Borrowings and Other Financing Instruments, Credit Facilities (Details) - Credit Facilities - USD ($)		3 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Credit Facility	[1]	$ 2,750,000,000
Drawn	[2]	621,000,000
Available		2,129,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0
Xcel Energy Inc.
Line of Credit Facility [Line Items]
Maturity Date		Jun. 30, 2021
Credit Facility	[1]	$ 1,000,000,000
Drawn	[2]	391,000,000
Available		609,000,000
PSCo
Line of Credit Facility [Line Items]
Credit Facility	[1]	700,000,000
Drawn	[2]	34,000,000
Available		666,000,000
NSP-Minnesota
Line of Credit Facility [Line Items]
Credit Facility	[1]	500,000,000
Drawn	[2]	47,000,000
Available		453,000,000
SPS
Line of Credit Facility [Line Items]
Credit Facility	[1]	400,000,000
Drawn	[2]	116,000,000
Available		284,000,000
NSP-Wisconsin
Line of Credit Facility [Line Items]
Credit Facility	[1]	150,000,000
Drawn	[2]	33,000,000
Available		$ 117,000,000

[1] These credit facilities mature in June 2021.

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