SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - Balance Sheets (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 10,283,000	$ 5,766,000
Accounts receivable	266,426,000	267,887,000
Income tax receivable	21,727,000	0
Other current assets	61,958,000	56,128,000
Total current assets	1,030,030,000	924,991,000
Investments and other assets
Other assets	96,953,000	103,247,000
Total investments and other assets	1,352,823,000	1,190,482,000
Total Assets	18,479,247,000	17,664,202,000
Current liabilities
Accounts payable	346,448,000	277,336,000
Accrued taxes	144,899,000	154,819,000
Common dividends payable	87,982,000	82,675,000
Short-term borrowings	114,675,000	76,400,000
Current maturities of long-term debt	800,000,000	500,000,000
Operating lease liabilities	12,713,000	0
Other current liabilities	168,323,000	184,229,000
Total current liabilities	2,078,365,000	1,648,964,000
Deferred credits and other
Long-term debt less current maturities (Note 7)	4,832,558,000	4,638,232,000
Operating lease liabilities	51,872,000	0
Other	159,844,000	147,640,000
Total deferred credits and other	6,015,136,000	6,028,301,000
COMMITMENTS AND CONTINGENCIES (SEE NOTES)
Common stock equity
Common stock	2,659,561,000	2,634,265,000
Accumulated other comprehensive loss	(57,096,000)	(47,708,000)
Retained earnings	2,837,610,000	2,641,183,000
Total shareholders’ equity	5,430,648,000	5,222,915,000
Noncontrolling interests	122,540,000	125,790,000
Total equity	5,553,188,000	5,348,705,000	$ 5,135,730,000	$ 4,935,912,000
Total Liabilities and Equity	18,479,247,000	17,664,202,000
Pinnacle West
Current assets
Cash and cash equivalents	19,000	41,000
Accounts receivable	104,640,000	99,989,000
Income tax receivable	15,905,000	32,737,000
Other current assets	401,000	1,502,000
Total current assets	120,965,000	134,269,000
Investments and other assets
Investments in subsidiaries	6,067,957,000	5,859,834,000
Deferred income taxes	40,757,000	5,243,000
Other assets	50,139,000	34,910,000
Total investments and other assets	6,158,853,000	5,899,987,000
Total Assets	6,279,818,000	6,034,256,000
Current liabilities
Accounts payable	7,634,000	9,565,000
Accrued taxes	8,573,000	9,006,000
Common dividends payable	87,982,000	82,675,000
Short-term borrowings	114,675,000	76,400,000
Current maturities of long-term debt	450,000,000	0
Operating lease liabilities	81,000	0
Other current liabilities	15,126,000	19,215,000
Total current liabilities	684,071,000	196,861,000
Deferred credits and other
Long-term debt less current maturities (Note 7)	(575,000)	448,796,000
Pension liabilities	17,942,000	17,766,000
Operating lease liabilities	1,780,000	0
Other	23,412,000	22,128,000
Total deferred credits and other	43,134,000	39,894,000
COMMITMENTS AND CONTINGENCIES (SEE NOTES)
Common stock equity
Common stock	2,650,134,000	2,629,440,000
Accumulated other comprehensive loss	(57,096,000)	(47,708,000)
Retained earnings	2,837,610,000	2,641,183,000
Total shareholders’ equity	5,430,648,000	5,222,915,000
Noncontrolling interests	122,540,000	125,790,000
Total equity	5,553,188,000	5,348,705,000
Total Liabilities and Equity	$ 6,279,818,000	$ 6,034,256,000