Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended			36 Months Ended
	May 31, 2014 $ / kWh	Dec. 31, 2025 USD ($) trust $ / shares shares	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2025 USD ($) trust $ / shares shares	Sep. 30, 2025 trust	Sep. 22, 2025 trust	Jun. 30, 2025 trust	Dec. 31, 1986 trust
Approximate remaining average useful lives of utility property
Depreciation		$ 732	$ 723	$ 669
Depreciation rates (as a percent)		3.06%	3.13%	2.98%
Allowance for Funds Used During Construction
Composite rate used to calculate AFUDC (as a percent)		6.67%	6.23%	6.29%
Income Taxes
Percent likelihood largest tax benefit amount is realized (greater than)		50.00%
Intangible Assets
Amortization expense		$ 157	$ 136	$ 90
Estimated amortization expense on existing intangible assets over the next five years
2026		109			$ 109
2027		75			75
2028		45			45
2029		26			26
2030		$ 14			$ 14
Remaining amortization period for intangible assets		6 years			6 years
Minimum
Approximate remaining average useful lives of utility property
Depreciation rates (as a percent)					1.37%
Investments
Ownership percentage for classification as cost method investments by El Dorado		3.00%
Maximum
Approximate remaining average useful lives of utility property
Depreciation rates (as a percent)					12.37%
Investments
Ownership percentage for classification as cost method investments by El Dorado		5.00%
Steam Generation
Approximate remaining average useful lives of utility property
Average useful life		21 years			21 years
Nuclear Plant
Approximate remaining average useful lives of utility property
Average useful life		30 years			30 years
Other Generation
Approximate remaining average useful lives of utility property
Average useful life		16 years			16 years
Transmission
Approximate remaining average useful lives of utility property
Average useful life		34 years			34 years
Distribution
Approximate remaining average useful lives of utility property
Average useful life		33 years			33 years
Energy Storage
Approximate remaining average useful lives of utility property
Average useful life		19 years			19 years
Solar Plant
Approximate remaining average useful lives of utility property
Average useful life		28 years			28 years
General Plant
Approximate remaining average useful lives of utility property
Average useful life		10 years			10 years
Pinnacle West Consolidated
Preferred Stock
Preferred stock, shares authorized (in shares) | shares		10,000,000			10,000,000
Preferred stock, shares outstanding (in shares) | shares		0			0
APS
Nuclear Fuel
Charges for the permanent disposal of spent nuclear fuel (in dollars per kWh) | $ / kWh	0.001
Preferred Stock
Preferred stock, shares authorized (in shares) | shares		15,535,000			15,535,000
Preferred stock, shares outstanding (in shares) | shares		0			0
Preferred stock par or stated value per share 1 (in dollars per share) | $ / shares		$ 25			$ 25
Preferred stock par or stated value per share 2 (in dollars per share) | $ / shares		50			50
Preferred stock par or stated value per share 3 (in dollars per share) | $ / shares		$ 100			$ 100
APS | Variable Interest Entity
Utility Plant and Depreciation [Line Items]
Number of VIE lessor trusts acquired | trust						2	2
Number of VIE lessor trusts | trust		1			1			2	3