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, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2024 USD ($) $ / shares shares
Approximate remaining average useful lives of utility property
Depreciation		$ 723	$ 669	$ 632
Depreciation rates (as a percent)		3.13%	2.98%	3.03%
Allowance for Funds Used During Construction
Composite rate used to calculate AFUDC (as a percent)		6.23%	6.29%	5.75%
Income Taxes
Percent likelihood largest tax benefit amount is realized (greater than)		50.00%
Intangible Assets
Amortization expense		$ 136	$ 90	$ 84
Estimated amortization expense on existing intangible assets over the next five years
2025		106			$ 106
2026		77			77
2027		43			43
2028		25			25
2029		$ 14			$ 14
Remaining amortization period for intangible assets		5 years			5 years
Pinnacle West
Preferred Stock
Preferred stock, shares authorized (in shares) | shares		10,000,000			10,000,000
Preferred stock, shares outstanding (in shares) | shares		0			0
Arizona Public Service Company
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
Minimum
Approximate remaining average useful lives of utility property
Depreciation rates (as a percent)					1.37%
Maximum
Approximate remaining average useful lives of utility property
Depreciation rates (as a percent)					12.15%
Investments
Ownership percentage for classification as cost method investments by El Dorado		20.00%
Steam Generation
Approximate remaining average useful lives of utility property
Average useful life		11 years			11 years
Nuclear Plant
Approximate remaining average useful lives of utility property
Average useful life		25 years			25 years
Transmission
Approximate remaining average useful lives of utility property
Average useful life		38 years			38 years
Other Generation
Approximate remaining average useful lives of utility property
Average useful life		18 years			18 years
Distribution
Approximate remaining average useful lives of utility property
Average useful life		33 years			33 years
General Plant
Approximate remaining average useful lives of utility property
Average useful life		7 years			7 years