SCHEDULE II - RESERVE FOR UNCOLLECTIBLES (Details) - Reserve for uncollectibles. - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
ARIZONA PUBLIC SERVICE COMPANY
Changes in reserve for uncollectibles
Balance at beginning of period	$ 4,069	$ 2,513	$ 3,037
Additions, Charged to cost and expenses	11,819	10,870	6,836
Additions, Charged to other accounts	0	0	0
Deductions	7,717	9,314	7,360
Balance at end of period	8,171	4,069	2,513
Pinnacle West
Changes in reserve for uncollectibles
Balance at beginning of period	4,069	2,513	3,037
Additions, Charged to cost and expenses	11,819	10,870	6,836
Additions, Charged to other accounts	0	0	0
Deductions	7,717	9,314	7,360
Balance at end of period	$ 8,171	$ 4,069	$ 2,513