Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Comparison of pretax income from continuing operations at the federal income tax rate to income tax expense - continuing operations
Federal income tax rate (as a percent)									35.00%	35.00%	35.00%
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at 35% statutory rate									$ 268,177	$ 244,278	$ 242,869
State income tax net of federal income tax benefit									14,897	16,311	18,265
Credits and favorable adjustments related to prior years resolved in current year									0	0	(2,169)
Medicare Subsidy Part-D									853	844	837
Stock compensation									(6,659)	(2,951)	0
Excess Deferred Income Taxes - Tax Cuts and Jobs Act									9,348	0	0
Allowance for equity funds used during construction (see Note 1)									(12,937)	(11,724)	(9,711)
Palo Verde VIE noncontrolling interest (see Note 18)									(6,823)	(6,823)	(6,626)
Investment tax credit amortization									(6,715)	(5,887)	(5,527)
Other									(1,869)	2,363	(218)
Income tax expense	$ 20,775	$ 144,319	$ 88,967	$ 4,211	$ 27,309	$ 141,446	$ 65,742	$ 1,914	$ 258,272	$ 236,411	$ 237,720
ARIZONA PUBLIC SERVICE COMPANY
Comparison of pretax income from continuing operations at the federal income tax rate to income tax expense - continuing operations
Federal income tax rate (as a percent)									35.00%	35.00%	35.00%
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at 35% statutory rate									$ 277,540	$ 254,617	$ 250,267
State income tax net of federal income tax benefit									17,276	18,750	20,433
Credits and favorable adjustments related to prior years resolved in current year									0	0	(1,892)
Medicare Subsidy Part-D									853	844	837
Stock compensation									(3,489)	(1,937)	0
Excess Deferred Income Taxes - Tax Cuts and Jobs Act									9,431	0	0
Allowance for equity funds used during construction (see Note 1)									(12,937)	(11,724)	(9,711)
Palo Verde VIE noncontrolling interest (see Note 18)									(6,823)	(6,823)	(6,626)
Investment tax credit amortization									(6,715)	(5,887)	(5,527)
Other									(5,968)	(1,998)	(1,940)
Income tax expense									$ 269,168	$ 245,842	$ 245,841