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		6 Months Ended		12 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Variable Interest Entity | Pinnacle West Captive Insurance Cell
Fair value of fixed income securities, summarized by contractual maturities
Special use fund	$ 39,000		$ 39,000		$ 34,000
APS
Nuclear decommissioning trust fund assets
Total	1,761,190		1,761,190		1,691,202
Total Unrealized Gains			400,706		366,844
Total Unrealized Losses			(19,502)		(32,136)
Amortized cost	1,227,000		1,227,000		1,224,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	1,702	$ 8,943	3,360	$ 63,515
Realized losses	(2,611)	(3,706)	(5,372)	(6,521)
Proceeds from the sale of securities	433,830	328,505	919,644	772,375
Fair value of fixed income securities, summarized by contractual maturities
Special use fund					34,200
APS | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Total	1,337,858		1,337,858		1,282,845
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	1,702	8,943	3,360	63,435
Realized losses	(2,611)	(3,706)	(5,372)	(6,521)
Proceeds from the sale of securities	342,313	270,631	758,914	648,453
APS | Other Special Use Funds
Nuclear decommissioning trust fund assets
Total	423,332		423,332		408,357
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	0	0	0	80
Realized losses	0	0	0	0
Proceeds from the sale of securities	91,517	$ 57,874	160,730	$ 123,922
APS | Captive Insurance Cell
Nuclear decommissioning trust fund assets
Total Unrealized Gains			2,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Proceeds from the sale of securities	25,200		50,500
APS | Equity securities
Nuclear decommissioning trust fund assets
Equity securities	532,289		532,289		460,432
Total Unrealized Gains			385,464		359,127
Total Unrealized Losses			0		(176)
APS | Equity securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Equity securities	467,967		467,967		435,470
APS | Equity securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Equity securities	64,322		64,322		24,962
APS | Available for sale-fixed income securities
Nuclear decommissioning trust fund assets
Available for sale-fixed income securities	1,222,381		1,222,381		1,199,584
Total Unrealized Gains			15,242		7,717
Total Unrealized Losses			(19,502)		(31,960)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	142,870		142,870
1 year – 5 years	494,787		494,787
5 years – 10 years	187,732		187,732
Greater than 10 years	396,992		396,992
Total	1,222,381		1,222,381
APS | Available for sale-fixed income securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Available for sale-fixed income securities	866,215		866,215		844,040
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	19,613		19,613
1 year – 5 years	278,017		278,017
5 years – 10 years	171,593		171,593
Greater than 10 years	396,992		396,992
Total	866,215		866,215
APS | Available for sale-fixed income securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Available for sale-fixed income securities	356,166		356,166		355,544
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	83,392		83,392
1 year – 5 years	58,611		58,611
5 years – 10 years	0		0
Greater than 10 years	0		0
Total	142,003		142,003
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	39,865		39,865
1 year – 5 years	158,159		158,159
5 years – 10 years	16,139		16,139
Greater than 10 years	0		0
Total	214,163		214,163
APS | Other
Nuclear decommissioning trust fund assets
Other	6,520		6,520		31,186
Total Unrealized Gains			0		0
Total Unrealized Losses			0		0
APS | Other | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Other	3,676		3,676		3,335
APS | Other | Other Special Use Funds
Nuclear decommissioning trust fund assets
Other	2,844		2,844		$ 27,851
Pinnacle West | Variable Interest Entity | Pinnacle West Captive Insurance Cell
Fair value of fixed income securities, summarized by contractual maturities
Special use fund	$ 38,500		$ 38,500