Borrowings and Other Financing Instruments, Credit Facilities (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013
Credit Facilities [Abstract]
Credit facility	$ 2,450,000,000	[1]
Drawn	811,400,000	[2]
Available	1,638,600,000
Credit facility bank borrowings outstanding	0		0
Xcel Energy Inc.
Credit Facilities [Abstract]
Credit facility	800,000,000	[1]
Drawn	487,000,000	[2]
Available	313,000,000
PSCo
Credit Facilities [Abstract]
Credit facility	700,000,000	[1]
Drawn	6,500,000	[2]
Available	693,500,000
NSP-Minnesota
Credit Facilities [Abstract]
Credit facility	500,000,000	[1]
Drawn	148,900,000	[2]
Available	351,100,000
SPS
Credit Facilities [Abstract]
Credit facility	300,000,000	[1]
Drawn	90,000,000	[2]
Available	210,000,000
NSP-Wisconsin
Credit Facilities [Abstract]
Credit facility	150,000,000	[1]
Drawn	79,000,000	[2]
Available	$ 71,000,000

[1] These credit facilities expire in July 2017.

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