Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at statutory rate	$ 136,127	$ 113,828	$ 139,533
State income tax net of federal income tax benefit	19,146	18,599	23,115
State income tax credits net of federal income tax benefit	(8,951)	(8,519)	(6,704)
Nondeductible expenditures associated with ballot initiative	0	0	7,879
Stock compensation	34	(2,252)	(1,804)
Excess deferred income taxes — Tax Cuts and Jobs Act	(50,543)	(124,082)	(6,725)
Allowance for equity funds used during construction (see Note 1)	(2,747)	(2,476)	(7,231)
Palo Verde VIE noncontrolling interest (see Note 18)	(4,094)	(4,094)	(4,094)
Investment tax credit amortization	(7,510)	(6,851)	(6,742)
Other	(3,289)	74	(3,325)
Income tax expense/(benefit)	78,173	(15,773)	133,902
ARIZONA PUBLIC SERVICE COMPANY
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at statutory rate	142,020	120,790	154,260
State income tax net of federal income tax benefit	20,124	19,267	24,531
State income tax credits net of federal income tax benefit	(7,213)	(6,781)	(5,440)
Nondeductible expenditures associated with ballot initiative	0	0	0
Stock compensation	183	(1,054)	(780)
Excess deferred income taxes — Tax Cuts and Jobs Act	(50,543)	(124,082)	(4,715)
Allowance for equity funds used during construction (see Note 1)	(2,747)	(2,476)	(7,231)
Palo Verde VIE noncontrolling interest (see Note 18)	(4,094)	(4,094)	(4,094)
Investment tax credit amortization	(7,510)	(6,851)	(6,742)
Other	(1,456)	(4,291)	(4,975)
Income tax expense/(benefit)	$ 88,764	$ (9,572)	$ 144,814