Borrowings and Other Financing Instruments Credit Facilities (Details) - Revolving Credit Facility [Member]		12 Months Ended
		Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 3,100,000,000
Parent [Member]
Line of Credit Facility [Line Items]
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Line Of Credit Facility Minimum Threshhold Percentage Of Subsidiary Assets To Consolidated Assets Required To Initiate Cross Default Provisions		15.00%
Line of Credit Facility, Minimum Amount of Indebtedness in Default to Initiate Cross Default Provisions		$ 75,000,000
Line of Credit Facility, Maximum Borrowing Capacity	[1]	3,100,000,000
Drawn	[2]	116,000,000
Available		$ 2,984,000,000
Xcel Energy Inc.
Line of Credit Facility [Line Items]
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)	[3],[4]	58.00%	58.00%
Line Of Credit Facility Maximum Amount Credit Facility May Be Increased	[4]	$ 200,000,000
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval	[4],[5]	2
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Line Of Credit Facility Minimum Threshhold Percentage Of Subsidiary Assets To Consolidated Assets Required To Initiate Cross Default Provisions		15.00%
Line of Credit Facility, Minimum Amount of Indebtedness in Default to Initiate Cross Default Provisions		$ 75,000,000
Line of Credit Facility, Maximum Borrowing Capacity	[1]	1,250,000,000
Drawn	[2]	0
Available		$ 1,250,000,000
Direct advances on the credit facility outstanding			$ 0
NSP-Wisconsin
Line of Credit Facility [Line Items]
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)	[3]	48.00%	48.00%
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval	[5]	1
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Line of Credit Facility, Maximum Borrowing Capacity	[1]	$ 150,000,000
Drawn	[2]	65,000,000
Available		85,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0
NSP Minnesota
Line of Credit Facility [Line Items]
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)	[3]	48.00%	48.00%
Line Of Credit Facility Maximum Amount Credit Facility May Be Increased		$ 100,000,000
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval	[5]	2
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Line Of Credit Facility Minimum Threshhold Percentage Of Subsidiary Assets To Consolidated Assets Required To Initiate Cross Default Provisions		15.00%
Line of Credit Facility, Minimum Amount of Indebtedness in Default to Initiate Cross Default Provisions		$ 75,000,000
Line of Credit Facility, Maximum Borrowing Capacity	[1]	500,000,000
Drawn	[2]	2,000,000
Available		498,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0
SPS
Line of Credit Facility [Line Items]
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)	[3]	46.00%	46.00%
Line Of Credit Facility Maximum Amount Credit Facility May Be Increased		$ 50,000,000
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval	[5]	2
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Line Of Credit Facility Minimum Threshhold Percentage Of Subsidiary Assets To Consolidated Assets Required To Initiate Cross Default Provisions		15.00%
Line of Credit Facility, Minimum Amount of Indebtedness in Default to Initiate Cross Default Provisions		$ 75,000,000
Line of Credit Facility, Maximum Borrowing Capacity	[1]	500,000,000
Drawn	[2]	40,000,000
Available		460,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0
PSCo
Line of Credit Facility [Line Items]
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)	[3]	44.00%	46.00%
Line Of Credit Facility Maximum Amount Credit Facility May Be Increased		$ 100,000,000
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval	[5]	2
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Line Of Credit Facility Minimum Threshhold Percentage Of Subsidiary Assets To Consolidated Assets Required To Initiate Cross Default Provisions		15.00%
Line of Credit Facility, Minimum Amount of Indebtedness in Default to Initiate Cross Default Provisions		$ 75,000,000
Line of Credit Facility, Maximum Borrowing Capacity	[1]	700,000,000
Drawn	[2]	9,000,000
Available		691,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0

[1] These credit facilities mature in June 2024.

[2] Includes outstanding commercial paper and letters of credit.

[3] Each credit facility has a financial covenant requiring that the debt-to-total capitalization ratio be less than or equal to 65%.

[4] The Xcel Energy Inc. credit facility has a cross-default provision that Xcel Energy Inc. will be in default on its borrowings under the facility if it or any of its subsidiaries (except NSP-Wisconsin as long as its total assets do not comprise more than 15% of Xcel Energy’s consolidated total assets) default on indebtedness in an aggregate principal amount exceeding $75 million.

[5] All extension requests are subject to majority bank group approval.