Borrowings and Other Financing Instruments, Credit Facilities (Details) - Credit Facilities		12 Months Ended
		Dec. 31, 2016 USD ($) Period	Dec. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Credit facility	[1]	$ 2,750,000,000
Drawn	[2]	411,000,000
Available		$ 2,339,000,000
Xcel Energy Inc.
Line of Credit Facility [Line Items]
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)		57.00%	57.00%
Credit facility	[1]	$ 1,000,000,000
Drawn	[2]	68,000,000
Available		932,000,000
Direct advances on the credit facility outstanding		0	$ 0
Line Of Credit Facility Maximum Amount Credit Facility May Be Increased		$ 200,000,000
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
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval | Period		2
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year
PSCo
Line of Credit Facility [Line Items]
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)		45.00%	45.00%
Credit facility	[1]	$ 700,000,000
Drawn	[2]	132,000,000
Available		568,000,000
Direct advances on the credit facility outstanding		0	$ 0
Line Of Credit Facility Maximum Amount Credit Facility May Be Increased		$ 100,000,000
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		2
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year
NSP-Minnesota
Line of Credit Facility [Line Items]
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)		48.00%	48.00%
Credit facility	[1]	$ 500,000,000
Drawn	[2]	96,000,000
Available		404,000,000
Direct advances on the credit facility outstanding		0	$ 0
Line Of Credit Facility Maximum Amount Credit Facility May Be Increased		$ 100,000,000
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		2
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year
SPS
Line of Credit Facility [Line Items]
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)		47.00%	46.00%
Credit facility	[1]	$ 400,000,000
Drawn	[2]	55,000,000
Available		345,000,000
Direct advances on the credit facility outstanding		0	$ 0
Line Of Credit Facility Maximum Amount Credit Facility May Be Increased		$ 50,000,000
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		2
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year
NSP-Wisconsin
Line of Credit Facility [Line Items]
Line Of Credit Facility Debt To Total Capitalization Ratio (as a percent)		47.00%	46.00%
Credit facility	[1]	$ 150,000,000
Drawn	[2]	60,000,000
Available		90,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0
Line Of Credit Facility Maximum Debt To Total Capitalization Ratio Allowed		65.00%
Number Of Additional Periods Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1
Term Of Each Additional Period Revolving Termination Date Can Be Extended Subject To Majority Bank Group Approval		1 year

[1] These credit facilities mature in June 2021.

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