Borrowings and Other Financing Instruments, Credit Facilities (Details) (USD $)	Jun. 30, 2014		Dec. 31, 2013
Credit Facilities [Abstract]
Credit facility	$ 2,450,000,000	[1]
Drawn	849,200,000	[2]
Available	1,600,800,000
Credit facility bank borrowings outstanding	0		0
Xcel Energy Inc.
Credit Facilities [Abstract]
Credit facility	800,000,000	[1]
Drawn	384,000,000	[2]
Available	416,000,000
PSCo
Credit Facilities [Abstract]
Credit facility	700,000,000	[1]
Drawn	263,300,000	[2]
Available	436,700,000
NSP-Minnesota
Credit Facilities [Abstract]
Credit facility	500,000,000	[1]
Drawn	50,900,000	[2]
Available	449,100,000
SPS
Credit Facilities [Abstract]
Credit facility	300,000,000	[1]
Drawn	140,000,000	[2]
Available	160,000,000
NSP-Wisconsin
Credit Facilities [Abstract]
Credit facility	150,000,000	[1]
Drawn	11,000,000	[2]
Available	$ 139,000,000

[1] These credit facilities expire in July 2017.

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