SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CONDENSED FINANCIAL STATEMENTS
Operating revenues	$ 670,391	$ 1,190,787	$ 869,501	$ 740,530	$ 756,376	$ 1,268,034	$ 974,123	$ 692,714	$ 3,471,209	$ 3,691,247	$ 3,565,296
Operating expenses									2,799,249	2,917,560	2,655,533
Operating loss	11,997	403,290	196,589	60,084	66,884	433,307	242,162	31,334	671,960	773,687	909,763
Other
Total									86,803	109,040	54,142
Interest expense									235,251	243,465	219,796
Income tax benefit	(88,537)	53,266	17,080	2,418	6,795	84,333	44,039	(1,265)	(15,773)	133,902	258,272
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 63,981	$ 312,276	$ 144,145	$ 17,918	$ 26,076	$ 315,012	$ 166,738	$ 3,221	538,320	511,047	488,456
Other comprehensive income (loss)									(9,388)	5,846	(1,180)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS									528,932	516,893	487,276
Pinnacle West
CONDENSED FINANCIAL STATEMENTS
Operating revenues									0	0	119
Operating expenses									12,451	53,844	24,591
Operating loss									(12,451)	(53,844)	(24,472)
Other
Equity in earnings of subsidiaries									562,946	569,249	507,495
Other expense									(3,957)	(3,202)	(2,422)
Total									558,989	566,047	505,073
Interest expense									15,069	12,074	5,633
INCOME BEFORE INCOME TAXES									531,469	500,129	474,968
Income tax benefit									(6,851)	(10,918)	(13,488)
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS									538,320	511,047	488,456
Other comprehensive income (loss)									(9,388)	5,846	(1,180)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS									$ 528,932	$ 516,893	$ 487,276