Retirement Plans and Other Postretirement Benefits - Schedule of Fair Value of Pinnacle West's Pension Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	$ 432,742	$ 399,298
Fair value of plan assets	2,639,862	2,835,549	$ 2,829,485
Pension Plans | 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	748,033	885,721
Pension Plans | 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	1,459,087	1,550,530
Other Benefits Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	165,813	107,201
Fair value of plan assets	702,192	696,494	$ 652,287
Other Benefits Plans | 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	337,359	391,019
Other Benefits Plans | 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	199,020	198,274
Cash and cash equivalents | Pension Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0
Fair value of plan assets	9,055
Cash and cash equivalents | Pension Plans | 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	9,055
Cash and cash equivalents | Pension Plans | 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 Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	0
Fair value of plan assets	840
Cash and cash equivalents | Other Benefits Plans | 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	840
Cash and cash equivalents | Other Benefits Plans | 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 Plans
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	1,325,833	1,415,346
Corporate | Pension Plans | 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 Plans | 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	1,325,833	1,415,346
Corporate | Other Benefits Plans
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	186,435	189,902
Corporate | Other Benefits Plans | 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 Plans | 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	186,435	189,902
U.S. Treasury | Pension Plans
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	561,317	622,273
U.S. Treasury | Pension Plans | 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	561,317	622,273
U.S. Treasury | Pension Plans | 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 Plans
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	204,274	207,665
U.S. Treasury | Other Benefits Plans | 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	204,274	207,665
U.S. Treasury | Other Benefits Plans | 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 | Pension Plans
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	133,254	135,184
Other | Pension Plans | 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 | Pension Plans | 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	133,254	135,184
Other | Other Benefits Plans
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	12,585	8,372
Other | Other Benefits Plans | 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 | Other Benefits Plans | 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	12,585	8,372
Common stock equities | Pension Plans
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	74,939	150,657
Common stock equities | Pension Plans | 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	74,939	150,657
Common stock equities | Pension Plans | 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 Plans
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	89,685	139,952
Common stock equities | Other Benefits Plans | 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	89,685	139,952
Common stock equities | Other Benefits Plans | 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 Plans
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	102,722	112,791
Mutual funds | Pension Plans | 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	102,722	112,791
Mutual funds | Pension Plans | 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 Plans
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	23,415	22,256
Mutual funds | Other Benefits Plans | 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	23,415	22,256
Mutual funds | Other Benefits Plans | 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 Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	244,734	192,945
Fair value of plan assets	244,734	192,945
Equities | Pension Plans | 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 Plans | 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 Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	140,178	81,724
Fair value of plan assets	140,178	81,724
Equities | Other Benefits Plans | 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 Plans | 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 Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	127,397	140,613
Fair value of plan assets	127,397	140,613
Real estate | Pension Plans | 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 Plans | 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 Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	19,474	20,001
Fair value of plan assets	19,474	20,001
Real estate | Other Benefits Plans | 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 Plans | 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 | Pension Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	60,611	65,740
Fair value of plan assets	60,611	65,740
Short-term investments and other | Pension Plans | 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 Plans | 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 Plans
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	6,161	5,476
Fair value of plan assets	25,306	26,622
Short-term investments and other | Other Benefits Plans | 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	19,145	21,146
Short-term investments and other | Other Benefits Plans | 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