Income Taxes - Schedule of Reconciliation of Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Pre-Tax Net Book Income (“NBI”)	$ 1,343	$ 1,451	$ 4,243	$ 4,392
Texas Margin Tax	18	(13)	(12)	(40)
State income tax provision, net of federal benefit	0	(1)	(1)	(1)
Federal income tax provision computed by applying the federal statutory rate to NBI of corporate entities	(5)	(4)	(14)	(12)
Other	0	(1)	0	(2)
Total benefit from (provision for) income taxes	$ 13	$ (19)	$ (27)	$ (55)
Effective income tax rate	1.00%	(1.30%)	(0.60%)	(1.30%)