Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at statutory rate									$ 113,828	$ 139,533	$ 268,177
State income tax net of federal income tax benefit									18,599	23,115	21,380
State income tax credits net of federal income tax benefit									(8,519)	(6,704)	(6,483)
Nondeductible expenditures associated with ballot initiative									0	7,879	0
Stock compensation									(2,252)	(1,804)	(6,659)
Excess deferred income taxes - Tax Cuts and Jobs Act									(124,082)	(6,725)	9,348
Allowance for equity funds used during construction (see Note 1)									(2,476)	(7,231)	(12,937)
Palo Verde VIE noncontrolling interest (see Note 19)									(4,094)	(4,094)	(6,823)
Investment tax credit amortization									(6,851)	(6,742)	(6,715)
Other									74	(3,325)	(1,016)
Income tax expense/(benefit)	$ (88,537)	$ 53,266	$ 17,080	$ 2,418	$ 6,795	$ 84,333	$ 44,039	$ (1,265)	(15,773)	133,902	258,272
ARIZONA PUBLIC SERVICE COMPANY
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at statutory rate									120,790	154,260	277,540
State income tax net of federal income tax benefit									19,267	24,531	22,329
State income tax credits net of federal income tax benefit									(6,781)	(5,440)	(5,053)
Nondeductible expenditures associated with ballot initiative									0	0	0
Stock compensation									(1,054)	(780)	(3,489)
Excess deferred income taxes - Tax Cuts and Jobs Act									(124,082)	(4,715)	9,431
Allowance for equity funds used during construction (see Note 1)									(2,476)	(7,231)	(12,937)
Palo Verde VIE noncontrolling interest (see Note 19)									(4,094)	(4,094)	(6,823)
Investment tax credit amortization									(6,851)	(6,742)	(6,715)
Other									(4,291)	(4,975)	(5,115)
Income tax expense/(benefit)									$ (9,572)	$ 144,814	$ 269,168