Income Taxes - Summary of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Deferred tax liabilities:
Attributable to investment in OTA	$ 485	$ 462
Attributable to property, plant and equipment	137	151
Attributable to investments in other entities	4	5
Other	97	98
Total deferred tax liabilities	723	716
Deferred tax assets:
Net operating loss carryovers	65	56
Temporary differences related to Texas Margin Tax	3	4
Total deferred tax assets	68	60
Total net deferred tax liabilities	$ 655	$ 656