Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	$ 3	$ 10
Accounts payable	23	15
NSP-Minnesota
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	0	0
Accounts payable	13	6
PSCo
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	2	1
Accounts payable	0	0
Other subsidiaries of Xcel Energy Inc.
Accounts Receivable and Payable with Affiliates [Abstract]
Accounts receivable	1	9
Accounts payable	10	9
Purchased Power
Operating expenses
Costs and Expenses, Related Party	408	379	$ 394
Transmission Expense
Operating expenses
Costs and Expenses, Related Party	64	61	64
Natural Gas Purchase for Resale
Operating expenses
Costs and Expenses, Related Party	1	1	1
Other Expense
Operating expenses
Costs and Expenses, Related Party	99	92	87
Electricity, US Regulated
Operating revenues
Revenue from Related Parties	$ 189	$ 168	$ 177