REGULATORY, General Rate Cases (Details) (GRC [Member], USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
SPPC Gas [Member]
Summary of General Rate Case [Line Items]
Anticipated Effective Date of Rate Filing	January 1, 2014
Requested Increase Decrease In General Rates	$ 10.2
Percentage Overall Increase Decrease In General Rates	11.40%
Requested Rate Of Return	7.72%
Requested Return On Equity	10.35%
General Rate Case Hearing Date	October 2013
SPPC Electric [Member]
Summary of General Rate Case [Line Items]
Anticipated Effective Date of Rate Filing	January 1, 2014
Requested Increase Decrease In General Rates	$ (9.4)
Percentage Overall Increase Decrease In General Rates	(1.40%)
Requested Rate Of Return	7.74%
Requested Return On Equity	10.40%
General Rate Case Hearing Date	October 2013