Income Taxes - Summary of Significant Factors Impact on Difference Between Effective Tax Rate and Federal Statutory Rate (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Federal income taxes at statutory rates	$ 19	$ 15
Flow through related to deduction of meters and mixed service costs	(3)	(9)
Tax effect of regulatory treatment of utility plant differences	(5)	(5)
State income tax expense	1	1
Total income tax expense	$ 12	$ 2
Federal income taxes at statutory rates	21.00%	21.00%
Flow through related to deduction of meters and mixed service costs	(3.30%)	(12.20%)
Tax effect of regulatory treatment of utility plant differences	(5.50%)	(6.40%)
State income tax expense	1.00%	0.70%
Total income tax expense	13.20%	3.10%