Borrowings and Other Financing Instruments Term Loan Agreement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Amount outstanding at period end	$ 595	$ 1,038
Xcel Energy Inc.
Short-term Debt [Line Items]
Amount outstanding at period end	500	$ 488
Xcel Energy Inc. | 364-Day Term Loan
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	500
Amount outstanding at period end	500
Line of Credit Facility, Remaining Borrowing Capacity	0
Parent [Member] | Short-term Debt [Member] | 364-Day Term Loan
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 500
Line of Credit Facility, Expiration Period	364 days