Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Taxes
Reduction in net deferred income tax liabilities	$ 1,140,000,000
Regulatory liabilities, non-current	2,452,536,000	$ 948,916,000
Income tax expense recognized for tax reform	9,300,000
Interest income to be received on the overpayment of income taxes for certain adjustments that we have filed, or will file, with the IRS (less than)	1,000,000
General business tax credit carryforwards that will begin to expire in 2031	79,000,000
Amount of federal and state loss carryforwards which will begin to expire in 2019	6,000,000
increase (decrease) in deferred income taxes due to regulation adoption	31,000,000
ARIZONA PUBLIC SERVICE COMPANY
Income Taxes
Reduction in net deferred income tax liabilities	1,140,000,000
Regulatory liabilities, non-current	2,452,536,000	948,916,000
Gross-up for revenue requirement of rate regulation	377,000,000
Palo Verde VIE
Income Taxes
Income tax expense benefit attributable to non controlling interests	0
Excess deferred income taxes - Tax Cuts and Jobs Act
Income Taxes
Regulatory liabilities, non-current	1,520,274,000	$ 0
Excess deferred income taxes - Tax Cuts and Jobs Act | ARIZONA PUBLIC SERVICE COMPANY
Income Taxes
Regulatory liabilities, non-current	$ 1,520,000,000