Income Taxes, Reconciliation (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024
Reconciliation of the provision for income taxes [Abstract]
Pre-Tax Net Book Income ("NBI")		$ 1,430	$ 1,504
Texas Margin Tax	[1]	(19)	(17)
State income tax provision, net of federal benefit		(1)	0
Federal income tax provision computed by applying the federal statutory rate to NBI of corporate entities		(4)	(3)
Other		0	(1)
Total provision for income taxes		$ (24)	$ (21)
Effective income tax rate		(1.70%)	(1.40%)

[1] Although the Texas Margin Tax is not considered a state income tax, it has the characteristics of an income tax since it is determined by applying a tax rate to a base that considers our Texas-sourced revenues and expenses.