Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating expenses
Other receivables	$ 0	$ 19
Accounts payable to affiliates	21	19
NSP-Minnesota
Operating expenses
Other receivables	0	0
Accounts payable to affiliates	9	4
PSCo
Operating expenses
Other receivables	1	2
Accounts payable to affiliates	0	0
Other subsidiaries of Xcel Energy Inc.
Operating expenses
Other receivables	12	6
Accounts payable to affiliates	13	15
Xcel Energy [Member]
Operating expenses
Other receivables	13	8
Accounts payable to affiliates	22	19
Purchased Power
Operating expenses
Costs and Expenses, Related Party	424	445	$ 408
Transmission Expense
Operating expenses
Costs and Expenses, Related Party	69	68	64
Natural Gas Purchase for Resale
Operating expenses
Costs and Expenses, Related Party	1	0	1
Other Expense
Operating expenses
Costs and Expenses, Related Party	119	114	99
Interest Expense
Operating expenses
Costs and Expenses, Related Party	1	1	0
Electricity, US Regulated | Xcel Energy [Member]
Operating expenses
Revenues	204	202	189
Interest and Other Income	$ 1	$ 0	$ 0