Income Taxes - Summary of Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Tax positions, that if recognized, would decrease our effective tax rate	$ 16,373,000	$ 11,313,000	$ 9,523,000
Unrecognized tax benefit interest expense/(benefit) recognized	577,000	529,000	(161,000)
Unrecognized tax benefit interest accrued	1,910,000	1,333	804
ARIZONA PUBLIC SERVICE COMPANY
Income Tax [Line Items]
Tax positions, that if recognized, would decrease our effective tax rate	16,373,000	11,313,000	9,523,000
Unrecognized tax benefit interest expense/(benefit) recognized	577,000	529,000	(161,000)
Unrecognized tax benefit interest accrued	$ 1,910	$ 1,333	$ 804