Retirement Plans and Other Postretirement Benefits - Fair Value of Pinnacle West's Pension Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	$ 399,298	$ 429,391
Fair value of plan assets	2,835,549	2,829,485	$ 3,812,041
Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	885,721	893,285
Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	1,550,530	1,506,809
Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	107,201	106,356
Fair value of plan assets	696,494	652,287	$ 872,435
Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	391,019	371,731
Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	198,274	174,200
Cash and cash equivalents | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other		0
Fair value of plan assets		1,252
Cash and cash equivalents | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets		1,252
Cash and cash equivalents | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets		0
Cash and cash equivalents | Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other		0
Fair value of plan assets		204
Cash and cash equivalents | Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets		204
Cash and cash equivalents | Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets		0
Corporate | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	1,415,346	1,374,810
Corporate | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Corporate | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	1,415,346	1,374,810
Corporate | Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	189,902	166,879
Corporate | Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Corporate | Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	189,902	166,879
U.S. Treasury | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	622,273	635,245
U.S. Treasury | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	622,273	635,245
U.S. Treasury | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
U.S. Treasury | Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	207,665	221,936
U.S. Treasury | Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	207,665	221,936
U.S. Treasury | Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Other fixed income | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	135,184	131,999
Other fixed income | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Other fixed income | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	135,184	131,999
Other fixed income | Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	8,372	7,321
Other fixed income | Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Other fixed income | Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	8,372	7,321
Common stock equities | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	150,657	155,231
Common stock equities | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	150,657	155,231
Common stock equities | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Common stock equities | Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	139,952	127,493
Common stock equities | Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	139,952	127,493
Common stock equities | Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Mutual funds | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	112,791	101,557
Mutual funds | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	112,791	101,557
Mutual funds | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Mutual funds | Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0	0
Fair value of plan assets	22,256	18,824
Mutual funds | Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	22,256	18,824
Mutual funds | Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Equities | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	192,945	181,912
Fair value of plan assets	192,945	181,912
Equities | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Equities | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Equities | Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	81,724	73,956
Fair value of plan assets	81,724	73,956
Equities | Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Equities | Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Real estate | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	140,613	174,228
Fair value of plan assets	140,613	174,228
Real estate | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Real estate | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Real estate | Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	20,001	23,541
Fair value of plan assets	20,001	23,541
Real estate | Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Real estate | Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Partnerships | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other		13,359
Fair value of plan assets		13,359
Partnerships | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets		0
Partnerships | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets		0
Short-term investments and other | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	65,740	59,892
Fair value of plan assets	65,740	59,892
Short-term investments and other | Pension Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Short-term investments and other | Pension Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	0	0
Short-term investments and other | Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	5,476	8,859
Fair value of plan assets	26,622	12,133
Short-term investments and other | Other Benefits | Level 1
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	21,146	3,274
Short-term investments and other | Other Benefits | Level 2
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Gross fair value of plan assets	$ 0	$ 0