Pension Plans and Other Postretirement Benefit Plans - Additional Information (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
		Apr. 30, 2024	Dec. 31, 2024		Dec. 31, 2023		Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Payment for pension benefits			$ 10		$ 10		$ 42
Settlement loss							$ 12
Curtailment associated gain (loss)		$ 1
Percentage of service related net periodic benefit costs capitalized to utility property			45.00%
Percentage of service related net periodic benefit costs recorded to operating expenses			55.00%
Partial Settlement of Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory asset amortization period							12 years
Deferred Compensation, Excluding Share-based Payments and Retirement Benefits [Member] | Executive Officer [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation, earlier of retirement, termination, disability or death, percent			75.00%
Deferred compensation incentive payments, percent			100.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation			55.00%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation			40.00%
Real estate
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation			5.00%
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions to pension plan			$ 10
Settlement loss	[1]						$ 12
Regulatory asset amortization period							12 years
Curtailment associated gain (loss)			(1)
Fair value of plan assets			608	[2]	590	[2]	$ 541
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected contributions to pension plan			7
Fair value of plan assets			$ 67	[2]	$ 58	[2]	$ 49
Other Postretirement Benefits [Member] | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation			60.00%		60.00%
Other Postretirement Benefits [Member] | Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocation			40.00%		40.00%
Other Postretirement Benefits [Member] | Balanced Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets			$ 67		$ 58

[1] The settlement loss was deferred as a regulatory asset and is being amortized over 12 years in accordance with regulatory accounting orders. Pension costs other than service costs are presented in the Consolidated Statements of Income in the line item "Other income-net."

[2] As of December 31, 2024, the SERP had a projected benefit obligation of $27 million and an accumulated benefit obligation of $26 million, with no plan assets.