Fair Value Measurements - Schedule of Changes in Fair Value of the Level 3 Assets and Liabilities (Details) - Level 3 - Commodity Contract - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net liability balance at beginning of period	$ (752)	$ (1,044)
Total unrealized valuation (losses)	(243)	(269)
Purchases, issuances and settlements
Purchases	49	70
Issuances	(2)	(3)
Settlements	(7)	99
Transfers into Level 3	1	3
Transfers out of Level 3	10	8
Net liabilities assumed in connection with the Energy Harbor Merger	0	(13)
Net change	(192)	(105)
Net liability balance at end of period	(944)	(1,149)
Unrealized valuation (losses) relating to instruments held at end of period	$ (266)	$ (325)