Regulatory Matters - Deferred Fuel and Purchased Power Regulatory Asset (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in regulatory asset
Deferred fuel and purchased power costs — current period	$ 82,481	$ 78,277	$ 48,405
Amounts charged to customers	(49,508)	(116,750)	14,767
ARIZONA PUBLIC SERVICE COMPANY
Change in regulatory asset
Deferred fuel and purchased power costs — current period	82,481	78,277	48,405
Amounts charged to customers	(49,508)	(116,750)	14,767
ACC | ARIZONA PUBLIC SERVICE COMPANY | Power Supply Adjustor (PSA)
Change in regulatory asset
Beginning balance	37,164	75,637
Deferred fuel and purchased power costs — current period	82,481	78,277
Amounts charged to customers	(49,508)	(116,750)
Ending balance	$ 70,137	$ 37,164	$ 75,637