Borrowings and Other Financing Instruments - Money Pool (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Short-term Debt [Line Items]
Short-term debt	$ 0	$ 75
Money Pool
Short-term Debt [Line Items]
Borrowing limit	100	100
Short-term debt	0	27
Average amount outstanding	48	46
Maximum amount outstanding	$ 100	$ 100
Weighted average interest rate, computed on a daily basis	5.33%	5.04%
Weighted average interest rate at period end		5.34%
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	$ 500	$ 500
Short-term debt	0	75
Average amount outstanding	51	50
Maximum amount outstanding	$ 160	$ 119
Weighted average interest rate, computed on a daily basis	5.59%	5.12%
Weighted average interest rate at period end		5.56%