Regulatory Matters - Four Corners (Details) (USD $)					0 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 APS	Dec. 31, 2013 APS	Dec. 30, 2013 APS SCE Four Corners Units 4 and 5 MW	Sep. 30, 2014 APS SCE Four Corners Units 4 and 5	Dec. 30, 2013 APS SCE Four Corners Units 4 and 5	Sep. 30, 2014 Four Corners cost deferral	Dec. 31, 2013 Four Corners cost deferral
Business Acquisition [Line Items]
Ownership interest acquired						48.00%	48.00%
Percentage of possible impact on average bill to residential customers					2.00%
Regulatory assets (Note 3)	$ 836,618,000	$ 711,712,000	$ 836,618,000	$ 711,712,000				$ 67,000,000	$ 37,000,000
Net receipt due to negotiation of alternate arrangement					$ 40,000,000
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