Investments in Nuclear Decommissioning Trusts and Other Special Use Funds - Schedule of Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
Variable Interest Entity | Pinnacle West Captive Insurance Cell
Nuclear decommissioning trust fund assets
Special use fund	$ 42,000		$ 40,000
APS
Nuclear decommissioning trust fund assets
Total	1,830,562		1,848,993
Total Unrealized Gains	419,039		451,809
Total Unrealized Losses	(18,483)		(14,994)
Amortized cost	1,270,000		1,265,000
Special use fund			40,300
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	4,736	$ 1,658
Realized losses	(2,797)	(2,761)
Proceeds from the sale of securities	512,234	485,814
APS | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Total	1,392,817		1,414,166
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	4,720	1,658
Realized losses	(2,797)	(2,761)
Proceeds from the sale of securities	447,883	416,601
APS | Other Special Use Funds
Nuclear decommissioning trust fund assets
Total	437,745		434,827
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	16	0
Realized losses	0	0
Proceeds from the sale of securities	64,351	69,213
APS | Captive Insurance Cell
Nuclear decommissioning trust fund assets
Total Unrealized Gains	2,800		3,200
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Proceeds from the sale of securities		$ 25,300
APS | Equity securities
Nuclear decommissioning trust fund assets
Equity securities	562,161		582,135
Total Unrealized Gains	407,542		433,044
Total Unrealized Losses	(139)		(1)
APS | Equity securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Equity securities	497,311		519,562
APS | Equity securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Equity securities	64,850		62,573
APS | Available for sale-fixed income securities
Nuclear decommissioning trust fund assets
Available for sale-fixed income securities	1,262,832		1,267,458
Total Unrealized Gains	11,497		18,765
Total Unrealized Losses	(18,344)		(14,993)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	180,414
1 year – 5 years	505,236
5 years – 10 years	184,518
Greater than 10 years	392,664
Total	1,262,832
APS | Available for sale-fixed income securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Available for sale-fixed income securities	891,949		898,403
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	32,191
1 year – 5 years	299,067
5 years – 10 years	168,027
Greater than 10 years	392,664
Total	891,949
APS | Available for sale-fixed income securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Available for sale-fixed income securities	370,883		369,055
APS | Available for sale-fixed income securities | Coal Reclamation Escrow Account
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	108,470
1 year – 5 years	49,806
5 years – 10 years	0
Greater than 10 years	0
Total	158,276
APS | Available for sale-fixed income securities | Active Union Employee Medical Account
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	39,753
1 year – 5 years	156,363
5 years – 10 years	16,491
Greater than 10 years	0
Total	212,607
APS | Other
Nuclear decommissioning trust fund assets
Other	5,569		(600)
Total Unrealized Gains	0		0
Total Unrealized Losses	0		0
APS | Other | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Other	3,557		(3,799)
APS | Other | Other Special Use Funds
Nuclear decommissioning trust fund assets
Other	2,012		$ 3,199
Pinnacle West | Variable Interest Entity | Pinnacle West Captive Insurance Cell
Nuclear decommissioning trust fund assets
Special use fund	$ 41,400