Borrowings and Other Financing Instruments, Credit Facilities (Details) - Revolving Credit Facility [Member] - USD ($) $ in Thousands		Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Credit Facility	[1]	$ 3,100,000
Outstanding	[2]	1,128,000
Available		1,972,000
Direct advances on the credit facility outstanding		0		$ 0
PSCo
Line of Credit Facility [Line Items]
Credit Facility	[1]	700,000
Outstanding	[2]	231,000
Available		469,000
NSP-Minnesota
Line of Credit Facility [Line Items]
Credit Facility	[1]	500,000
Outstanding	[2]	213,000
Available		287,000
SPS
Line of Credit Facility [Line Items]
Credit Facility	[1]	500,000	$ 400,000
Outstanding	[2]	2,000
Available		498,000
NSP-Wisconsin
Line of Credit Facility [Line Items]
Credit Facility	[1]	150,000
Outstanding	[2]	50,000
Available		100,000
Xcel Energy Inc.
Line of Credit Facility [Line Items]
Credit Facility	[1]	1,250,000	$ 1,000,000
Outstanding	[2]	632,000
Available		$ 618,000

[1] ^(a)  Expires in June 2024.

[2] ^(b)  Includes outstanding commercial paper and letters of credit.