SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CONDENSED FINANCIAL STATEMENTS
Operating expenses	$ 2,798,830	$ 2,799,249	$ 2,917,560
Other
Total	89,044	86,803	109,040
Interest expense	247,501	235,251	243,465
Income tax benefit	78,173	(15,773)	133,902
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	550,559	538,320	511,047
Other comprehensive income (loss) — attributable to common shareholders	(5,700)	(9,388)	5,846
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	544,859	528,932	516,893
Pinnacle West
CONDENSED FINANCIAL STATEMENTS
Operating expenses	7,901	12,451	53,844
Other
Equity in earnings of subsidiaries	566,147	562,946	569,249
Other expense	(4,586)	(3,957)	(3,202)
Total	561,561	558,989	566,047
Interest expense	14,021	15,069	12,074
Income before income taxes	539,639	531,469	500,129
Income tax benefit	(10,920)	(6,851)	(10,918)
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	550,559	538,320	511,047
Other comprehensive income (loss) — attributable to common shareholders	(5,700)	(9,388)	5,846
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 544,859	$ 528,932	$ 516,893