Regulatory Matters - Four Corners and Cholla (Details) (APS, USD $) In Millions, unless otherwise specified	0 Months Ended		3 Months Ended
	Dec. 23, 2014	Dec. 30, 2013 MW	Mar. 31, 2015
SCE | Four Corners Units 4 and 5
Business Acquisition [Line Items]
Ownership interest acquired		48.00%
Settlement agreement, ACC approved rate adjustment, annualized customer impact	$ 57.1
Net receipt due to negotiation of alternate arrangement		40
Capacity rights over the Arizona Transmission System assign to third-parties		1,555
Capacity rights related to marketing and trading group for transmission of the additional power received assign to third-parties		300
Four Corners cost deferral | SCE | Four Corners Units 4 and 5
Business Acquisition [Line Items]
Regulatory assets, non-current			75
Regulatory noncurrent asset amortization period			10 years
Retired power plant costs
Business Acquisition [Line Items]
Net book value			$ 127