Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at statutory rate									$ 139,533	$ 268,177	$ 244,278
State income tax net of federal income tax benefit									16,411	14,897	16,311
Nondeductible expenditures associated with ballot initiative									7,879	0	0
Stock compensation									(1,804)	(6,659)	(2,951)
Excess deferred income taxes - Tax Cuts and Jobs Act									(6,725)	9,348	0
Allowance for equity funds used during construction (see Note 1)									(7,231)	(12,937)	(11,724)
Palo Verde VIE noncontrolling interest (see Note 18)									(4,094)	(6,823)	(6,823)
Investment tax credit amortization									(6,742)	(6,715)	(5,887)
Other									(3,325)	(1,016)	3,207
Income tax expense	$ 6,795	$ 84,333	$ 44,039	$ (1,265)	$ 20,775	$ 144,319	$ 88,967	$ 4,211	133,902	258,272	236,411
ARIZONA PUBLIC SERVICE COMPANY
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at statutory rate									154,260	277,540	254,617
State income tax net of federal income tax benefit									19,091	17,276	18,750
Nondeductible expenditures associated with ballot initiative									0	0	0
Stock compensation									(780)	(3,489)	(1,937)
Excess deferred income taxes - Tax Cuts and Jobs Act									(4,715)	9,431	0
Allowance for equity funds used during construction (see Note 1)									(7,231)	(12,937)	(11,724)
Palo Verde VIE noncontrolling interest (see Note 18)									(4,094)	(6,823)	(6,823)
Investment tax credit amortization									(6,742)	(6,715)	(5,887)
Other									(4,975)	(5,115)	(1,154)
Income tax expense									$ 144,814	$ 269,168	$ 245,842