Borrowings and Other Financing Instruments Short-Term Debt (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]
Amount outstanding at period end	$ 813	$ 813	$ 1,005
Commercial Paper
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	3,550	3,550	3,100	$ 3,100
Amount outstanding at period end	813	813	1,005	584
Average amount outstanding	416	552	1,399	1,126
Maximum amount outstanding	$ 813	$ 1,357	$ 2,054	$ 2,080
Weighted average interest rate, computed on a daily basis (percentage)	4.20%	1.47%	0.57%	1.45%
Weighted average interest rate at period end (percentage)	4.66%	4.66%	0.31%	0.23%