)	$ (752)	$ (1,044)
Total unrealized valuation gains (losses)	99	(19)	(144)	(288)
Purchases, issuances and settlements
Purchases	83	61	132	131
Issuances	(4)	(14)	(6)	(17)
Settlements	(84)	40	(91)	139
Transfers into Level 3	(6)	(23)	(5)	(20)
Transfers out of Level 3	(28)	0	(18)	8
Net liabilities assumed in connection with the Energy Harbor Merger	0	0	0	(13)
Net change	60	45	(132)	(60)
Net liability balance at end of period	(884)	(1,104)	(884)	(1,104)
Unrealized valuation losses relating to instruments held at end of period	$ (27)	$ (20)	$ (286)	$ (558)