Borrowings and Other Financing Instruments, Short-Term Borrowings (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Short-term debt	$ 294	$ 294	$ 147
Letter of Credit
Short-term Debt [Line Items]
Line of Credit Facility, Expiration Period		1 year
Commercial Paper [Member]
Short-term Debt [Line Items]
Borrowing limit	700	$ 700	700	$ 700
Short-term debt	294	294	147	136
Average amount outstanding	$ 155	$ 71	$ 26	$ 30
Weighted average interest rate at period end (percentage)	4.73%	4.73%	0.22%	0.20%
Line of Credit Facility, Interest Rate During Period	4.24%	2.56%	0.19%	1.59%
Maximum amount outstanding	$ 294	$ 328	$ 322	$ 230
Money Pool
Short-term Debt [Line Items]
Borrowing limit	250	250	250	250
Short-term debt	0	0	0	57
Average amount outstanding	$ 21	$ 29	$ 12	$ 59
Weighted average interest rate at period end (percentage)				0.70%
Line of Credit Facility, Interest Rate During Period	3.12%	1.66%	0.07%	0.60%
Maximum amount outstanding	$ 165	$ 250	$ 243	$ 250