SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CONDENSED FINANCIAL STATEMENTS
OPERATING REVENUES	$ 756,376	$ 1,268,034	$ 974,123	$ 692,714	$ 759,659	$ 1,183,322	$ 944,587	$ 677,728	$ 3,691,247	$ 3,565,296	$ 3,498,682
Operating expenses									2,917,560	2,655,533	2,663,071
OPERATING INCOME	66,884	433,307	242,162	31,334	85,547	459,548	297,257	67,411	773,687	909,763	835,611
Other
Total									109,040	54,142	48,077
Interest expense									243,465	219,796	205,720
Income tax benefit	6,795	84,333	44,039	(1,265)	20,775	144,319	88,967	4,211	133,902	258,272	236,411
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 26,076	$ 315,012	$ 166,738	$ 3,221	$ 21,629	$ 276,072	$ 167,443	$ 23,312	511,047	488,456	442,034
Other comprehensive income (loss)									5,846	(1,180)	926
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS									516,893	487,276	442,960
Pinnacle West
CONDENSED FINANCIAL STATEMENTS
OPERATING REVENUES									0	119	370
Operating expenses									53,844	24,591	26,573
OPERATING INCOME									(53,844)	(24,472)	(26,203)
Other
Equity in earnings of subsidiaries									569,249	507,495	462,027
Other expense									(3,202)	(2,422)	(1,622)
Total									566,047	505,073	460,405
Interest expense									12,074	5,633	3,151
INCOME BEFORE INCOME TAXES									500,129	474,968	431,051
Income tax benefit									(10,918)	(13,488)	(10,983)
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS									511,047	488,456	442,034
Other comprehensive income (loss)									5,846	(1,180)	926
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS									$ 516,893	$ 487,276	$ 442,960