Pinnacle West Capital (PNW) 10-K 27 Feb 24 2023 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2023	Feb. 21, 2024	Jun. 30, 2023
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-8962
Entity Registrant Name	PINNACLE WEST CAPITAL CORPORATION
Entity Tax Identification Number	86-0512431
Entity Incorporation, State or Country Code	AZ
Entity Address, Address Line One	400 North Fifth Street, P.O. Box 53999
Entity Address, City or Town	Phoenix
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85072-3999
City Area Code	(602)
Local Phone Number	250-1000
Title of 12(b) Security	Common Stock,No Par Value
Trading Symbol	PNW
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 9,215,155,738
Entity Common Stock, Shares Outstanding		113,427,367
Documents Incorporated by Reference	Portions of Pinnacle West Capital Corporation’s definitive Proxy Statement relating to its Annual Meeting of Shareholders to be held on May 22, 2024 are incorporated by reference into Part III hereof.
Entity Central Index Key	0000764622
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Arizona Public Service Company
Entity Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Entity File Number	1-4473
Entity Registrant Name	ARIZONA PUBLIC SERVICE COMPANY
Entity Tax Identification Number	86-0011170
Entity Incorporation, State or Country Code	AZ
Entity Address, Address Line One	400 North Fifth Street, P.O. Box 53999
Entity Address, City or Town	Phoenix
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85072-3999
City Area Code	(602)
Local Phone Number	250-1000
Title of 12(g) Security	Common Stock
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		71,264,947
Documents Incorporated by Reference	Arizona Public Service Company meets the conditions set forth in General Instruction I(1)(a) and (b) of Form 10-K and is therefore filing this form with the reduced disclosure format allowed under that General Instruction.
Entity Central Index Key	0000007286
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Auditor [Line Items]
Auditor Name	Deloitte & Touche LLP
Auditor Location	Tempe, Arizona
Auditor Firm ID	34
Arizona Public Service Company
Auditor [Line Items]
Auditor Name	Deloitte & Touche LLP
Auditor Location	Tempe, Arizona
Auditor Firm ID	34

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
OPERATING REVENUES (Note 2)	$ 4,695,991	$ 4,324,385	$ 3,803,835
OPERATING EXPENSES
Fuel and purchased power	1,792,657	1,629,343	1,152,551
Operations and maintenance	1,058,725	987,072	954,067
Depreciation and amortization	794,043	753,195	650,875
Taxes other than income taxes	224,013	220,370	234,639
Other expenses	1,913	2,494	6,393
Total	3,871,351	3,592,474	2,998,525
OPERATING INCOME	824,640	731,911	805,310
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction (Note 1)	53,118	45,263	41,737
Pension and other postretirement non-service credits, net (Note 7)	40,648	98,487	112,541
Other income (Note 16)	33,666	7,916	45,100
Other expense (Note 16)	(25,056)	(52,385)	(25,396)
Total	102,376	99,281	173,982
INTEREST EXPENSE
Interest charges	374,887	283,569	254,314
Allowance for borrowed funds used during construction (Note 1)	(43,564)	(28,030)	(21,052)
Total	331,323	255,539	233,262
INCOME BEFORE INCOME TAXES	595,693	575,653	746,030
INCOME TAXES (Note 4)	76,912	74,827	110,086
NET INCOME	518,781	500,826	635,944
Less: Net income attributable to noncontrolling interests (Note 17)	17,224	17,224	17,224
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 501,557	$ 483,602	$ 618,720
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING — BASIC (in shares)	113,442	113,196	112,910
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING — DILUTED (in shares)	113,804	113,416	113,192
EARNINGS PER WEIGHTED-AVERAGE COMMON SHARE OUTSTANDING
Net income attributable to common shareholders - basic (in dollars per share)	$ 4.42	$ 4.27	$ 5.48
Net income attributable to common shareholders — diluted (in dollars per share)	$ 4.41	$ 4.26	$ 5.47

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 518,781	$ 500,826	$ 635,944
Derivative instruments:
Net unrealized gain, net of tax expense of $234, $615, and $360	713	1,873	1,095
Pension and other postretirement benefits activity, net of tax benefit (expense) of $801, $(7,078), and $(2,256) (Note 7)	(2,422)	21,553	6,840
Total other comprehensive income (loss)	(1,709)	23,426	7,935
COMPREHENSIVE INCOME	517,072	524,252	643,879
Less: Comprehensive income attributable to noncontrolling interests	17,224	17,224	17,224
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 499,848	$ 507,028	$ 626,655

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net unrealized gain, net of tax expense	$ 234	$ 615	$ 360
Pension and other postretirement benefits activity, tax benefit (expense)	$ 801	$ (7,078)	$ (2,256)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
CURRENT ASSETS
Cash and cash equivalents	$ 4,955	$ 4,832
Customer and other receivables	513,892	453,209
Accrued unbilled revenues	167,553	164,764
Allowance for doubtful accounts (Note 2)	(22,433)	(23,778)
Materials and supplies (at average cost)	444,344	410,481
Fossil fuel (at average cost)	49,203	40,155
Income tax receivable (Note 4)	332	14,086
Assets from risk management activities (Note 15)	6,808	87,835
Assets held for sale (Note 20)	35,139	0
Deferred fuel and purchased power regulatory asset (Note 3)	463,195	460,561
Other regulatory assets (Note 3)	162,562	78,318
Other current assets	101,417	60,091
Total current assets	1,926,967	1,750,554
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trusts (Notes 12 and 18)	1,201,246	1,073,410
Other special use funds (Notes 12 and 18)	362,781	347,231
Assets from risk management activities (Note 15)	0	44,394
Other assets	102,845	125,672
Total investments and other assets	1,666,872	1,590,707
PROPERTY, PLANT AND EQUIPMENT (Notes 1, 6 and 9)
Plant in service and held for future use	24,211,167	22,452,146
Accumulated depreciation and amortization	(8,408,040)	(7,929,878)
Net	15,803,127	14,522,268
Construction work in progress	1,724,004	1,882,791
Palo Verde sale leaseback, net of accumulated depreciation of $264,624 and $260,754 (Note 17)	86,426	90,296
Intangible assets, net of accumulated amortization of $885,505 and $817,961	267,110	258,880
Nuclear fuel, net of accumulated amortization of $118,074 and $126,157	99,490	100,119
Total property, plant and equipment	17,980,157	16,854,354
DEFERRED DEBITS
Regulatory assets (Notes 1, 3, 4 and 7)	1,390,279	1,283,221
Operating lease right-of-use assets (Note 8)	1,309,975	801,688
Assets for pension and other postretirement benefits (Note 7)	323,438	396,599
Other	63,465	46,282
Total deferred debits	3,087,157	2,527,790
TOTAL ASSETS	24,661,153	22,723,405
CURRENT LIABILITIES
Accounts payable	442,455	430,425
Accrued taxes	166,833	164,440
Accrued interest	72,916	61,217
Common dividends payable	99,813	97,895
Short-term borrowings (Note 5)	609,500	340,720
Current maturities of long-term debt (Note 6)	875,000	50,685
Customer deposits	42,037	41,769
Liabilities from risk management activities (Note 15)	80,913	37,697
Liabilities for asset retirements (Note 11)	28,550	12,232
Operating lease liabilities (Note 8)	67,883	105,210
Regulatory liabilities (Note 3)	209,923	271,575
Other current liabilities	193,524	148,276
Total current liabilities	2,889,347	1,762,141
LONG-TERM DEBT LESS CURRENT MATURITIES (Note 6)	7,540,622	7,741,286
DEFERRED CREDITS AND OTHER
Deferred income taxes (Note 4)	2,416,480	2,384,421
Regulatory liabilities (Notes 1, 3, 4 and 7)	1,965,865	2,061,776
Liabilities for asset retirements (Note 11)	937,451	785,530
Liabilities for pension benefits (Note 7)	112,702	116,286
Liabilities from risk management activities (Note 15)	42,975	4,749
Customer advances	533,580	422,103
Coal mine reclamation	184,007	179,255
Deferred investment tax credit	257,743	180,677
Unrecognized tax benefits (Note 4)	33,861	38,658
Operating lease liabilities (Note 8)	1,210,189	639,247
Other	251,469	247,400
Total deferred credits and other	7,946,322	7,060,102
COMMITMENTS AND CONTINGENCIES (Note 10)
EQUITY
Common stock, no par value; authorized 150,000,000 shares, 113,537,689 and 113,247,189 issued at respective dates	2,752,676	2,724,740
Treasury stock at cost; 113,272 and 73,613 shares at respective dates	(8,185)	(5,005)
Total common stock	2,744,491	2,719,735
Retained earnings	3,466,317	3,360,347
Accumulated other comprehensive loss (Note 19)	(33,144)	(31,435)
Total shareholders’ equity	6,177,664	6,048,647
Noncontrolling interests (Note 17)	107,198	111,229
Total equity	6,284,862	6,159,876
TOTAL LIABILITIES AND EQUITY	$ 24,661,153	$ 22,723,405

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
PROPERTY, PLANT AND EQUIPMENT
Accumulated depreciation of Palo Verde sale leaseback	$ 264,624	$ 260,754
Accumulated amortization on intangible assets	885,505	817,961
Accumulated amortization on nuclear fuel	$ 118,074	$ 126,157
EQUITY
Common stock, authorized shares (in shares)	150,000,000	150,000,000
Common stock, issued shares (in shares)	113,537,689	113,247,189
Treasury stock (in shares)	113,272	73,613

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 518,781	$ 500,826	$ 635,944
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale relating to BCE	(6,423)	0	0
Depreciation and amortization including nuclear fuel	854,136	817,814	719,141
Deferred fuel and purchased power	(549,877)	(291,992)	(256,871)
Deferred fuel and purchased power amortization	547,243	219,579	44,557
Allowance for equity funds used during construction	(53,118)	(45,263)	(41,737)
Deferred income taxes	(24,310)	43,202	117,471
Deferred investment tax credit	77,065	(5,893)	(4,802)
Change in derivative instruments fair value	(777)	777	0
Stock compensation	17,341	15,942	18,460
Changes in current assets and liabilities:
Customer and other receivables	(61,983)	(63,869)	(72,559)
Accrued unbilled revenues	(2,789)	(30,784)	(1,783)
Materials, supplies and fossil fuel	(42,911)	(83,469)	(32,870)
Income tax receivable	13,754	(6,572)	(722)
Other current assets	(19,550)	76,089	(22,770)
Accounts payable	(75,623)	90,076	20,267
Accrued taxes	2,393	(4,205)	9,094
Other current liabilities	40,510	(1,856)	(51,736)
Change in long-term regulatory assets	53,112	12,432	(17,012)
Change in long-term regulatory liabilities	28,495	(332,470)	57,549
Change in other long-term assets	(195,598)	159,030	(345,470)
Change in operating lease assets	90,525	105,359	116,009
Change in other long-term liabilities	63,080	170,359	78,219
Change in operating lease liabilities	(65,779)	(103,671)	(108,365)
Net cash provided by operating activities	1,207,697	1,241,441	860,014
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,846,370)	(1,707,490)	(1,473,475)
Contributions in aid of construction	180,866	137,436	105,654
Proceeds from sale relating to BCE	23,400	0	0
Allowance for borrowed funds used during construction	(43,564)	(28,030)	(21,052)
Proceeds from nuclear decommissioning trust sales and other special use funds	1,679,722	1,207,713	1,720,966
Investment in nuclear decommissioning trust and other special use funds	(1,681,845)	(1,212,063)	(1,725,480)
Other	(6,458)	(15,612)	6,458
Net cash used for investing activities	(1,694,249)	(1,618,046)	(1,386,929)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	689,349	875,537	746,999
Repayment of long-term debt	(32,740)	(150,000)	0
Short-term borrowings and (repayments) — net	241,900	48,720	142,000
Short-term debt repayments under revolving credit facility	0	0	(19,000)
Dividends paid on common stock	(386,486)	(378,881)	(369,478)
Common stock equity issuance and purchases — net	(4,093)	(2,653)	(2,350)
Distributions to noncontrolling interests	(21,255)	(21,255)	(21,255)
Net cash provided by financing activities	486,675	371,468	476,916
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	123	(5,137)	(49,999)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	4,832	9,969	59,968
CASH AND CASH EQUIVALENTS AT END OF YEAR	$ 4,955	$ 4,832	$ 9,969

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands		Total	Common Stock	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2020			112,760,051
Beginning balance at Dec. 31, 2020		$ 5,752,793	$ 2,677,482	$ (6,289)	$ 3,025,106	$ (62,796)	$ 119,290
Beginning balance (in shares) at Dec. 31, 2020				(72,006)
Increase (Decrease) in Shareholders' Equity
Net income		635,944			618,720		17,224
Other comprehensive income		7,935				7,935
Dividends on common stock		(379,108)			(379,108)
Issuance of common stock (in shares)			254,477
Issuance of common stock		25,261	$ 25,261
Purchase of treasury stock (in shares)	[1]			(68,892)
Purchase of treasury stock	[1]	(4,655)		$ (4,655)
Reissuance of treasury stock for stock-based compensation and other (in shares)				53,290
Reissuance of treasury stock for stock-based compensation and other		4,543		$ 4,543
Capital activities by noncontrolling interests		(21,255)					(21,255)
Other		2			1		1
Ending balance (in shares) at Dec. 31, 2021			113,014,528
Ending balance at Dec. 31, 2021		6,021,460	$ 2,702,743	$ (6,401)	3,264,719	(54,861)	115,260
Ending balance (in shares) at Dec. 31, 2021				(87,608)
Increase (Decrease) in Shareholders' Equity
Net income		500,826			483,602		17,224
Other comprehensive income		23,426				23,426
Dividends on common stock		(387,975)			(387,975)
Issuance of common stock (in shares)			232,661
Issuance of common stock		21,996	$ 21,996
Purchase of treasury stock (in shares)	[1]			(77,152)
Purchase of treasury stock	[1]	(5,152)		$ (5,152)
Reissuance of treasury stock for stock-based compensation and other (in shares)				91,147
Reissuance of treasury stock for stock-based compensation and other		6,548		$ 6,548
Capital activities by noncontrolling interests		(21,255)					(21,255)
Other		$ 2	$ 1		1
Ending balance (in shares) at Dec. 31, 2022		113,247,189	113,247,189
Ending balance at Dec. 31, 2022		$ 6,159,876	$ 2,724,740	$ (5,005)	3,360,347	(31,435)	111,229
Ending balance (in shares) at Dec. 31, 2022		(73,613)		(73,613)
Increase (Decrease) in Shareholders' Equity
Net income		$ 518,781			501,557		17,224
Other comprehensive income		(1,709)				(1,709)
Dividends on common stock		(395,585)			(395,585)
Issuance of common stock (in shares)			290,500
Issuance of common stock		27,936	$ 27,936
Purchase of treasury stock (in shares)	[1]			(72,180)
Purchase of treasury stock	[1]	(5,466)		$ (5,466)
Reissuance of treasury stock for stock-based compensation and other (in shares)				32,521
Reissuance of treasury stock for stock-based compensation and other		2,287		$ 2,287
Capital activities by noncontrolling interests		(21,255)					(21,255)
Other		$ (3)		(1)	(2)
Ending balance (in shares) at Dec. 31, 2023		113,537,689	113,537,689
Ending balance at Dec. 31, 2023		$ 6,284,862	$ 2,752,676	$ (8,185)	$ 3,466,317	$ (33,144)	$ 107,198
Ending balance (in shares) at Dec. 31, 2023		(113,272)		(113,272)
[1] Primarily represents shares of common stock withheld from certain stock awards for tax purposes.

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in dollars per share)	$ 3.49	$ 3.43	$ 3.36

APS - CONSOLIDATED STATEMENTS O

APS - CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
OPERATING REVENUES (Note 2)	$ 4,695,991	$ 4,324,385	$ 3,803,835
OPERATING EXPENSES
Fuel and purchased power	1,792,657	1,629,343	1,152,551
Operations and maintenance	1,058,725	987,072	954,067
Depreciation and amortization	794,043	753,195	650,875
Taxes other than income taxes	224,013	220,370	234,639
Other expenses	1,913	2,494	6,393
Total	3,871,351	3,592,474	2,998,525
OPERATING INCOME	824,640	731,911	805,310
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction (Note 1)	53,118	45,263	41,737
Pension and other postretirement non-service credits, net (Note 7)	40,648	98,487	112,541
Other income (Note 16)	33,666	7,916	45,100
Other expense (Note 16)	(25,056)	(52,385)	(25,396)
Total	102,376	99,281	173,982
INTEREST EXPENSE
Interest charges	374,887	283,569	254,314
Allowance for borrowed funds used during construction (Note 1)	(43,564)	(28,030)	(21,052)
Total	331,323	255,539	233,262
INCOME BEFORE INCOME TAXES	595,693	575,653	746,030
INCOME TAXES (Note 4)	76,912	74,827	110,086
NET INCOME	518,781	500,826	635,944
Less: Net income attributable to noncontrolling interests (Note 17)	17,224	17,224	17,224
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	501,557	483,602	618,720
Arizona Public Service Company
OPERATING REVENUES (Note 2)	4,695,991	4,324,385	3,803,835
OPERATING EXPENSES
Fuel and purchased power	1,792,657	1,629,343	1,152,551
Operations and maintenance	1,043,570	974,220	940,588
Depreciation and amortization	793,958	753,110	650,773
Taxes other than income taxes	223,962	220,277	234,569
Other expenses	1,913	2,494	6,393
Total	3,856,060	3,579,444	2,984,874
OPERATING INCOME	839,931	744,941	818,961
OTHER INCOME (DEDUCTIONS)
Allowance for equity funds used during construction (Note 1)	53,118	45,263	41,737
Pension and other postretirement non-service credits, net (Note 7)	41,577	98,945	112,742
Other income (Note 16)	27,072	5,888	43,053
Other expense (Note 16)	(18,264)	(26,108)	(18,897)
Total	103,503	123,988	178,635
INTEREST EXPENSE
Interest charges	323,719	262,815	243,592
Allowance for borrowed funds used during construction (Note 1)	(39,030)	(26,839)	(21,052)
Total	284,689	235,976	222,540
INCOME BEFORE INCOME TAXES	658,745	632,953	775,056
INCOME TAXES (Note 4)	94,184	90,800	125,553
NET INCOME	564,561	542,153	649,503
Less: Net income attributable to noncontrolling interests (Note 17)	17,224	17,224	17,224
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 547,337	$ 524,929	$ 632,279

APS - CONSOLIDATED STATEMENTS_2

APS - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
NET INCOME	$ 518,781	$ 500,826	$ 635,944
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX
Pension and other postretirement benefits activity, net of tax benefit (expense) of $536, $(6,332), and $(1,990) (Note 7)	(2,422)	21,553	6,840
Total other comprehensive income (loss)	(1,709)	23,426	7,935
COMPREHENSIVE INCOME	517,072	524,252	643,879
Less: Comprehensive income attributable to noncontrolling interests	17,224	17,224	17,224
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	499,848	507,028	626,655
Arizona Public Service Company
NET INCOME	564,561	542,153	649,503
OTHER COMPREHENSIVE INCOME (LOSS), NET OF TAX
Pension and other postretirement benefits activity, net of tax benefit (expense) of $536, $(6,332), and $(1,990) (Note 7)	(1,623)	19,284	6,038
Total other comprehensive income (loss)	(1,623)	19,284	6,038
COMPREHENSIVE INCOME	562,938	561,437	655,541
Less: Comprehensive income attributable to noncontrolling interests	17,224	17,224	17,224
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 545,714	$ 544,213	$ 638,317

APS - CONSOLIDATED STATEMENTS_3

APS - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension and other postretirement benefits activity, tax benefit (expense)	$ 801	$ (7,078)	$ (2,256)
Arizona Public Service Company
Pension and other postretirement benefits activity, tax benefit (expense)	$ 536	$ (6,332)	$ (1,990)

APS - CONSOLIDATED BALANCE SHEE

APS - CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
PROPERTY, PLANT AND EQUIPMENT (Notes 1, 6 and 9)
Plant in service and held for future use	$ 24,211,167	$ 22,452,146
Accumulated depreciation and amortization	(8,408,040)	(7,929,878)
Net	15,803,127	14,522,268
Construction work in progress	1,724,004	1,882,791
Palo Verde sale leaseback, net of accumulated depreciation of $264,624 and $260,754 (Note 17)	86,426	90,296
Intangible assets, net of accumulated amortization of $884,371 and $816,827	267,110	258,880
Nuclear fuel, net of accumulated amortization of $118,074 and $126,157	99,490	100,119
Total property, plant and equipment	17,980,157	16,854,354
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trusts (Notes 12 and 18)	1,201,246	1,073,410
Other special use funds (Notes 12 and 18)	362,781	347,231
Assets from risk management activities (Note 15)	0	44,394
Other assets	102,845	125,672
Total investments and other assets	1,666,872	1,590,707
CURRENT ASSETS
Cash and cash equivalents	4,955	4,832
Customer and other receivables	513,892	453,209
Accrued unbilled revenues	167,553	164,764
Allowance for doubtful accounts (Note 2)	(22,433)	(23,778)
Materials and supplies (at average cost)	444,344	410,481
Fossil fuel (at average cost)	49,203	40,155
Income tax receivable (Note 4)	332	14,086
Assets from risk management activities (Note 15)	6,808	87,835
Deferred fuel and purchased power regulatory asset (Note 3)	463,195	460,561
Other regulatory assets (Note 3)	162,562	78,318
Other current assets	101,417	60,091
Total current assets	1,926,967	1,750,554
DEFERRED DEBITS
Regulatory assets (Notes 1, 3, 4 and 7)	1,390,279	1,283,221
Operating lease right-of-use assets (Note 8)	1,309,975	801,688
Assets for pension and other postretirement benefits (Note 7)	323,438	396,599
Other	63,465	46,282
Total deferred debits	3,087,157	2,527,790
TOTAL ASSETS	24,661,153	22,723,405
CAPITALIZATION
Retained earnings	3,466,317	3,360,347
Accumulated other comprehensive loss (Note 19)	(33,144)	(31,435)
Total shareholders’ equity	6,177,664	6,048,647
Noncontrolling interests (Note 17)	107,198	111,229
Total equity	6,284,862	6,159,876
Long-term debt less current maturities (Note 6)	7,540,622	7,741,286
CURRENT LIABILITIES
Short-term borrowings (Note 5)	609,500	340,720
Accounts payable	442,455	430,425
Accrued taxes	166,833	164,440
Accrued interest	72,916	61,217
Common dividends payable	99,813	97,895
Customer deposits	42,037	41,769
Liabilities from risk management activities (Note 15)	80,913	37,697
Liabilities for asset retirements (Note 11)	28,550	12,232
Operating lease liabilities (Note 8)	67,883	105,210
Regulatory liabilities (Note 3)	209,923	271,575
Other current liabilities	193,524	148,276
Total current liabilities	2,889,347	1,762,141
DEFERRED CREDITS AND OTHER
Deferred income taxes (Note 4)	2,416,480	2,384,421
Regulatory liabilities (Notes 1, 3, 4 and 7)	1,965,865	2,061,776
Liabilities for asset retirements (Note 11)	937,451	785,530
Liabilities for pension benefits (Note 7)	112,702	116,286
Customer advances	533,580	422,103
Coal mine reclamation	184,007	179,255
Deferred investment tax credit	257,743	180,677
Unrecognized tax benefits (Note 4)	33,861	38,658
Operating lease liabilities (Note 8)	1,210,189	639,247
Other	251,469	247,400
Total deferred credits and other	7,946,322	7,060,102
COMMITMENTS AND CONTINGENCIES (Note 10)
TOTAL LIABILITIES AND EQUITY	24,661,153	22,723,405
Current maturities of long-term debt (Note 6)	875,000	50,685
Liabilities from risk management activities (Note 15)	42,975	4,749
Arizona Public Service Company
PROPERTY, PLANT AND EQUIPMENT (Notes 1, 6 and 9)
Plant in service and held for future use	24,207,706	22,448,685
Accumulated depreciation and amortization	(8,404,721)	(7,926,575)
Net	15,802,985	14,522,110
Construction work in progress	1,724,004	1,829,004
Palo Verde sale leaseback, net of accumulated depreciation of $264,624 and $260,754 (Note 17)	86,426	90,296
Intangible assets, net of accumulated amortization of $884,371 and $816,827	266,955	258,725
Nuclear fuel, net of accumulated amortization of $118,074 and $126,157	99,490	100,119
Total property, plant and equipment	17,979,860	16,800,254
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trusts (Notes 12 and 18)	1,201,246	1,073,410
Other special use funds (Notes 12 and 18)	362,781	347,231
Assets from risk management activities (Note 15)	0	44,394
Other assets	43,625	43,344
Total investments and other assets	1,607,652	1,508,379
CURRENT ASSETS
Cash and cash equivalents	4,549	4,042
Customer and other receivables	510,296	448,880
Accrued unbilled revenues	167,553	164,764
Allowance for doubtful accounts (Note 2)	(22,433)	(23,778)
Materials and supplies (at average cost)	444,344	410,481
Fossil fuel (at average cost)	49,203	40,155
Income tax receivable (Note 4)	0	1,102
Assets from risk management activities (Note 15)	6,808	87,704
Deferred fuel and purchased power regulatory asset (Note 3)	463,195	460,561
Other regulatory assets (Note 3)	162,562	78,318
Other current assets	64,311	50,043
Total current assets	1,850,388	1,722,272
DEFERRED DEBITS
Regulatory assets (Notes 1, 3, 4 and 7)	1,390,279	1,283,221
Operating lease right-of-use assets (Note 8)	1,308,611	796,544
Assets for pension and other postretirement benefits (Note 7)	316,606	389,142
Other	63,059	44,040
Total deferred debits	3,078,555	2,512,947
TOTAL ASSETS	24,516,455	22,543,852
CAPITALIZATION
Common stock	178,162	178,162
Additional paid-in capital	3,321,696	3,171,696
Retained earnings	3,759,299	3,607,464
Accumulated other comprehensive loss (Note 19)	(17,219)	(15,596)
Total shareholders’ equity	7,241,938	6,941,726
Noncontrolling interests (Note 17)	107,198	111,229
Total equity	7,349,136	7,052,955
Long-term debt less current maturities (Note 6)	7,041,891	6,793,529
Total capitalization	14,391,027	13,846,484
CURRENT LIABILITIES
Short-term borrowings (Note 5)	532,850	325,000
Accounts payable	433,229	417,732
Accrued taxes	162,288	156,746
Accrued interest	72,548	60,518
Common dividends payable	99,800	97,900
Customer deposits	42,037	41,769
Liabilities from risk management activities (Note 15)	80,913	37,697
Liabilities for asset retirements (Note 11)	28,550	12,232
Operating lease liabilities (Note 8)	67,608	104,728
Regulatory liabilities (Note 3)	209,923	271,575
Other current liabilities	211,773	144,733
Total current liabilities	2,191,519	1,670,630
DEFERRED CREDITS AND OTHER
Deferred income taxes (Note 4)	2,431,697	2,385,647
Regulatory liabilities (Notes 1, 3, 4 and 7)	1,965,865	2,061,776
Liabilities for asset retirements (Note 11)	937,451	785,530
Liabilities for pension benefits (Note 7)	106,215	108,068
Customer advances	533,580	422,103
Coal mine reclamation	184,007	179,255
Deferred investment tax credit	257,743	180,677
Unrecognized tax benefits (Note 4)	33,861	38,658
Operating lease liabilities (Note 8)	1,208,857	634,199
Other	231,658	226,985
Total deferred credits and other	7,933,909	7,026,738
COMMITMENTS AND CONTINGENCIES (Note 10)
TOTAL LIABILITIES AND EQUITY	24,516,455	22,543,852
Current maturities of long-term debt (Note 6)	250,000	0
Liabilities from risk management activities (Note 15)	$ 42,975	$ 3,840

APS - CONSOLIDATED BALANCE SH_2

APS - CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
PROPERTY, PLANT AND EQUIPMENT
Accumulated depreciation of Palo Verde sale leaseback	$ 264,624	$ 260,754
Accumulated amortization on intangible assets	885,505	817,961
Accumulated amortization on nuclear fuel	118,074	126,157
Arizona Public Service Company
PROPERTY, PLANT AND EQUIPMENT
Accumulated depreciation of Palo Verde sale leaseback	264,624	260,754
Accumulated amortization on intangible assets	884,371	816,827
Accumulated amortization on nuclear fuel	$ 118,074	$ 126,157

APS - CONSOLIDATED STATEMENTS_4

APS - CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 518,781	$ 500,826	$ 635,944
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	854,136	817,814	719,141
Deferred fuel and purchased power	(549,877)	(291,992)	(256,871)
Deferred fuel and purchased power amortization	547,243	219,579	44,557
Allowance for equity funds used during construction	(53,118)	(45,263)	(41,737)
Deferred income taxes	(24,310)	43,202	117,471
Deferred investment tax credit	77,065	(5,893)	(4,802)
Changes in current assets and liabilities:
Customer and other receivables	(61,983)	(63,869)	(72,559)
Accrued unbilled revenues	(2,789)	(30,784)	(1,783)
Materials, supplies and fossil fuel	(42,911)	(83,469)	(32,870)
Income tax receivable	13,754	(6,572)	(722)
Other current assets	(19,550)	76,089	(22,770)
Accounts payable	(75,623)	90,076	20,267
Accrued taxes	2,393	(4,205)	9,094
Other current liabilities	40,510	(1,856)	(51,736)
Change in long-term regulatory assets	(53,112)	(12,432)	17,012
Change in long-term regulatory liabilities	28,495	(332,470)	57,549
Change in other long-term assets	(195,598)	159,030	(345,470)
Change in operating lease assets	90,525	105,359	116,009
Change in other long-term liabilities	63,080	170,359	78,219
Change in operating lease liabilities	(65,779)	(103,671)	(108,365)
Net cash provided by operating activities	1,207,697	1,241,441	860,014
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,846,370)	(1,707,490)	(1,473,475)
Contributions in aid of construction	180,866	137,436	105,654
Allowance for borrowed funds used during construction	(43,564)	(28,030)	(21,052)
Proceeds from nuclear decommissioning trust sales and other special use funds	1,679,722	1,207,713	1,720,966
Investment in nuclear decommissioning trust and other special use funds	(1,681,845)	(1,212,063)	(1,725,480)
Other	(6,458)	(15,612)	6,458
Net cash used for investing activities	(1,694,249)	(1,618,046)	(1,386,929)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	689,349	875,537	746,999
Short-term borrowings and (repayments) — net	241,900	48,720	142,000
Dividends paid on common stock	(386,486)	(378,881)	(369,478)
Noncontrolling interests	(21,255)	(21,255)	(21,255)
Net cash provided by financing activities	486,675	371,468	476,916
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	123	(5,137)	(49,999)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	4,832	9,969	59,968
CASH AND CASH EQUIVALENTS AT END OF YEAR	4,955	4,832	9,969
Arizona Public Service Company
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	564,561	542,153	649,503
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization including nuclear fuel	854,051	817,729	719,039
Deferred fuel and purchased power	(549,877)	(291,992)	(256,871)
Deferred fuel and purchased power amortization	547,243	219,579	44,557
Allowance for equity funds used during construction	(53,118)	(45,263)	(41,737)
Deferred income taxes	(10,314)	(6,817)	128,852
Deferred investment tax credit	77,065	(5,893)	(4,802)
Changes in current assets and liabilities:
Customer and other receivables	(62,716)	(60,930)	(72,101)
Accrued unbilled revenues	(2,789)	(30,784)	(1,783)
Materials, supplies and fossil fuel	(42,911)	(83,469)	(32,870)
Income tax receivable	1,102	9,654	(10,756)
Other current assets	(20,243)	59,970	(25,637)
Accounts payable	(70,622)	79,492	23,510
Accrued taxes	5,542	4,734	3,042
Other current liabilities	62,212	1,190	(61,297)
Change in long-term regulatory assets	53,112	12,432	(17,012)
Change in long-term regulatory liabilities	28,495	(332,470)	57,549
Change in other long-term assets	(188,483)	170,587	(330,642)
Change in operating lease assets	90,234	105,058	115,850
Change in other long-term liabilities	58,574	168,503	87,376
Change in operating lease liabilities	(65,482)	(103,361)	(108,216)
Net cash provided by operating activities	1,275,636	1,230,102	865,554
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,825,585)	(1,655,051)	(1,471,795)
Contributions in aid of construction	180,866	137,436	105,654
Allowance for borrowed funds used during construction	(39,030)	(26,839)	(21,052)
Proceeds from nuclear decommissioning trust sales and other special use funds	1,679,722	1,207,713	1,720,966
Investment in nuclear decommissioning trust and other special use funds	(1,681,845)	(1,212,063)	(1,725,480)
Other	(1,397)	(727)	273
Net cash used for investing activities	(1,687,269)	(1,549,531)	(1,391,434)
CASH FLOWS FROM FINANCING ACTIVITIES
Issuance of long-term debt	496,025	524,852	446,999
Short-term borrowings and (repayments) — net	180,970	46,300	278,700
Dividends paid on common stock	(393,600)	(385,800)	(376,500)
Equity infusion from Pinnacle West	150,000	150,000	150,000
Noncontrolling interests	(21,255)	(21,255)	(21,255)
Net cash provided by financing activities	412,140	314,097	477,944
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	507	(5,332)	(47,936)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	4,042	9,374	57,310
CASH AND CASH EQUIVALENTS AT END OF YEAR	$ 4,549	$ 4,042	$ 9,374

APS - CONSOLIDATED STATEMENTS_5

APS - CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Arizona Public Service Company	Arizona Public Service Company Common Stock	Arizona Public Service Company Additional Paid-In Capital	Arizona Public Service Company Retained Earnings	Arizona Public Service Company Accumulated Other Comprehensive Income (Loss)	Arizona Public Service Company Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2020		112,760,051					71,264,947
Beginning balance at Dec. 31, 2020	$ 5,752,793	$ 2,677,482	$ 3,025,106	$ (62,796)	$ 119,290	$ 6,345,185	$ 178,162	$ 2,871,696	$ 3,216,955	$ (40,918)	$ 119,290
Increase (Decrease) in Shareholders' Equity
Equity infusion from Pinnacle West						150,000		150,000
Net income	635,944		618,720		17,224	649,503			632,279		17,224
Other comprehensive income	7,935			7,935		6,038				6,038
Dividends on common stock	(379,108)		(379,108)			(379,000)			(379,000)
Capital activities by noncontrolling interests	(21,255)				(21,255)	(21,255)					(21,255)
Other	2		1		1	2			1		1
Ending balance (in shares) at Dec. 31, 2021		113,014,528					71,264,947
Ending balance at Dec. 31, 2021	6,021,460	$ 2,702,743	3,264,719	(54,861)	115,260	6,750,473	$ 178,162	3,021,696	3,470,235	(34,880)	115,260
Increase (Decrease) in Shareholders' Equity
Equity infusion from Pinnacle West						150,000		150,000
Net income	500,826		483,602		17,224	542,153			524,929		17,224
Other comprehensive income	23,426			23,426		19,284				19,284
Dividends on common stock	(387,975)		(387,975)			(387,700)			(387,700)
Capital activities by noncontrolling interests	(21,255)				(21,255)	(21,255)					(21,255)
Other	$ 2	$ 1	1
Ending balance (in shares) at Dec. 31, 2022	113,247,189	113,247,189					71,264,947
Ending balance at Dec. 31, 2022	$ 6,159,876	$ 2,724,740	3,360,347	(31,435)	111,229	7,052,955	$ 178,162	3,171,696	3,607,464	(15,596)	111,229
Increase (Decrease) in Shareholders' Equity
Equity infusion from Pinnacle West						150,000		150,000
Net income	518,781		501,557		17,224	564,561			547,337		17,224
Other comprehensive income	(1,709)			(1,709)		(1,623)				(1,623)
Dividends on common stock	(395,585)		(395,585)			(395,500)			(395,500)
Capital activities by noncontrolling interests	(21,255)				(21,255)	(21,255)					(21,255)
Other	$ (3)		(2)			(2)			(2)		0
Ending balance (in shares) at Dec. 31, 2023	113,537,689	113,537,689					71,264,947
Ending balance at Dec. 31, 2023	$ 6,284,862	$ 2,752,676	$ 3,466,317	$ (33,144)	$ 107,198	$ 7,349,136	$ 178,162	$ 3,321,696	$ 3,759,299	$ (17,219)	$ 107,198

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Description of Business and Basis of Presentation Pinnacle West is a holding company that conducts business through its subsidiaries, APS, El Dorado and PNW Power. APS, our wholly-owned subsidiary, is a vertically-integrated electric utility that provides either retail or wholesale electric service to substantially all of the state of Arizona, with the major exceptions of about one-half of the Phoenix metropolitan area, the Tucson metropolitan area and Mohave County in northwestern Arizona. APS accounts for essentially all of our revenues and earnings and is expected to continue to do so. El Dorado is a wholly-owned subsidiary that invests in energy-related and Arizona community-based ventures. PNW Power is a wholly-owned subsidiary that was created in September 2023 to hold certain investments in wind and transmission joint projects. See Note 20 for more information on PNW Power. BCE was a Pinnacle West subsidiary that was formed in 2014. On August 4, 2023, Pinnacle West entered into a purchase and sale agreement pursuant to which all of our equity interest in BCE was sold. The sale was completed on January 12, 2024. See Note 20 for more information relating to the sale of BCE. Pinnacle West’s Consolidated Financial Statements include the accounts of Pinnacle West and our subsidiaries: APS, El Dorado, BCE and PNW Power. APS’s Consolidated Financial Statements include the accounts of APS and certain VIEs relating to the Palo Verde sale leaseback. Intercompany accounts and transactions between the consolidated companies have been eliminated. We consolidate Variable Interest Entities (each a “VIE”) for which we are the primary beneficiary. We determine whether we are the primary beneficiary of a VIE through a qualitative analysis that identifies which variable interest holder has the controlling financial interest in the VIE. In performing our primary beneficiary analysis, we consider all relevant facts and circumstances, including the design and activities of the VIE, the terms of the contracts the VIE has entered into, and which parties participated significantly in the design or redesign of the entity. We continually evaluate our primary beneficiary conclusions to determine if changes have occurred which would impact our primary beneficiary assessments. We have determined that APS is the primary beneficiary of certain VIE lessor trusts relating to the Palo Verde sale leaseback, and therefore APS consolidates these entities. See Note 17 for additional information. We have determined that Pinnacle West is the primary beneficiary of a captive insurance protected cell VIE. As of December 31, 2023, the captive cell’s activities are insignificant to our consolidated financial statements. Our consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments, except as otherwise disclosed in the notes) that we believe are necessary for the fair presentation of our financial position, results of operations and cash flows for the periods presented. Accounting Records and Use of Estimates Our accounting records are maintained in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. To conform with the current year’s disaggregated presentation of significant changes in assets and liabilities and the aggregation of less significant changes in assets and liabilities, we made certain reclassifications for the year ended December 31, 2022, within the operating activities section of our Consolidated Statements of Cash Flows. Regulatory Accounting APS is regulated by the ACC and the FERC. The accompanying financial statements reflect the rate-making policies of these commissions. As a result, we capitalize certain costs that would be included as expense in the current period by unregulated companies. Regulatory assets represent incurred costs that have been deferred because they are probable of future recovery in customer rates. Regulatory liabilities generally represent amounts collected in rates to recover costs expected to be incurred in the future or amounts collected in excess of costs incurred and are refundable to customers. Management judgments include continually assessing the likelihood of future recovery of regulatory assets and/or a disallowance of part of the cost of recently completed plant, by considering factors such as applicable regulatory environment changes and recent rate orders to other regulated entities in the same jurisdiction. This determination reflects the current political and regulatory climate in Arizona and is subject to change in the future. If future recovery of costs ceases to be probable, the assets would be written off as a charge in current period earnings. Management judgments also include assessing the impact of potential commission-ordered refunds to customers on regulatory liabilities. See Note 3 for additional information. Electric Revenues Revenues primarily consist of activities that are classified as revenues from contracts with customers. Our electric revenues generally represent a single performance obligation delivered over time. We have elected to apply the practical expedient that allows us to recognize revenue based on the amount to which we have a right to invoice for services performed. We derive electric revenues primarily from sales of electricity to our regulated retail customers. Revenues related to the sale of electricity are generally recognized when service is rendered or electricity is delivered to customers. Unbilled revenues are estimated by applying an average revenue/kWh by customer class to the number of estimated kWhs delivered but not billed. Differences historically between the actual and estimated unbilled revenues are immaterial. We exclude sales taxes and franchise fees on electric revenues from both revenue and taxes other than income taxes. Revenues from our regulated retail customers and non-derivative instruments are reported on a gross basis on Pinnacle West’s Consolidated Statements of Income. In the electricity business, some contracts to purchase electricity are netted against other contracts to sell electricity. This is called a “book-out” and usually occurs for contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow. We net these book-outs, which reduces both wholesale revenues and fuel and purchased power costs. Certain cost recovery mechanisms may qualify as alternative revenue programs. For alternative revenue programs that meet specified accounting criteria, we recognize revenues when the specific events permitting billing of the additional revenues have been completed. See Notes 2 and 3 for additional information. Allowance for Doubtful Accounts The allowance for doubtful accounts represents our best estimate of accounts receivable and accrued unbilled revenues that will ultimately be uncollectible due to credit loss risk. The allowance includes a write-off component that is calculated by applying an estimated write-off factor to retail electric revenues. The write-off factor used to estimate uncollectible accounts is based upon consideration of historical collections experience, the current and forecasted economic environment, changes to our collection policies, and management’s best estimate of future collections success. See Note 2. Property, Plant and Equipment Utility plant is the term we use to describe the business property and equipment that supports electric service, consisting primarily of generation, transmission, and distribution facilities. We report utility plant at its original cost, which includes: • material and labor; • contractor costs; • capitalized leases; • construction overhead costs (where applicable); and • AFUDC. Pinnacle West’s property, plant and equipment included in the December 31, 2023, and 2022 Consolidated Balance Sheets is composed of the following (dollars in thousands): Property, Plant and Equipment: 2023 2022 Generation $ 10,446,291 $ 9,563,145 Transmission 3,773,253 3,589,456 Distribution 8,448,293 7,951,867 General plant 1,543,330 1,347,678 Plant in service and held for future use 24,211,167 22,452,146 Accumulated depreciation and amortization (8,408,040) (7,929,878) Net 15,803,127 14,522,268 Construction work in progress 1,724,004 1,882,791 Palo Verde sale leaseback, net of accumulated depreciation 86,426 90,296 Intangible assets, net of accumulated amortization 267,110 258,880 Nuclear fuel, net of accumulated amortization 99,490 100,119 Total property, plant and equipment $ 17,980,157 $ 16,854,354 Property, plant and equipment balances and classes for APS are not materially different than Pinnacle West. We expense the costs of plant outages, major maintenance and routine maintenance as incurred. We charge retired utility plant to accumulated depreciation. Liabilities associated with the retirement of tangible long-lived assets are recognized at fair value as incurred and capitalized as part of the related tangible long-lived assets. Accretion of the liability due to the passage of time is an operating expense, and the capitalized cost is depreciated over the useful life of the long-lived asset. See Note 11 for additional information. APS records a regulatory liability for the excess that has been recovered in regulated rates over the amount calculated in accordance with guidance on accounting for AROs. APS believes it is probable it will recover in regulated rates, the costs calculated in accordance with this accounting guidance. We record depreciation and amortization on utility plant on a straight-line basis over the remaining useful life of the related assets. The approximate remaining average useful lives of our utility property at December 31, 2023, were as follows: • Steam generation — 11 years; • Nuclear plant — 25 years; • Other generation — 18 years; • Transmission — 38 years; • Distribution — 33 years; and • General plant — 7 years. Depreciation of utility property, plant and equipment is computed on a straight-line, remaining-life basis. Depreciation expense was $669 million in 2023, $632 million in 2022, and $575 million in 2021. For the years 2021 through 2023, the depreciation rates ranged from a low of 1.37% to a high of 12.15%. The weighted-average depreciation rate was 2.98% in 2023, 3.03% in 2022, and 2.87% in 2021. Asset Retirement Obligations APS has AROs for its Palo Verde nuclear facilities and certain other generation assets. The Palo Verde ARO primarily relates to final plant decommissioning. This obligation is based on the NRC’s requirements for disposal of radiated property or plant and agreements APS reached with the ACC for final decommissioning of the plant. The non-nuclear generation AROs primarily relate to requirements for removing portions of those plants at the end of the plant life or lease term and coal ash pond closures. Some of APS’s transmission and distribution assets have AROs because they are subject to right of way and easement agreements that require final removal. These agreements have a history of uninterrupted renewal that APS expects to continue. As a result, APS cannot reasonably estimate the fair value of the ARO related to such transmission and distribution assets. Additionally, APS has aquifer protection permits for some of its generation sites that require the closure of certain facilities at those sites. See Note 11 for further information on Asset Retirement Obligations. Allowance for Funds Used During Construction AFUDC represents the approximate net composite interest cost of borrowed funds and an allowed return on the equity funds used for construction of regulated utility plant. Both the debt and equity components of AFUDC are non-cash amounts within the Consolidated Statements of Income. Plant construction costs, including AFUDC, are recovered in authorized rates through depreciation when completed projects are placed into commercial operation. AFUDC was calculated by using a composite rate of 6.29% for 2023, 5.75% for 2022, and 6.75% for 2021. APS compounds AFUDC semi-annually and ceases to accrue AFUDC when construction work is completed and the property is placed in service. On June 30, 2020, FERC issued an order granting a waiver request related to the existing AFUDC rate calculation beginning March 1, 2020, through February 28, 2021. On February 23, 2021, this waiver was extended until September 30, 2021. On September 21, 2021, it was further extended until March 31, 2022. The order provided a simplified approach that companies may elect to implement in order to minimize the significant distorted effect on the AFUDC formula resulting from increased short-term debt financing during the COVID-19 pandemic. APS adopted this simplified approach to computing the AFUDC composite rate by using a simple average of the actual historical short-term debt balances for 2019, instead of current period short-term debt balances, and left all other aspects of the AFUDC formula composite rate calculation unchanged. This change impacted the AFUDC composite rate in 2021 and for the three-month period ended March 31, 2022. Furthermore, the change in the composite rate calculation did not impact our accounting treatment for these costs. The change did not have a material impact on our financial statements. Materials and Supplies APS values materials, supplies and fossil fuel inventory using a weighted-average cost method. APS materials, supplies and fossil fuel inventories are carried at the lower of weighted-average cost or net realizable value, unless evidence indicates that the weighted-average cost (even if in excess of market) will be recovered. Fair Value Measurements We apply recurring fair value measurements to cash equivalents, derivative instruments, investments held in the nuclear decommissioning trust and other special use funds. On an annual basis, we apply fair value measurements to plan assets held in our retirement and other benefits plans. Due to the short-term nature of short-term borrowings, the carrying values of these instruments approximate fair value. Fair value measurements may also be applied on a nonrecurring basis to other assets and liabilities in certain circumstances such as impairments. We also disclose fair value information for our long-term debt, which is carried at amortized cost. See Note 6 for additional information. Fair value is the price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market which we can access for the asset or liability in an orderly transaction between willing market participants on the measurement date. Inputs to fair value may include observable and unobservable data. We maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. We determine fair market value using observable inputs such as actively-quoted prices for identical instruments when available. When actively-quoted prices are not available for the identical instruments, we use other observable inputs, such as prices for similar instruments, other corroborative market information, or prices provided by other external sources. For options, long-term contracts, and other contracts for which observable price data are not available, we use models and other valuation methods, which may incorporate unobservable inputs to determine fair market value. The use of models and other valuation methods to determine fair market value often requires subjective and complex judgment. Actual results could differ from the results estimated through application of these methods. See Note 12 for additional information about fair value measurements. Derivative Accounting We are exposed to the impact of market fluctuations in the commodity price and transportation costs of electricity, natural gas, coal and in interest rates. We manage risks associated with market volatility by utilizing various physical and financial instruments including futures, forwards, options, and swaps. As part of our overall risk management program, we may use derivative instruments to hedge purchases and sales of electricity and natural gas as well as interest rate risk. The changes in market value of such contracts have a high correlation to price changes in the hedged transactions. We also enter into derivative instruments for economic hedging purposes. Contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow are netted, which reduces both revenues and fuel and purchased power expenses in our Consolidated Statements of Income, but does not impact our financial condition, net income, or cash flows. We account for our derivative contracts in accordance with derivatives and hedging guidance, which requires all derivatives not qualifying for a scope exception to be measured at fair value on the balance sheet as either assets or liabilities. Transactions with counterparties that have master netting arrangements are reported net on the balance sheet. See Note 15 for additional information about our derivative instruments. Loss Contingencies and Environmental Liabilities Pinnacle West and APS are involved in certain legal and environmental matters that arise in the normal course of business. Contingent losses and environmental liabilities are recorded when it is determined that it is probable that a loss has occurred, and the amount of the loss can be reasonably estimated. When a range of the probable loss exists and no amount within the range is a better estimate than any other amount, Pinnacle West and APS record a loss contingency at the minimum amount in the range. Unless otherwise required by GAAP, legal fees are expensed as incurred. Retirement Plans and Other Postretirement Benefits Pinnacle West sponsors a qualified defined benefit and account balance pension plan for the employees of Pinnacle West and its subsidiaries, in addition to a non-qualified pension plan. We also sponsor another postretirement benefit plan for the employees of Pinnacle West and its subsidiaries that provides medical and life insurance benefits to retired employees. Pension and other postretirement benefit expense are determined by actuarial valuations, based on assumptions that are evaluated annually. See Note 7 for additional information on pension and other postretirement benefits. Nuclear Fuel APS amortizes nuclear fuel by using the unit-of-production method. The unit-of-production method is based on actual physical usage. APS divides the cost of the fuel by the estimated number of thermal units it expects to produce with that fuel. APS then multiplies that rate by the number of thermal units produced within the current period. This calculation determines the current period nuclear fuel expense. APS also charges nuclear fuel expense for the interim storage and permanent disposal of spent nuclear fuel. The DOE is responsible for the permanent disposal of spent nuclear fuel and charged APS $0.001 per kWh of nuclear generation through May 2014, at which point the DOE reduced the fee to zero. In accordance with a settlement agreement with the DOE in August 2014 for interim storage, we accrued a receivable and an offsetting regulatory liability through the settlement period ended December of 2023. See Note 10 for information on spent nuclear fuel disposal costs. Income Taxes Income taxes are provided using the asset and liability approach prescribed by guidance relating to accounting for income taxes and are based on currently enacted tax rates. We file our federal income tax return on a consolidated basis, and we file our state income tax returns on a consolidated or unitary basis. In accordance with our intercompany tax sharing agreement, federal and state income taxes are allocated to each first-tier subsidiary as though each first-tier subsidiary filed a separate income tax return. Any difference between that method and the consolidated (and unitary) income tax liability is attributed to the parent company. The income tax accounts reflect the tax and interest associated with management’s estimate of the largest amount of tax benefit that is greater than 50% likely of being realized upon settlement for all known and measurable tax exposures. See Note 4 for additional discussion. Cash and Cash Equivalents We consider cash equivalents to be highly liquid investments with a remaining maturity of three months or less at acquisition. The following table summarizes supplemental Pinnacle West cash flow information for each of the last three years (dollars in thousands): Year ended December 31, 2023 2022 2021 Cash paid during the period for: Income taxes, net of refunds $ 8,788 $ 46,227 $ 229 Interest, net of amounts capitalized 310,996 245,271 227,584 Significant non-cash investing and financing activities: Accrued capital expenditures $ 206,269 $ 114,999 $ 167,733 Dividends declared but not paid 99,813 97,895 95,988 BCE Sale non-cash consideration (Note 20) 28,262 — — The following table summarizes supplemental APS cash flow information for each of the last three years (dollars in thousands): Year ended December 31, 2023 2022 2021 Cash paid during the period for: Income taxes, net of refunds $ 21,734 $ 95,985 $ 19,783 Interest, net of amounts capitalized 267,261 227,159 217,749 Significant non-cash investing and financing activities: Accrued capital expenditures $ 206,269 $ 116,533 $ 167,657 Dividends declared but not paid 99,800 97,900 96,000 Intangible Assets We have no goodwill recorded and have separately disclosed other intangible assets, primarily APS’s software, on Pinnacle West’s Consolidated Balance Sheets. The intangible assets are amortized over their finite useful lives. Amortization expense was $90 million in 2023, $84 million in 2022, and $80 million in 2021. Estimated amortization expense on existing intangible assets over the next five years is $90 million in 2024, $75 million in 2025, $49 million in 2026, $23 million in 2027, and $11 million in 2028. At December 31, 2023, the weighted-average remaining amortization period for intangible assets was 5 years. Investments El Dorado holds investments in both debt and equity securities. Investments in debt securities are generally accounted for as held-to-maturity and investments in equity securities are accounted for using either the equity method (if significant influence) or the measurement alternative for investments without readily determinable fair values (if less than 20% ownership and no significant influence). PNW Power holds investments in equity securities. Investments in equity securities are accounted for using either the equity method (if significant influence) or the measurement alternative for investments without readily determinable fair values (if less than 20% ownership and no significant influence). Our investments in the nuclear decommissioning trusts, coal reclamation escrow accounts and active union employee medical account, are accounted for in accordance with guidance on accounting for investments in debt and equity securities. See Notes 12 and 18 for more information on these investments. Leases We determine if an agreement is a lease at contract inception. A lease is defined as a contract, or part of a contract, that conveys the right to control the use of an identified asset for a period of time in exchange for consideration. To control the use of an identified asset an entity must have both a right to obtain substantially all of the benefits from the use of the asset and the right to direct the use of the asset. If we determine an agreement is a lease, and we are the lessee, we recognize a right-of-use lease asset and a lease liability at the lease commencement date. Lease liabilities are recognized based on the present value of the fixed lease payments over the lease term. To present value lease liabilities we use the implicit rate in the lease if the information is readily available, otherwise we use our incremental borrowing rate determined at lease commencement. Our incremental borrowing rate is based on the rate of interest we would have to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. When measuring right-of-use assets and lease liabilities we exclude variable lease payments, other than those that depend on an index or rate or are in-substance fixed payments. For short-term leases with terms of 12 months or less, we do not recognize a right-of-use lease asset or lease liability. We recognize operating lease expense using a straight-line pattern over the periods of use. APS enters into purchased power contracts that may contain leases. This occurs when a purchased power agreement designates a specific power plant or facility, APS obtains substantially all of the economic benefits from the use of the facility and has the right to direct the use of the facility. Purchased power lease contracts may also include energy storage facilities. Lease costs relating to purchased power lease contracts are reported in fuel and purchased power on the Consolidated Statements of Income and are subject to recovery under the PSA or RES. See Note 3 . We also may enter into lease agreements related to vehicles, office space, land, and other equipment. See Note 8 for information on our lease agreements. Business Segments Pinnacle West’s reportable business segment is our regulated electricity segment, which consists of traditional regulated retail and wholesale electricity businesses (primarily electricity service to Native Load customers) and related activities and includes electricity generation, transmission, and distribution. All other segment activities are insignificant. Preferred Stock At December 31, 2023, Pinnacle West had 10 million shares of serial preferred stock authorized with no par value, none of which was outstanding, and APS had 15,535,000 shares of various types of preferred stock authorized with $25, $50, and $100 par values, none of which was outstanding.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Sources of Revenue The following table provides detail of Pinnacle West’s consolidated revenue disaggregated by revenue sources (dollars in thousands): Year Ended December 31, 2023 2022 2021 Retail Electric Service Residential $ 2,289,196 $ 2,046,111 $ 1,913,324 Non-Residential 2,048,416 1,767,616 1,586,940 Wholesale Energy Sales 208,985 383,126 187,640 Transmission Services for Others 138,631 116,628 99,285 Other Sources 10,763 10,904 16,646 Total Operating Revenues $ 4,695,991 $ 4,324,385 $ 3,803,835 Retail Electric Revenue. All of Pinnacle West’s retail electric revenue is generated by APS. Retail electric revenue is generated by the sale of electricity to our regulated customers within the authorized service territory at tariff rates approved by the ACC and based on customer usage. Revenues related to the sale of electricity are generally recognized when service is rendered, or electricity is delivered to customers. The billing of electricity sales to individual customers is based on the reading of their meters. We obtain customers’ meter data on a systematic basis throughout the month, and generally bill customers within a month from when service was provided. Customers are generally required to pay for services within 21 days of when the services are billed. See “Allowance for Doubtful Accounts” discussion below for additional details regarding payment terms. Wholesale Energy Sales and Transmission Services for Others. Revenues from wholesale energy sales and transmission services for others represent energy and transmission sales to wholesale customers. These activities primarily consist of managing fuel and purchased power risks in connection with the cost of serving our retail customers’ energy requirements. We may also sell into the wholesale markets generation that is not needed for APS’s retail load. Our wholesale activities and tariff rates are regulated by FERC. Revenue Activities Our revenues primarily consist of activities that are classified as revenues from contracts with customers. We derive our revenues from contracts with customers primarily from sales of electricity to our regulated retail customers. Revenues from contracts with customers also include wholesale and transmission activities. Our revenues from contracts with customers for the years ended December 31, 2023, 2022 and 2021 were $4,651 million, $4,302 million, and $3,760 million, respectively. We have certain revenues that do not meet the specific accounting criteria to be classified as revenues from contracts with customers. For the years ended December 31, 2023, 2022 and 2021, our revenues that do not qualify as revenue from contracts with customers were $45 million, $22 million and $44 million, respectively. This amount includes revenues related to certain regulatory cost recovery mechanisms that are considered alternative revenue programs. We recognize revenue associated with alternative revenue programs when specific events permitting recognition are completed. Certain amounts associated with alternative revenue programs will subsequently be billed to customers; however, we do not reclassify billed amounts into revenue from contracts with customers. See Note 3 for a discussion of our regulatory cost recovery mechanisms. Contract Assets and Liabilities from Contracts with Customers There were no material contract assets, contract liabilities, or deferred contract costs recorded on the Consolidated Balance Sheets as of December 31, 2023 and December 31, 2022. Allowance for Doubtful Accounts The allowance for doubtful accounts represents our best estimate of accounts receivable and accrued unbilled revenues that will ultimately be uncollectible due to credit loss risk. The allowance includes a write-off component that is calculated by applying an estimated write-off factor to retail electric revenues. The write-off factor used to estimate uncollectible accounts is based upon consideration of historical collections experience, the current and forecasted economic environment, changes to our collection policies, and management’s best estimate of future collections success. We continue to monitor the impacts of our disconnection policies, payment arrangements, among other considerations impacting our estimated write-off factor, and allowance for doubtful accounts. The following table provides a rollforward of Pinnacle West’s allowance for doubtful accounts (dollars in thousands): Year Ended December 31, 2023 2022 2021 Allowance for doubtful accounts, balance at beginning of period $ 23,778 $ 25,354 $ 19,782 Bad debt expense 23,399 17,006 22,251 Actual write-offs (24,744) (18,582) (16,679) Allowance for doubtful accounts, balance at end of period $ 22,433 $ 23,778 $ 25,354

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2023
Regulated Operations [Abstract]
Regulatory Matters	Regulatory Matters 2022 Retail Rate Case APS filed an application with the ACC on October 28, 2022 (the “2022 Rate Case”) seeking an increase in annual retail base rates on the date rates become effective (“Day 1”) of a net $460 million. This Day 1 net impact represents a total base revenue deficiency of $772 million offset by proposed adjustor transfers of cost recovery to annual retail rates and adjustor mechanism modifications. The average annual customer bill impact of APS’s request on Day 1 is an increase of 13.6%. The principal provisions of APS’s application were: • a test year comprised of twelve months ended June 30, 2022, adjusted as described below; • an original cost rate base of $10.5 billion, which approximates the ACC-jurisdictional portion of the book value of utility assets, net of accumulated depreciation and other credits; • the following proposed capital structure and costs of capital: Capital Structure Cost of Capital Long-term debt 48.07 % 3.85 % Common stock equity 51.93 % 10.25 % Weighted-average cost of capital 7.17 % • a 1% return on the increment of fair value rate base above APS’s original cost rate base, as provided for by Arizona law; • a rate of $0.038321 per kWh for the portion of APS’s retail base rates attributable to fuel and purchased power costs (“Base Fuel Rate”); • modification of its adjustment mechanisms including: ▪ eliminate the Environmental Improvement Surcharge (“EIS”) and collect costs through base rates, ▪ eliminate the Lost Fixed Cost Recovery (“LFCR”) mechanism and collect costs through base rates and the Demand Side Management Adjustment Charge (“DSMAC”), ▪ maintain as inactive the Tax Expense Adjustor Mechanism (“TEAM”), ▪ maintain the Transmission Cost Adjustment (“TCA”) mechanism, ▪ modify the performance incentive in the DSMAC, and ▪ modify the Renewable Energy Adjustment Charge (“REAC”) to include recovery of capital carrying costs of APS owned renewable and storage resources; • changes to its limited-income program, including a second tier to provide an additional discount for customers with greater need; and • twelve months of post-Test Year plant investments to reflect used and useful projects that will be placed into service prior to July 1, 2023. On June 5, 2023, and June 15, 2023, the ACC Staff, the Residential Utility Consumer Office (“RUCO”) and other intervenors filed their initial written testimony with the ACC. The ACC Staff recommends, among other things, (i) a $251 million revenue increase or, as an alternative, a $312 million revenue increase, (ii) a 9.6% return on equity, (iii) a 0.0% fair value increment or, as an alternative, a 0.75% fair value increment, and (iv) a continuation of a 12-month post-test year plant. RUCO recommends, among other things, (i) an $84.9 million revenue increase, (ii) an 8.2% return on equity or, as an alternative, an 8.7% return on equity if the ACC imputes a hypothetical capital structure with a 46% equity layer, (iii) a fair value increment of 0.0%, and (iv) a reduction of post-test year plant to six months. On July 12, 2023, APS filed rebuttal testimony addressing the ACC Staff and intervenors’ direct testimonies. The principal provisions of APS’s rebuttal testimony are: • reducing the revenue requirement increase to $383.1 million, which reduced the average annual customer bill impact to an increase of 11.3%; • maintaining a return on equity request of 10.25%; • reducing the increment of fair value rate base return to 0.5% from 1.0%; • maintaining a post-test year plant request of 12 months, plus the Four Corners Effluent Limitation Guidelines (“ELG”) project; • withdrawing the Payment Fee Removal Proposal (net reduction) which was originally requested in APS’s initial application; • maintaining the LFCR mechanism and DSMAC as separate adjustors; • increasing the Power Supply Adjustment (“PSA”) annual rate change limit from $0.004/kWh to $0.006/kWh; • proposing a new System Reliability Benefit (“SRB”) recovery mechanism; • maintaining the REAC in its current state; • maintaining adjustor base transfers and elimination of EIS; and • maintaining the request to recover Coal Community Transition (“CCT”) funding. On July 26, 2023, the ACC Staff, RUCO and other intervenors filed their surrebuttal testimony with the ACC. The ACC Staff adjusted their initial recommendations to, among other things, (i) a $281.9 million revenue increase, (ii) a 9.68% return on equity, (iii) a 0.5% fair value increment, (iv) a continuation of a 12-month post-test year plant that includes the Four Corners ELG project, and (v) support of an increase to the annual PSA increase limit to $0.006/kWh. RUCO maintained their direct position and also recommended further review of the PSA in a second phase of the 2022 Rate Case. On August 4, 2023, APS filed rejoinder testimony addressing the ACC Staff and intervenors’ surrebuttal testimonies. APS’s rejoinder testimony included final post-Test Year Plant values, reducing the revenue requirement increase to $377.7 million from $383.1 million, which reduced the average annual customer bill impact to an increase of 11.2%. All other major provisions from APS’s rebuttal testimony were maintained in its rejoinder testimony. On November 6, 2023, and November 21, 2023, APS and stakeholders filed briefs in the 2022 Rate Case. APS’s briefs included the reduction of the total revenue requirement increase to $376.2 million and a resulting average annual customer bill impact increase of 11.1%. All other major provisions from APS’s rejoinder testimony were maintained in its briefs. ACC Staff’s briefs included a proposed total revenue requirement increase from $281.9 million to $282.7 million and also included their support of APS’s SRB mechanism, contingent on increased stakeholder outreach. On January 25, 2024, an Administrative Law Judge issued a Recommended Opinion and Order in the 2022 Rate Case, as corrected on February 6, 2024 (the “2022 Rate Case ROO”). The 2022 Rate Case ROO recommended, among other things, (i) a $523.1 million increase in the annual base rate revenue requirement, (ii) a 9.55% return on equity, (iii) a 0.25% return on the increment of fair value rate base greater than original cost, (iv) an effective fair value rate of return of 4.36%, (v) 12 months of post-test year plant and the inclusion of the Four Corners ELG project, (vi) the approval of APS’s SRB proposal with certain procedural and other modifications, (vii) no additional CCT funding, (viii) a 5.0% return on the prepaid pension asset and a return of 5.35% on the OPEB liability, and (ix) no disallowances on APS’s coal contracts. The 2022 Rate Case ROO also recommended a number of changes to existing adjustors, including (i) the approval of modified DSM performance incentives and the requested DSM transfer to base rates, (ii) the retention of $1.9 million of REAC in the adjustor rather than base rates, (iii) a partial transfer of $27.1 million of LFCR funds to base rates, and (iv) the adoption of an increase in the annual PSA cap to $0.006/kWh. On February 22, 2024, the ACC approved a number of amendments to the 2022 Rate Case ROO that resulted in, among other things, (i) an approximately $491.7 million increase in the annual base revenue requirement, (ii) a 9.55% return on equity, (iii) a 0.25% return on the increment of fair value rate base greater than original cost, (iv) an effective fair value rate of return of 4.39%, (v) a return set at the Company’s weighted average cost of capital on the net prepaid pension asset and net other post-employment benefit liability in rate base, (vi) an adjustment to generation maintenance and outage expense to reflect a more reasonable level of test year costs, (vii) approval of the SRB mechanism with modifications to customer notifications, procedural timelines and the inclusion of any qualifying technology and fuel source bid received through an all-source request for proposal (“RFP”), and (viii) recovery of all DSM costs through the DSMAC rather than through base rates. The ACC’s decision results in an expected total net annual revenue increase for APS of approximately $253.4 million and a roughly 8% increase to the typical residential customer’s bill. The ACC is expected to issue the final order for the 2022 Rate Case in March 2024 with the new rates to become effective for all service rendered on or after March 8, 2024. 2019 Retail Rate Case On October 31, 2019, APS filed an application with the ACC for an annual increase in retail base rates (the “2019 Rate Case”). On August 2, 2021, an Administrative Law Judge issued a Recommended Opinion and Order in the 2019 Rate Case (the “2019 Rate Case ROO”) and issued corrections on September 10 and September 20, 2021. The 2019 Rate Case ROO recommended, among other things, (i) a $111 million decrease in annual revenue requirements, (ii) a return on equity of 9.16%, (iii) a 0.30% return on the increment of fair value rate base greater than original cost, with total fair value rate of return further adjusted to include a 0.03% reduction to return on equity resulting in an effective fair value rate of return of 4.95%, (iv) the nonrecovery of the deferral and rate base effects of the operating costs and construction of the Four Corners Power Plant (“Four Corners”) selective catalytic reduction (“SCR”) project (see “Four Corners SCR Cost Recovery” below for additional in formation), (v) the recovery of the deferral and rate base effects of the operating costs and construction of the Ocotillo modernization project, which includes a reduction in the return on the deferral, (vi) a 15% disallowance of annual amortization of the Navajo Generating Station (the “Navajo Plant”) regulatory asset recovery related to the closure of the Navajo Plant (see “Navajo Plant” below), (vii) the denial of the request to defer, until APS’s next general rate case, the increase or decrease in its Arizona property taxes attributable to tax rate changes, and (viii) a collaborative process to review and recommend revisions to APS’s adjustment mechanisms within 12 months after the date of the decision. The 2019 Rate Case ROO also recommended that the CCT plan related to the closure or future closure of coal-fired generation facilities include the following components: (i) $50 million that will be paid over 10 years to the Navajo Nation, (ii) $5 million that will be paid over five years to the Navajo County Communities surrounding Cholla Power Plant (“Cholla”), and (iii) $1.675 million that will be paid to the Hopi Tribe related to APS’s ownership interests in the Navajo Plant. These amounts would be recoverable from APS’s customers through the Arizona Renewable Energy Standard and Tariff (“RES”) adjustment mechanism. APS filed exceptions on September 13, 2021, regarding the disallowance of the SCR cost deferrals and plant investments that was recommended in the 2019 Rate Case ROO, among other issues. On October 6, 2021, and October 27, 2021, the ACC voted on various amendments to the 2019 Rate Case ROO that would result in, among other things, (i) a return on equity of 8.70%, which includes a 20-basis point penalty, (ii) the recovery of the deferral and rate base effects of the operating costs and construction of the Four Corners SCR project, with the exception of $215.5 million (see “Four Corners SCR Cost Recovery” below), (iii) that the CCT plan include the following components: (a) a payment of $1 million to the Hopi Tribe within 60 days of the 2019 Rate Case decision, (b) a payment of $10 million over three years to the Navajo Nation, (c) a payment of $0.5 million to the Navajo County communities within 60 days of the 2019 Rate Case decision, (d) up to $1.25 million for electrification of homes and businesses on the Hopi reservation, and (e) up to $1.25 million for the electrification of homes and businesses on the Navajo Nation reservation. These payments and expenditures are attributable to the future closures of Four Corners and Cholla, along with the prior closure of the Navajo Plant and all ordered payments and expenditures would be recoverable through rates, and (iv) a change in the residential on-peak time-of-use period from 3 p.m. to 8 p.m. to 4 p.m. to 7 p.m. Monday through Friday, excluding holidays. The 2019 Rate Case ROO, as amended, resulted in a total annual revenue decrease for APS of $4.8 million, excluding temporary payments and expenditures, under the CCT plan. On November 2, 2021, the ACC approved the 2019 Rate Case ROO, as amended. Consistent with the 2019 Rate Case decision, APS implemented the new rates effective as of December 1, 2021. In addition, the ACC ordered extensive compliance and reporting obligations. APS completed the implementation of the new on-peak hours for residential customers before the September 1, 2022, deadline. Additionally, consistent with the 2019 Rate Case decision, as of February 2024, APS completed the following payments that will be recoverable through rates related to the CCT: (i) $6.66 million to the Navajo Nation; (ii) $0.5 million to the Navajo County communities; and (iii) $1 million to the Hopi Tribe. Consistent with APS’s commitment to the impacted communities, APS has also completed the following payments: (i) $1 million to the Navajo Nation for CCT; (ii) $1.1 million to the Navajo County communities for CCT and economic development; and (iii) $1.25 million to the Hopi Tribe for CCT and economic development. The ACC has also authorized $1.25 million to be recovered through rates for electrification of homes and businesses on both the Navajo Nation and Hopi reservation. Expenditure of the recoverable funds for electrification of homes and businesses on the Navajo Nation and the Hopi reservations is contingent upon completion of a census of the unelectrified homes and businesses in each that are also within APS service territory. The census work was completed in November 2022 and disbursement of the $1.25 million for electrification of homes and businesses is planned to be finalized after discussions with the Navajo Nation and the Hopi Tribe are completed. On February 22, 2024, the ACC voted to not approve any further CCT funding. On November 24, 2021, APS filed an application for rehearing of the 2019 Rate Case with the ACC and the application was deemed denied on December 15, 2021, as the ACC did not act upon it. On December 17, 2021, APS filed its Notice of Direct Appeal at the Arizona Court of Appeals and a Petition for Special Action with the Arizona Supreme Court, requesting review of the disallowance of $215.5 million of Four Corners SCR plant investments and deferrals (see “Four Corners SCR Cost Recovery” below for additional information) and the 20-basis-point penalty reduction to the return on equity, among other things. On February 8, 2022, the Arizona Supreme Court declined to accept jurisdiction on APS’s Petition for Special Action. The Arizona Court of Appeals heard oral arguments on November 30, 2022. On March 6, 2023, the Court issued its opinion in this matter, affirming in part and reversing in part the ACC’s decision in the 2019 Rate Case. The Court vacated the 20-basis-point penalty included in the ACC’s allowed return on equity, as the Court determined the use of customer service metrics to justify the reduction exceeded the ACC’s ratemaking authority. Additionally, the Court vacated the disallowance of $215.5 million of APS’s Four Corners SCR investment. The Court remanded the issue to the ACC for further proceedings. The ACC requested an extension of the 30-day deadline to appeal the matter to the Arizona Supreme Court, and the Arizona Supreme Court granted the extension of the deadline to May 8, 2023. The ACC filed an appeal on May 8, 2023, and on May 15, 2023, requested a suspension of the case to allow for settlement discussions between the parties, which was approved by the Court. On June 14, 2023, APS and the ACC Legal Division filed a joint resolution with the ACC to allow recovery of the $215.5 million in costs related to the installation of the Four Corners SCR, a reversal of the 20-basis point reduction to APS’s return on equity from 8.9% to 8.7% as a result of the 2019 Rate Case Decision, and recovery of $59.6 million in revenue lost by APS between December of 2021 and June 20, 2023. On June 21, 2023, the ACC approved the joint resolution and proposals therein for recovery through the Court Resolution Surcharge (“CRS”) mechanism, which became effective on July 1, 2023. See “Court Resolution Surcharge” below for more information. On July 18, 2023, the Sierra Club filed an application for rehearing of the ACC’s decision. However, t he ACC did not act upon the application within 20 days, and it was therefore denied by operation of law. Subsequently, the Sierra Club did not file a notice of appeal to the Arizona Court of Appeals, and the time for an appeal has expired. Matter of Impact of the Closures of Fossil-Based Generation Plan on Impacted Communities On September 28, 2022, ACC Staff filed their staff report in the Matter of Impact of the Closures of Fossil-Based Generation Plan on Impacted Communities. APS and other interested parties filed comments on the report. On October 21, 2022, ACC Staff filed a revised report and proposed order. The revised report and proposed order recommended that funds for CCT shall not be collected from rate payers. On December 8, 2022, the ACC voted against ACC Staff’s proposed order, and on April 17, 2023, the ACC closed the docket. On February 22, 2024, the ACC voted to not approve any further CCT funding. Information Technology ACC Investigation On December 16, 2021, the ACC opened an investigation into various matters related to APS’s Information Technology department, including information about technology projects, costs, vendor management leadership and decision making. APS is cooperating with the investigation. APS cannot predict the outcome of this matter. Regulatory Lag Docket On January 5, 2023, the ACC opened a new docket to explore the possibility of modifications to the ACC’s historical test year rules. The ACC requested comments from utilities and interested parties on ways to reduce regulatory lag, including alternative ratemaking structures such as future test years and hybrid test years. APS filed comments on June 1, 2023. APS cannot predict the outcome of this matter. Cost Recovery Mechanisms APS has received regulatory decisions that allow for more timely recovery of certain costs outside of a general retail rate case through the following recovery mechanisms. See “2022 Retail Rate Case” above for modifications of adjustment mechanisms in the 2022 Rate Case. Renewable Energy Standard . In 2006, the ACC approved the RES. Under the RES, electric utilities that are regulated by the ACC must supply an increasing percentage of their retail electric energy sales from eligible renewable resources, including solar, wind, biomass, biogas and geothermal technologies. In order to achieve these requirements, the ACC allows APS to include a RES surcharge as part of customer bills to recover the approved amounts for use on renewable energy projects. Each year, APS is required to file a five-year implementation plan with the ACC and seek approval for funding the upcoming year’s RES budget. In 2015, the ACC revised the RES rules to allow the ACC to consider all available information, including the number of rooftop solar arrays in a utility’s service territory, to determine compliance with the RES. In June 2021, the ACC adopted a clean energy rules package which would require APS to meet certain clean energy standards and technology procurement mandates, obtain approval for its action plan included in its IRP, and seek cost recovery in a rate process. Since the adopted clean energy rules differed substantially from the original Recommended Order and Opinion, supplemental rulemaking procedures were required before the rules could become effective. On January 26, 2022, the ACC reversed its prior decision and declined to send the final draft energy rules through the rulemaking process. Instead, the ACC opened a new docket to consider all-source RFP requirements and the IRP process. See “Energy Modernization Plan” below for more information. On July 1, 2021, APS filed its 2022 RES Implementation Plan and proposed a budget of approximately $93.1 million. APS filed an amended 2022 RES Implementation Plan on December 9, 2021, with a proposed budget of $100.5 million. This budget included funding for programs to comply with the decision in the 2019 Rate Case, including the ACC authorizing spending $20 million to $30 million in capital costs for the continuation of the APS Solar Communities program each year for a period of three years from the effective date of the 2019 Rate Case decision. APS’s budget proposal supported existing approved projects and commitments and requested a waiver of the RES residential and non-residential distributed energy requirements for 2022. On May 18, 2022, the ACC approved the 2022 RES Implementation Plan, including an amendment requiring a stakeholder working group convene to develop a community solar program for the ACC’s consideration at a future date. On September 23, 2022, APS filed a community solar proposal in compliance with the ACC order that was informed by a stakeholder working group. APS proposed a small, pilot-scale program size of up to 140 MW that would be selected through a competitive RFP. The ACC has not yet ruled on the proposal. However, on November 10, 2022, the ACC approved a bifurcated community solar process, directing ACC Staff to develop a statewide policy through additional stakeholder involvement and establishing a separate evidentiary hearing to define other policy components. On March 23, 2023, the ACC approved a policy statement that included information on how statewide community solar and storage programs should be structured, their location, and inclusion in RFPs. The remainder of the community solar program policy components were deferred to the ACC’s Hearing Division so that a formal evidentiary hearing could be held to consider issues of substance related to community solar. APS cannot predict the outcomes of these future activities. On July 1, 2022, APS filed its 2023 RES Implementation Plan and proposed a budget of approximately $86.2 million, excluding any funding offsets. This budget contained funding for programs to comply with ACC-approved initiatives, including the 2019 Rate Case decision. APS’s budget proposal supported existing approved projects and commitments and requested a waiver of the RES residential and non-residential distributed energy requirements for 2022. On November 10, 2022, the ACC approved the 2023 RES Implementation Plan, including APS’s requested waiver of the distributed energy requirement for 2023. On June 30, 2023, APS filed its 2024 RES Implementation Plan and proposed a budget of approximately $95.1 million. APS’s budget proposal supports existing approved projects and commitments and requests a waiver of the RES renewable energy credit requirements to demonstrate compliance with the Annual Renewable Energy Requirement for 2023. The ACC has not yet ruled on the 2024 RES Implementation Plan. Demand Side Management Adjustor Charge . The ACC Electric Energy Efficiency Standards require APS to submit a DSM Plan annually for review and approval by the ACC. Verified energy savings from APS’s resource savings projects can be counted toward compliance with the Electric Energy Efficiency Standards; however, APS is not allowed to count savings from systems savings projects toward determination of the achievement of performance incentives, nor may APS include savings from these system savings projects in the calculation of its LFCR mechanism. See below for discussion of the LFCR. On December 17, 2021, APS filed its 2022 D SM Implementation Plan in accordance with an extension granted in 2021. The 2022 DSM Plan requested a budget of $78.4 million and represents an increase of approximately $14 million in DSM spending above 2021. On November 10, 2022, the ACC approved the 2022 DSM Implementation Plan, including a proposed performance incentive. On June 1, 2022, APS filed its 2023 Transportation Electrification Plan (“2023 TE Plan”). The 2023 TE Plan detailed APS’s efforts to grow and support transportation electrification in Arizona, including the Take Charge AZ Pilot Program and customer education and outreach related to transportation electrification. Subsequently, APS filed an amended 2023 TE Plan on November 30, 2022, that included a request for a $5 million budget. On December 12, 2023, the ACC approved the 2023 TE Plan without including the Take Charge AZ Program and its budget going forward, but allowed APS to complete projects already underway. Additionally, the ACC discontinued the residential EV SmartCharger rebate and approved modifications to the EV rate plan. On November 30, 2022, APS filed its 2023 DSM Implementation Plan, which requested a budget of $88 million. On May 31, 2023, APS filed an amended 2023 DSM Implementation Plan. The amended plan maintained the originally proposed budget of $88 million. Subsequent to filing the amended 2023 DSM Implementation Plan and prior to the ACC approving it, on November 30, 2023, APS filed its 2024 DSM Implementation Plan. The 2024 DSM Implementation Plan requested a total budget of $91.5 million and incorporated all elements of the amended 2023 DSM Implementation Plan as well as the 2024 TE Implementation Plan. The ACC has not yet ruled on the 2024 DSM Implementation Plan. APS cannot predict the outcome of this proceeding. Power Supply Adjustor Mechanism and Balance. The PSA provides for the adjustment of retail rates to reflect variations primarily in retail fuel and purchased power costs. The PSA is subject to specified parameters and procedures, including the following: • APS records deferrals for recovery or refund to the extent actual retail fuel and purchased power costs vary from the Base Fuel Rate; • an adjustment to the PSA rate is made annually each February 1 (unless otherwise approved by the ACC) and goes into effect automatically unless suspended by the ACC; • the PSA uses a forward-looking estimate of fuel and purchased power costs to set the annual PSA rate, which is reconciled to actual costs experienced for each PSA Year (February 1 through January 31) (see the following bullet point); • the PSA rate includes (a) a “forward component,” under which APS recovers or refunds differences between expected fuel and purchased power costs for the upcoming calendar year and those embedded in the Base Fuel Rate; (b) a “historical component,” under which differences between actual fuel and purchased power costs and those recovered or refunded through the combination of the Base Fuel Rate and the Forward Component are recovered during the next PSA Year; and (c) a “transition component,” under which APS may seek mid-year PSA changes due to large variances between actual fuel and purchased power costs and the combination of the Base Fuel Rate and the Forward Component; and • the PSA rate may not be increased or decreased more than $0.004 per kWh in a year without permission of the ACC. The following table shows the changes in the deferred fuel and purchased power regulatory asset for 2023 and 2022 (dollars in thousands): Twelve Months Ended 2023 2022 Beginning balance $ 460,561 $ 388,148 Deferred fuel and purchased power costs — current period 549,877 291,992 Amounts charged to customers (547,243) (219,579) Ending balance $ 463,195 $ 460,561 On November 30, 2021, APS filed its PSA rate for the PSA year beginning February 1, 2022. That rate was $0.007544 per kWh, which consisted of a forward component of $(0.004842) per kWh and a historical component of $0.012386 per kWh. The 2022 PSA rate was a $0.004 per kWh increase compared to the 2021 PSA year, which is the maximum permitted under the Plan of Administration for the PSA. These rates went into effect as filed on February 1, 2022. On April 1, 2022, the ACC filed a final report of its third-party audit findings regarding APS’s fuel and purchased power costs for the period January 2019 through January 2021. The report contains an in-depth review of APS’s fuel and purchased power contracts, its monthly fuel accounting activities, its forecasting and dispatching procedures, and its monthly PSA filings, among other fuel-related activities. The report finds that APS’s fuel processing accounting practices, dispatching procedures, and procedures for hedging activity are reasonable and appropriate. The report includes several recommendations for the ACC’s consideration, including review of current contracts, maintenance schedules, and certain changes and improvements to the schedules in APS’s monthly PSA filings. On December 27, 2022, ACC Staff filed a proposed order supporting adoption of the recommendations in the third-party audit report, and the ACC approved the proposed order on February 22, 2023. On November 30, 2022, APS filed its PSA rate for the PSA year beginning February 1, 2023. To address the growing under-collected PSA balance, APS also requested that one of three different options be adopted, including a temporary or permanent increase of the annual cap to $0.006 per kWh. On February 23, 2023, the ACC approved an overall PSA rate of $0.019074 per kWh, which consisted of a forward component of $(0.005527) per kWh, a historical component of $0.013071 per kWh and a transition component of $0.011530 per kWh, that will continue until further notice of the ACC. The rate became effective with the first billing cycle in March 2023 and is designed to bring the PSA balancing account to near-zero over a 24-month period. APS is also required to notify the ACC when the PSA balancing account approaches $0.5 million. In its 2022 Rate Case, APS proposed a permanent increase in the annual PSA adjustor rate cap, which would increase the amount the rate can change in any given year from the currently effective $0.004 per kWh to $0.006 per kWh. On February 22, 2024, the ACC voted to approve this request. On November 30, 2023, APS notified the ACC that it will be maintaining the current PSA rate of $0.019074 per kWh and an updated PSA adjustment schedule would not be filed at this time. In accordance with the PSA Plan of Administration, APS is required to seek ACC approval to recover costs related to third-party energy storage systems through its PSA adjustment mechanism. In 2023, nine energy storage PPAs and their respective costs have been approved for recovery through the PSA. In 2022, one energy storage PPA and its costs was approved for recovery through the PSA. In 2021, four energy storage PPAs and their respective costs were approved for recovery through the PSA. However, one energy storage PPA that was approved in 2021 was later terminated by APS due to project delays. Environmental Improvement Surcharge (“EIS”). The EIS permits APS to recover the capital carrying costs (rate of return, depreciation and taxes) plus incremental operations and maintenance expenses associated with environmental improvements made outside of a test year to comply with environmental standards set by federal, state, tribal, or local laws and regulations. A filing is made on or before February 1 each year for qualified environmental improvements since the prior rate case test year, and the new charge becomes effective April 1 unless suspended by the ACC. The EIS includes an overall cap of $0.0005 per kWh (approximately $13 million to $15 million per year). APS’s February 1, 2023, application requested an increase in the charge to $14.7 million, or $3.3 million over the prior-period charge. On March 10, 2023, APS filed an amended application requesting an EIS charge of $4.0 million, a decrease of $10.7 million from the February EIS request, and a decrease of $7.5 million from the prior-period charge. The revised 2023 EIS became effective with the first billing cycle in April 2023. On February 1, 2024, APS filed an application requesting an increase in the charge to $15.3 million, or $11.3 million over the prior-period charge. The 2022 Rate Case ROO has recommended eliminating the EIS. On February 22, 2024, the ACC approved the elimination of the EIS as recommended in the 2022 Rate Case ROO. With the elimination of the EIS, the surcharge will no longer be in effect. Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters . In July 2008, FERC approved a modification to APS’s Open Access Transmission Tariff to allow APS to move from fixed rates to a formula rate-setting methodology in order to more a

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Certain assets and liabilities are reported differently for income tax purposes than they are for financial statement purposes. The tax effect of these differences is recorded as deferred taxes. We calculate deferred taxes using currently enacted income tax rates. APS has recorded regulatory assets and regulatory liabilities related to income taxes on its Consolidated Balance Sheets in accordance with accounting guidance for regulated operations. The regulatory assets are for certain temporary differences, primarily the allowance for equity funds used during construction, investment tax credit (“ITC”) basis adjustment and tax expense of Medicare subsidy. The regulatory liabilities primarily relate to the change in income tax rates and deferred taxes resulting from ITCs. APS ITCs are deferred and are amortized over the life of the related property with such amortization applied as a credit to reduce current income tax expense in the Statements of Income. Net income associated with the Palo Verde sale leaseback VIEs is not subject to tax. As a result, there is no income tax expense associated with the VIEs recorded on the Pinnacle West Consolidated and APS Consolidated Statements of Income. See Note 17 for additional details related to the Palo Verde sale leaseback VIEs. The following is a tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year that are included in accrued taxes and unrecognized tax benefits (dollars in thousands): Pinnacle West Consolidated APS Consolidated 2023 2022 2021 2023 2022 2021 Total unrecognized tax benefits, January 1 $ 43,097 $ 45,086 $ 45,655 $ 43,097 $ 45,086 $ 45,655 Additions for tax positions of the current year 1,473 1,399 3,305 1,473 1,399 3,305 Additions for tax positions of prior years 419 2,069 1,449 419 2,069 1,449 Reductions for tax positions of prior years for: Changes in judgment 661 (3,495) (2,659) 661 (3,495) (2,659) Settlements with taxing authorities — — — — — — Lapses of applicable statute of limitations (1,376) (1,962) (2,664) (1,376) (1,962) (2,664) Total unrecognized tax benefits, December 31 $ 44,274 $ 43,097 $ 45,086 $ 44,274 $ 43,097 $ 45,086 Included in the balances of unrecognized tax benefits are the following tax positions that, if recognized, would decrease our effective tax rate (dollars in thousands): Pinnacle West Consolidated APS Consolidated 2023 2022 2021 2023 2022 2021 Tax positions, that if recognized, would decrease our effective tax rate $ 28,762 $ 28,246 $ 26,300 $ 28,762 $ 28,246 $ 26,300 As of the balance sheet date, the tax year ended December 31, 2020, and all subsequent tax years remain subject to examination by the IRS. With a few exceptions, we are no longer subject to state income tax examinations by tax authorities for years before 2019. We reflect interest and penalties, if any, on unrecognized tax benefits in the Pinnacle West Consolidated and APS Consolidated Statements of Income as income tax expense. The amount of interest expense or benefit recognized related to unrecognized tax benefits are as follows (dollars in thousands): Pinnacle West Consolidated APS Consolidated 2023 2022 2021 2023 2022 2021 Unrecognized tax benefit interest expense/(benefit) recognized $ 452 $ (139) $ (535) $ 452 $ (139) $ (535) Following are the total amount of accrued liabilities for interest recognized related to unrecognized benefits that could reverse and decrease our effective tax rate to the extent matters are settled favorably (dollars in thousands): Pinnacle West Consolidated APS Consolidated 2023 2022 2021 2023 2022 2021 Unrecognized tax benefit interest accrued $ 1,633 $ 1,181 $ 1,320 $ 1,633 $ 1,181 $ 1,320 Additionally, as of December 31, 2023, we have recognized less than $1 million of interest expense to be paid on the underpayment of income taxes for certain adjustments that we have filed, or will file, with the IRS. The components of income tax expense are as follows (dollars in thousands): Pinnacle West Consolidated APS Consolidated Year Ended December 31, Year Ended December 31, 2023 2022 2021 2023 2022 2021 Current: Federal $ 21,272 $ 35,617 $ (5,041) $ 26,405 $ 103,349 $ 1,514 State 2,854 1,950 2,458 1,027 161 (11) Total current 24,126 37,567 (2,583) 27,432 103,510 1,503 Deferred: Federal 37,273 23,693 95,327 44,922 (31,860) 101,175 State 15,513 13,567 17,342 21,830 19,150 22,875 Total deferred 52,786 37,260 112,669 66,752 (12,710) 124,050 Income tax expense/(benefit) $ 76,912 $ 74,827 $ 110,086 $ 94,184 $ 90,800 $ 125,553 The following chart compares pretax income at the 21% statutory federal income tax rate to income tax expense (dollars in thousands): Pinnacle West Consolidated APS Consolidated Year Ended December 31, Year Ended December 31, 2023 2022 2021 2023 2022 2021 Federal income tax expense at statutory rate $ 125,095 $ 120,887 $ 156,666 $ 138,337 $ 132,920 $ 162,762 Increases (reductions) in tax expense resulting from: State income tax net of federal income tax benefit 18,024 17,740 22,656 19,832 19,000 23,339 State income tax credits net of federal income tax benefit (3,513) (5,482) (7,015) (1,775) (3,744) (5,277) Net operating loss carryback tax benefit — — (5,915) — — — Excess deferred income taxes — Tax Cuts and Jobs Act (36,558) (36,241) (36,558) (36,558) (36,241) (36,558) Allowance for equity funds used during construction (Note 1) (5,964) (4,629) (4,180) (5,964) (4,629) (4,180) Palo Verde VIE noncontrolling interest (Note 17) (3,617) (3,617) (3,617) (3,617) (3,617) (3,617) Investment tax credit amortization (9,495) (5,608) (7,620) (9,495) (5,608) (7,620) Federal production tax credit (8,441) (3,146) (3,064) (5,460) — — Other federal income tax credits (3,453) (7,721) (3,912) (2,803) (7,721) (3,912) Other 4,834 2,644 2,645 1,687 440 616 Income tax expense/(benefit) $ 76,912 $ 74,827 $ 110,086 $ 94,184 $ 90,800 $ 125,553 The components of the net deferred income tax liability were as follows (dollars in thousands): Pinnacle West Consolidated APS Consolidated December 31, December 31, 2023 2022 2023 2022 DEFERRED TAX ASSETS Risk management activities $ 31,411 $ 8,826 $ 31,411 $ 8,826 Regulatory liabilities: Excess deferred income taxes — Tax Cuts and Jobs Act 283,161 295,014 283,161 295,014 Asset retirement obligation and removal costs 113,312 107,104 113,312 107,104 Unamortized investment tax credits 68,521 48,035 68,521 48,035 Other postretirement benefits 56,070 66,893 56,070 66,893 Other 39,857 62,915 39,857 62,915 Operating lease liabilities 316,067 184,030 315,670 182,663 Pension liabilities 33,294 33,674 29,918 30,436 Coal reclamation liabilities 45,505 44,312 45,505 44,312 Renewable energy incentives 17,261 19,948 17,261 19,948 Credit and loss carryforwards 43,940 37,647 3,031 13,654 Other 77,865 72,605 77,865 72,605 Total deferred tax assets 1,126,264 981,003 1,081,582 952,405 DEFERRED TAX LIABILITIES Plant-related (2,572,495) (2,518,164) (2,572,495) (2,518,164) Risk management activities (1,682) (32,648) (1,682) (32,648) Pension and other postretirement assets (78,853) (96,845) (78,297) (96,196) Other special use funds (56,550) (57,572) (56,550) (57,572) Operating lease right-of-use assets (316,067) (184,030) (315,670) (182,663) Regulatory assets: Allowance for equity funds used during construction (46,754) (44,405) (46,754) (44,405) Deferred fuel and purchased power (149,078) (114,232) (149,078) (114,232) Pension benefits (172,239) (157,629) (172,239) (157,629) Retired power plant costs (20,659) (24,397) (20,659) (24,397) Other (92,260) (103,023) (92,260) (103,023) Other (36,107) (32,479) (7,595) (7,123) Total deferred tax liabilities (3,542,744) (3,365,424) (3,513,279) (3,338,052) Deferred income taxes — net $ (2,416,480) $ (2,384,421) $ (2,431,697) $ (2,385,647) As of December 31, 2023, Pinnacle West consolidated deferred tax assets for credit and loss carryforwards relate to federal and state credit carryforwards, net of federal benefit, of $56 million, which first begin to expire in 2025. Pinnacle West consolidated credit and loss carryforwards amount above has been reduced by $12 million of unrecognized tax benefits. As of December 31, 2023, APS consolidated deferred tax assets for credit and loss carryforwards relate to federal and state credit carryforwards, net of federal benefit, of $15 million, which first begin to expire in 2028. APS consolidated credit and loss carryforwards amount above has been reduced by $12 million of unrecognized tax benefits.

Lines of Credit and Short-Term

Lines of Credit and Short-Term Borrowings	12 Months Ended
	Dec. 31, 2023
Lines of Credit and Short-Term Borrowings
Lines of Credit and Short-Term Borrowings	Lines of Credit and Short-Term Borrowings Pinnacle West and APS maintain committed revolving credit facilities in order to enhance liquidity and provide credit support for their commercial paper programs, to refinance indebtedness, and for other general corporate purposes. The table below presents the consolidated credit facilities and the amounts available and outstanding (dollars in thousands): December 31, 2023 December 31, 2022 Pinnacle West APS Total Pinnacle West APS Total Commitments under Credit Facilities $ 200,000 $ 1,250,000 $ 1,450,000 $ 200,000 $ 1,000,000 $ 1,200,000 Outstanding short-term borrowings (76,650) (532,850) (609,500) (15,720) (325,000) (340,720) Amount of Credit Facilities Available $ 123,350 $ 717,150 $ 840,500 $ 184,280 $ 675,000 $ 859,280 Weighted-Average Commitment Fees 0.170% 0.120% 0.175% 0.125% Pinnacle West On April 10, 2023, Pinnacle West replaced its $200 million revolving credit facility that would have matured on May 28, 2026, with a new $200 million revolving credit facility that matures on April 10, 2028. Pinnacle West has the option to increase the amount of the facility up to a total of $300 million upon the satisfaction of certain conditions and with the consent of the lenders. Interest rates are based on Pinnacle West’s senior unsecured debt credit ratings and the agreement includes a sustainability-linked pricing metric which permits an interest rate reduction or increase by meeting or missing targets related to specific environmental and employee health and safety sustainability objectives. The facility is available to support Pinnacle West’s general corporate purposes, including support for Pinnacle West’s $200 million commercial paper program, for bank borrowings or for issuances of letters of credit. At December 31, 2023, Pinnacle West had no outstanding borrowings under its revolving credit facility, no letters of credit outstanding under t he credit facility, and $77 million of outstanding commercial paper borrowings. The weighted-average interest rate for the outstanding borrowings on December 31, 2023, was 5.47%. APS On April 10, 2023, APS replaced its two $500 million revolving credit facilities that would have matured on May 28, 2026, with a new $1.25 billion revolving credit facility that matures on April 10, 2028. APS has the option to increase the amount of the facility up to a maximum of $400 million, for a total of $1.65 billion, upon the satisfaction of certain conditions and with the consent of the lenders. Interest rates are based on APS’s senior unsecured debt credit ratings and the agreement includes a sustainability-linked pricing metric which permits an interest rate reduction or increase by meeting or missing targets related to specific environmental and employee health and safety sustainability objectives. The facility is available to support APS’s general corporate purposes, including support for APS’s commercial paper program, which was incr eased from $750 million to $1 billion on April 10, 2023, for bank borrowings or for issuances of letters of credit. At December 31, 2023, APS had no outstanding borrowings under its revolving credit facility, no letters of credit outstanding under the credit facility, and $533 million of outstanding commercial paper borrowings. The weighted-average interest rate for the outstanding borrowings on December 31, 2023, was 5.46%. On December 12, 2023, APS entered into an agreement with a new 364-day $350 million term loan facility that matures on December 10, 2024. Borrowings under the facility bear interest at SOFR plus 1.0% per annum. On February 9, 2024, APS drew the full amount of $350 million. See “Financial Assurances” in Note 10 for a discussion of other outst anding letters of credit. Debt Provisions On December 15, 2022, the ACC issued a financing order that, among other things, reaffirmed APS’s short-term debt authorization equal to the sum of (i) 7% of APS’s capitaliza tion, and (ii) $500 million (which is required to be used for costs relating to purchases of natural gas and power). See Note 6 for additional long-term debt provisions.

Long-Term Debt and Liquidity Ma

Long-Term Debt and Liquidity Matters	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Long-Term Debt and Liquidity Matters	Long-Term Debt and Liquidity Matters All of Pinnacle West’s and APS’s debt is unsecured. The following table presents the components of long-term debt on the Consolidated Balance Sheets outstanding (dollars in thousands): Maturity Interest December 31, Dates (a) Rates 2023 2022 APS Pollution control bonds: Variable 2029 (b) $ 163,975 $ 163,975 Total pollution control bonds 163,975 163,975 Senior unsecured notes 2024-2050 2.20%-6.88% 7,180,000 6,680,000 Unamortized discount (14,197) (14,548) Unamortized premium 11,162 12,368 Unamortized debt issuance cost (49,049) (48,266) Total APS long-term debt 7,291,891 6,793,529 Less current maturities 250,000 — Total APS long-term debt less current maturities 7,041,891 6,793,529 BCE Los Alamitos equity bridge loan (d) (d) — 27,575 Los Alamitos construction facility (d) (d) — 23,110 Unamortized debt issuance cost — (135) Total BCE long-term debt — 50,550 Less current maturities — 50,685 Total BCE long-term debt less current maturities — (135) Pinnacle West Senior unsecured notes 2025 1.30% 500,000 500,000 Term loans 2024 (c) 625,000 450,000 Unamortized discount (15) (25) Unamortized debt issuance cost (1,254) (2,083) Total Pinnacle West long-term debt 1,123,731 947,892 Less current maturities 625,000 — Total Pinnacle West long-term debt less current maturities 498,731 947,892 TOTAL LONG-TERM DEBT LESS CURRENT MATURITIES $ 7,540,622 $ 7,741,286 (a) This schedule does not reflect the timing of redemptions that may occur prior to maturities. (b) The weighted-average interest rate for the variable rate pollution control bonds was 4.11% at December 31, 2023, and 3.96% at December 31, 2022. (c) The weighted-average interest rate was 6.20% at December 31, 2023, and 5.10% at December 31, 2022. See additional details below. (d) On August 4, 2023, concurrent with the BCE Sale, the construction facility was transferred to Ameresco and the equity bridge loan was paid in full by Pinnacle West. See Note 20 and discussion below. The following table shows principal payments due on Pinnacle West’s and APS’s total long-term debt (dollars in thousands): Year Pinnacle West Consolidated APS Consolidated 2024 $ 875,000 $ 250,000 2025 800,000 300,000 2026 250,000 250,000 2027 300,000 300,000 2028 — — Thereafter 6,243,975 6,243,975 Total $ 8,468,975 $ 7,343,975 Debt Fair Value Our long-term debt fair value estimates are classified within Level 2 of the fair value hierarchy. The following table represents the estimated fair value of our long-term debt, including current maturities (dollars in thousands): As of As of Carrying Fair Value Carrying Fair Value Pinnacle West $ 1,123,731 $ 1,095,935 $ 947,892 $ 905,525 APS 7,291,891 6,459,718 6,793,529 5,629,491 BCE — — 50,550 50,685 Total $ 8,415,622 $ 7,555,653 $ 7,791,971 $ 6,585,701 Credit Facilities and Debt Issuances Pinnacle West On December 16, 2022, Pinnacle West entered into a $175 million term loan facility that matures December 16, 2024. The proceeds were received on January 6, 2023, and used for general corporate purposes. We recognized the term loan facility as long-term debt upon settlement on January 6, 2023. APS APS is currently authorized to receive up to $150 million annually in equity infusions from Pinnacle West without seeking ACC approval. On October 27, 2023, APS sought approval from the ACC to receive from Pinnacle West in 2024 up to an additional $500 million in equity infusions above the authorized limit of $150 million, and on January 9, 2024, the ACC approved the increased equity infusion limit for 2024. On January 6, 2023, Pinnacle West contributed $150 million into APS in the form of an equity infusion. APS used this contribution to repay short-term indebtedness. On June 30, 2023, APS issued $500 million of 5.55% unsecured senior notes that mature August 1, 2033. The net proceeds from the sale were used to repay short-term indebtedness consisting of commercial paper and for general corporate purposes. See “Lines of Credit and Short-Term Borrowings” in Note 5 and “Financial Assurances” in Note 10 for discussion of APS’s separate outstanding letters of credit. BCE On February 11, 2022, a special purpose subsidiary of BCE entered into a credit agreement to finance capital expenditures and related costs for the development of a 31 megawatt (“MW”) solar and 20 megawatt hour (“MWh”) battery storage project in Los Alamitos, California (“Los Alamitos”). The credit agreement consisted of an equity bridge loan facility, a non-recourse construction facility, a letter of credit facility, and a related interest rate swap. On August 4, 2023, Pinnacle West entered into a purchase and sale agreement with Ameresco, Inc. (“Ameresco”), pursuant to which we agreed to sell all our equity interest in BCE to Ameresco (the “BCE Sale”). See Note 20. As a part of the BCE Sale closing, the $36 million construction facility, the letter of credit facility, and the interest rate swap were transferred to Ameresco. On August 4, 2023, concurrent with the BCE Sale, Pinnacle West paid in full the outstanding $31 million equity bridge loan balance. As of December 31, 2023, there is no outstanding balance on our Consolidated Balance Sheets relating to this credit agreement. On April 18, 2023, and on December 29, 2023, Pinnacle West issued performance guarantees in connection with BCE’s Kūpono Solar investment project financing. BCE held an equity method investment relating to the Kūpono Solar project that was included in the BCE Sale relating to the stage of the BCE Sale that closed on January 12, 2024. The performance guarantees did not transfer in the BCE Sale, and Pinnacle West continues to retain these performance guarantees. See Note 10. Debt Provisions Pinnacle West’s and APS’s debt covenants related to their respective bank financing arrangements include maximum debt to capitalization ratios. Pinnacle West and APS comply with this covenant. For both Pinnacle West and APS, this covenant requires that the ratio of consolidated debt to total consolidated capitalization not exceed 65%. At December 31, 2023, the ratio was approximately 60% for Pinnacle West and 52% for APS. Failure to comply with such covenant levels would result in an event of default, which, generally speaking, would require the immediate repayment of the debt subject to the covenants and could cross-default other debt. See further discussion of “cross-default” provisions below. Neither Pinnacle West’s nor APS’s financing agreements contain “rating triggers” that would result in an acceleration of the required interest and principal payments in the event of a rating downgrade. However, our bank credit agreements contain a pricing grid in which the interest rates we pay for borrowings thereunder are determined by our current credit ratings. All of Pinnacle West’s loan agreements contain “cross-default” provisions that would result in defaults and the potential acceleration of payment under these loan agreements if Pinnacle West or APS were to default under certain other material agreements. All of APS’s bank agreements contain “cross-default” provisions that would result in defaults and the potential acceleration of payment under these bank agreements if APS were to default under certain other material agreements. Pinnacle West and APS do not have a material adverse change restriction for credit facility borrowings. Although provisions in APS’s articles of incorporation and ACC financing orders establish maximum amounts of preferred stock and debt that APS may issue, APS does not expect any of these provisions to limit its ability to meet its capital requirements. On December 15, 2022, the ACC issued a financing order approving APS’s application filed on April 6, 2022, requesting to increase the long-term debt limit from $7.5 billion to $8.0 billion and to exclude financing lease PPAs from the definition of long-term indebtedness for purposes of the ACC financing orders. See Note 5 for additional short-term debt provisions.

Retirement Plans and Other Post

Retirement Plans and Other Postretirement Benefits	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Retirement Plans and Other Postretirement Benefits	Retirement Plans and Other Postretirement Benefits Pinnacle West sponsors a qualified defined benefit and account balance pension plan (The Pinnacle West Capital Corporation Retirement Plan) and a non-qualified supplemental excess benefit retirement plan for the employees of Pinnacle West and its subsidiaries. All new employees participate in the account balance plan. Defined benefit plans specify the amount of benefits a plan participant is to receive using information about the participant. The pension plan covers nearly all employees. The supplemental excess benefit retirement plan covers officers of the Company and highly compensated employees designated for participation by the Board of Directors. Our employees do not contribute directly to the plans. We calculate the benefits based on age, years of service and pay. Pinnacle West also sponsors other postretirement benefit plans (Pinnacle West Capital Corporation Group Life and Medical Plan and Pinnacle West Capital Corporation Post-65 Retiree Health Reimbursement Arrangement “HRA”) for the employees of Pinnacle West and its subsidiaries. These plans provide medical and life insurance benefits to retired employees. Employees must retire to become eligible for these retirement benefits, which are based on years of service and age. For the medical insurance plan, retirees make contributions to cover a portion of the plan costs. For the life insurance plan, retirees do not make contributions. We retain the right to change or eliminate these benefits. Pinnacle West uses a December 31 measurement date each year for its pension and other postretirement benefit plans. The market-related value of our plan assets is their fair value at the measurement date. See Note 12 for further discussion of how fair values are determined. Due to subjective and complex judgments, which may be required in determining fair values, actual results could differ from the results estimated through the application of these methods. A significant portion of the changes in the actuarial gains and losses of our pension and postretirement plans is attributable to APS and are recoverable in rates. Accordingly, these changes are recorded as a regulatory asset or regulatory liability. Our retail rates provide for the inclusion of annual benefit expense, which allows for recovery or return of this regulatory asset/liability. S ee Note 3. The following table provides details of the plans’ net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction or billed to electric plant participants) (dollars in thousands): Pension Plans Other Benefits Plans 2023 2022 2021 2023 2022 2021 Service cost-benefits earned during the period $ 39,461 $ 55,473 $ 61,236 $ 8,567 $ 16,470 $ 17,796 Non-service costs (credits): Interest cost on benefit obligation 153,561 107,492 98,566 22,509 17,491 16,513 Expected return on plan assets (182,938) (185,775) (202,628) (43,486) (46,042) (41,444) Amortization of: Prior service credit (a) — — — (37,789) (37,789) (37,705) Net actuarial (gain)/loss 38,420 17,515 15,948 (9,614) (12,835) (10,093) Net periodic benefit cost/(benefit) $ 48,504 $ (5,295) $ (26,878) $ (59,813) $ (62,705) $ (54,933) Portion of cost/(benefit) charged to expense $ 27,029 $ (16,431) $ (32,743) $ (43,408) $ (45,042) $ (38,657) (a) Prior-service costs or credits reflect the impact of modifications to the pension or postretirement plan benefits. The impact of these modifications is amortized over a period which reflects the demographics of the impacted population. In 2014, Pinnacle West made changes to the postretirement benefits offered to Medicare eligible retirees which resulted in prior-service credits. We have been amortizing these prior-serviced credits since 2015 with the last full-year amortization occurring in 2024. The following table shows the plans’ changes in the benefit obligations and funded status (dollars in thousands): Pension Plans Other Benefits Plans 2023 2022 2023 2022 Change in Benefit Obligation Benefit obligation at January 1 $ 2,809,529 $ 3,716,824 $ 409,461 $ 591,841 Service cost 39,461 55,473 8,567 16,470 Interest cost 153,561 107,492 22,509 17,491 Benefit payments (210,737) (212,565) (30,784) (30,913) Actuarial (gain) loss 116,249 (857,695) 20,681 (185,428) Benefit obligation at December 31 2,908,063 2,809,529 430,434 409,461 Change in Plan Assets Fair value of plan assets at January 1 2,829,485 3,812,041 652,287 872,435 Actual return/(loss) on plan assets 199,098 (787,874) 67,317 (193,807) Benefit payments (193,034) (194,682) (23,110) (26,341) Fair value of plan assets at December 31 2,835,549 2,829,485 696,494 652,287 Funded/(Underfunded) Status at December 31 $ (72,514) $ 19,956 $ 266,060 $ 242,826 The following table shows information for pension plans with an accumulated obligation in excess of plan assets (dollars in thousands): As of December 31, 2023 2022 Accumulated benefit obligation $ 123,701 $ 126,759 Fair value of plan assets — — The Pinnacle West Capital Corporation Retirement Plan is more than 100% funded on an accumulated benefit obligation basis at December 31, 2023, and December 31, 2022, therefore, the only pension plan with an accumulated benefit obligation in excess of plan assets in 2023 and 2022 is a non-qualified supplemental excess benefit retirement plan. The following table shows information for pension plans with a projected benefit obligation in excess of plan assets (dollars in thousands): As of December 31, 2023 2022 Projected benefit obligation $ 129,891 $ 133,818 Fair value of plan assets — — The Pinnacle West Capital Corporation Retirement Plan is more than 100% funded on a projected benefit obligation basis at December 31, 2023, and December 31, 2022, therefore the only pension plan with a projected benefit obligation in excess of plan assets in 2023 and 2022 is a non-qualified supplemental excess benefit retirement plan. The following table shows the amounts recognized on the Consolidated Balance Sheets (dollars in thousands): Pension Plans Other Benefits Plans 2023 2022 2023 2022 Noncurrent asset $ 57,378 $ 153,773 $ 266,060 $ 242,826 Current liability (17,190) (17,531) — — Noncurrent liability (112,702) (116,286) — — Net amount recognized (funded status) $ (72,514) $ 19,956 $ 266,060 $ 242,826 The following table shows the details related to accumulated other comprehensive loss (gain) as of December 31, 2023, and 2022 (dollars in thousands): Pension Plans Other Benefits Plans 2023 2022 2023 2022 Net actuarial loss (gain) $ 743,003 $ 681,335 $ (188,630) $ (195,095) Prior service credit — — (39,054) (76,843) APS’s portion recorded as a regulatory (asset) liability (696,476) (637,656) 226,726 270,604 Income tax expense (benefit) (11,506) (10,797) 691 784 Accumulated other comprehensive loss (gain) $ 35,021 $ 32,882 $ (267) $ (550) The following table shows the weighted-average assumptions used for both the pension and other benefits to determine benefit obligations and net periodic benefit costs: Benefit Obligations Benefit Costs 2023 2022 2023 2022 2021 Discount rate – pension plans 5.21 % 5.56 % 5.56 % 2.92 % 2.53 % Discount rate – other benefits plans 5.23 % 5.58 % 5.58 % 2.98 % 2.63 % Rate of compensation increase 4.52 % 4.57 % 4.57 % 4.00 % 4.00 % Expected long-term return on plan assets - pension plans N/A N/A 6.70 % 5.00 % 5.30 % Expected long-term return on plan assets - other benefit plans N/A N/A 6.80 % 5.35 % 4.90 % Initial healthcare cost trend rate (pre-65 participants) 6.25 % 6.50 % 6.50 % 6.00 % 6.50 % Ultimate healthcare cost trend rate (pre-65 participants) 4.75 % 4.75 % 4.75 % 4.75 % 4.75 % Number of years to ultimate trend rate (pre-65 participants) 5 6 5 3 4 Initial and ultimate healthcare cost trend rate (post-65 participants) 2.00 % 2.00 % 2.00 % 2.00 % 2.00 % Interest crediting rate – cash balance pension plans 4.54 % 4.50 % 4.50 % 4.50 % 4.50 % In selecting the pretax expected long-term rate of return on plan assets, we consider past performance and economic forecasts for the types of investments held by the plan. For 2024, we are assuming a 6.90% long-term rate of return for pension assets and 7.00% (before tax) for other benefit assets, which we believe is reasonable given our asset allocation in relation to historical and expected performance. In selecting our healthcare trend rates, we consider past performance and forecasts of healthcare costs. Plan Assets The Board of Directors has delegated oversight of the pension and other postretirement benefit plans’ assets to an Investment Management Committee (“Committee”). The Committee has adopted investment policy statements (“IPS”) for the pension and the other postretirement benefit plans’ assets. The investment strategies for these plans include external management of plan assets. The overall strategy of the pension plan’s IPS is to achieve an adequate level of trust assets relative to the benefit obligations. To achieve this objective, the plan’s investment policy provides for mixes of investments including long-term fixed income assets and return-seeking assets. The target allocation between return-seeking and long-term fixed income assets is defined in the IPS. The plan’s funded status is reviewed on at least a monthly basis. Changes in the value of long-term fixed income assets, also known as liability-hedging assets, are intended to offset changes in the benefit obligations due to changes in interest rates. Long-term fixed income assets consist primarily of fixed income debt securities issued by the U.S. Treasury and other government agencies, U.S. Treasury futures contracts, and fixed income debt securities issued by corporations. Long-term fixed income assets may also include interest rate swaps, and other instruments. Return-seeking assets are intended to provide a reasonable long-term rate of investment return with a prudent level of volatility. Return-seeking assets are composed of U.S. equities, international equities, and alternative investments. International equities include investments in both developed and emerging markets. Alternative investments may include investments in real estate, private debt and various other strategies. The plan may also hold investments in return-seeking assets by holding securities in partnerships, common and collective trusts, and mutual funds. Based on the IPS, the target and actual allocation for the pension plan at December 31, 2023, are as follows: Target Allocation Actual Allocation Long-term fixed income assets 80 % 78 % Return-seeking assets 20 % 22 % Total 100 % 100 % The permissible range is within +/-5% of the target allocation shown in the above table, and also considers the plan’s funded status. The following table presents the additional target allocations, as a percent of total pension plan assets, for the return-seeking assets: Target Allocation Equities in US and other developed markets 12 % Equities in emerging markets 4 % Alternative investments 4 % Total 20 % The pension plan IPS does not provide for a specific mix of long-term fixed income assets but does expect the average credit quality of such assets to be investment grade. As of December 31, 2023, the asset allocation for other postretirement benefit plan assets is governed by the IPS for those plans, which provides for different asset allocation target mixes depending on the characteristics of the liability. The following table presents the actual allocations of the investment for the other postretirement benefit plan at December 31, 2023: Actual Allocation Long-term fixed income assets 62 % Return-seeking assets 38 % Total 100 % See Note 12 for a discussion on the fair value hierarchy and how fair value methodologies are applied. The plans invest directly in fixed income, U.S. Treasury Futures Contracts, and equity securities, in addition to investing indirectly in fixed income securities, equity securities and real estate through the use of mutual funds, partnerships and common and collective trusts. Equity securities held directly by the plans are valued using quoted active market prices from the published exchange on which the equity security trades and are classified as Level 1. U.S. Treasury Futures Contracts are valued using the quoted active market prices from the exchange on which they trade and are classified as Level 1. Fixed income securities issued by the U.S. Treasury held directly by the plans are valued using quoted active market prices and are classified as Level 1. Fixed income securities issued by corporations, municipalities, and other agencies are primarily valued using quoted inactive market prices, or quoted active market prices for similar securities, or by utilizing calculations which incorporate observable inputs such as yield, maturity, and credit quality. These instruments are classified as Level 2. Mutual funds, partnerships, and common and collective trusts are valued utilizing a net asset value (“NAV”) concept or its equivalent. Mutual funds, which includes exchange traded funds (“ETFs”), are classified as Level 1, and valued using a NAV that is observable and based on the active market in which the fund trades. Common and collective trusts are maintained by banks or investment companies and hold certain investments in accordance with a stated set of objectives (such as tracking the performance of the S&P 500 Index). The trust’s shares are offered to a limited group of investors and are not traded in an active market. Investments in common and collective trusts are valued using NAV as a practical expedient and, accordingly, are not classified in the fair value hierarchy. The NAV for trusts investing in exchange traded equities, and fixed income securities is derived from the market prices of the underlying securities held by the trusts. The NAV for trusts investing in real estate is derived from the appraised values of the trust’s underlying real estate assets. Investments in partnerships are also valued using the concept of NAV as a practical expedient and, accordingly, are not classified in the fair value hierarchy. The NAV for these investments is derived from the value of the partnerships’ underlying assets. The plan’s partnerships holdings relate to investments in high-yield fixed income instruments. Certain partnerships also include funding commitments that may require the plan to contribute up to $50 million to these partnerships; as of December 31, 2023, approximately $38 million of these commitments have been funded. The plans’ trustee provides valuation of our plan assets by using pricing services that utilize methodologies described to determine fair market value. We have internal control procedures to ensure this information is consistent with fair value accounting guidance. These procedures include assessing valuations using an independent pricing source, verifying that pricing can be supported by actual recent market transactions, assessing hierarchy classifications, comparing investment returns with benchmarks, and obtaining and reviewing independent audit reports on the trustee’s internal operating controls and valuation processes. The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2023, by asset category, are as follows (dollars in thousands): Level 1 Level 2 Other (a) Total Pension Plan: Fixed income securities: Corporate $ — $ 1,415,346 $ — $ 1,415,346 U.S. Treasury 622,273 — — 622,273 Other (b) — 135,184 — 135,184 Common stock equities (c) 150,657 — — 150,657 Mutual funds (d) 112,791 — — 112,791 Common and collective trusts: Equities — — 192,945 192,945 Real estate — — 140,613 140,613 Short-term investments and other (e) — — 65,740 65,740 Total $ 885,721 $ 1,550,530 $ 399,298 $ 2,835,549 Other Benefits: Fixed income securities: Corporate $ — $ 189,902 $ — $ 189,902 U.S. Treasury 207,665 — — 207,665 Other (b) — 8,372 — 8,372 Common stock equities (c) 139,952 — — 139,952 Mutual funds (d) 22,256 — — 22,256 Common and collective trusts: Equities — — 81,724 81,724 Real estate — — 20,001 20,001 Short-term investments and other (e) 21,146 — 5,476 26,622 Total $ 391,019 $ 198,274 $ 107,201 $ 696,494 (a) These investments primarily represent assets valued using NAV as a practical expedient and have not been classified in the fair value hierarchy. (b) This category consists primarily of debt securities issued by municipalities and asset backed securities. (c) This category primarily consists of U.S. common stock equities. (d) These funds invest in international common stock equities. (e) This category includes plan receivables and payables. The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2022, by asset category, are as follows (dollars in thousands): Level 1 Level 2 Other (a) Total Pension Plan: Cash and cash equivalents $ 1,252 $ — $ — $ 1,252 Fixed income securities: Corporate — 1,374,810 — 1,374,810 U.S. Treasury 635,245 — — 635,245 Other (b) — 131,999 — 131,999 Common stock equities (c) 155,231 — — 155,231 Mutual funds (d) 101,557 — — 101,557 Common and collective trusts: Equities — — 181,912 181,912 Real estate — — 174,228 174,228 Partnerships — — 13,359 13,359 Short-term investments and other (e) — — 59,892 59,892 Total $ 893,285 $ 1,506,809 $ 429,391 $ 2,829,485 Other Benefits: Cash and cash equivalents $ 204 $ — $ — $ 204 Fixed income securities: Corporate — 166,879 — 166,879 U.S. Treasury 221,936 — — 221,936 Other (b) — 7,321 — 7,321 Common stock equities (c) 127,493 — — 127,493 Mutual funds (d) 18,824 — — 18,824 Common and collective trusts: Equities — — 73,956 73,956 Real estate — — 23,541 23,541 Short-term investments and other (e) 3,274 — 8,859 12,133 Total $ 371,731 $ 174,200 $ 106,356 $ 652,287 (a) These investments primarily represent assets valued using NAV as a practical expedient and have not been classified in the fair value hierarchy. (b) This category consists primarily of debt securities issued by municipalities. (c) This category primarily consists of U.S. common stock equities. (d) These funds invest in U.S. and international common stock equities. (e) This category includes plan receivables and payables. Contributions Future year contribution amounts are dependent on plan asset performance and plan actuarial assumptions. In 2023 and 2022, we did not make any contributions to our pension plan. In 2021, we made contributions to our pension plan totaling $100 million. The minimum required contributions for the pension plan are zero for the next three years and we do not expect to make any voluntary contributions in 2024, 2025, or 2026. With regard to contributions to our other postretirement benefit plan, we did not make a contribution in 2023 or 2022 and do not expect to make any contributions in 2024, 2025 or 2026. The Company was reimbursed $23 million in 2023, $26 million in 2022, and $24 million in 2021 for prior years retiree medical claims from the other postretirement benefit plan trust assets. Estimated Future Benefit Payments Benefit payments, which reflect estimated future employee service, for the next five years and the succeeding five years thereafter, are estimated to be as follows (dollars in thousands): Year Pension Plans Other Benefits Plans 2024 $ 244,772 $ 31,024 2025 226,748 30,446 2026 229,322 30,396 2027 226,906 30,024 2028 229,397 29,741 Years 2029-2033 1,136,944 149,312 Electric plant participants contribute to the above amounts in accordance with their respective participation agreements. Employee Savings Plan Benefits Pinnacle West sponsors a defined contribution savings plan for eligible employees of Pinnacle West and its subsidiaries. In 2023, costs related to APS’s employees represented 99% of the total cost of this plan. In a defined contribution savings plan, the benefits a participant receives result from regular contributions participants make to their own individual account, the Company’s matching contributions and earnings or losses on their investments. Under this plan, the Company matches a percentage of the participants’ contributions in cash which is then invested in the same investment mix as participants elect to invest their own future contributions. Pinnacle West recorded expenses for this plan of approximately $12 million for 2023, $12 million for 2022, and $12 million for 2021.

Leases

Leases	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Leases	Leases We lease certain land, buildings, vehicles, equipment, and other property through operating rental agreements with varying terms, provisions, and expiration dates. APS also has certain purchased power and energy storage agreements that qualify as lease arrangements. Our leases have remaining terms that expire in 2024 through 2073. Substantially all of our leasing activities relate to APS. In 1986, APS entered into agreements with three separate lessor trust entities in order to sell and lease back interests in Palo Verde Unit 2 and related common facilities. These lessor trust entities have been deemed VIEs for which APS is the primary beneficiary. As the primary beneficiary, APS consolidated these lessor trust entities. The impacts of these sale leaseback transactions are excluded from our lease disclosures as lease accounting is eliminated upon consolidation. See Note 17 for a discussion of VIEs. APS has purchased power lease agreements that allow APS the right to the generation capacity from certain natural-gas fueled generators during certain months of each year throughout the term of the arrangements. As APS only has rights to use the assets during certain periods of each year, the leases have non-consecutive periods of use. APS does not operate or maintain the leased assets. APS controls the dispatch of the leased assets during the months of use and is required to pay a fixed monthly capacity payment during these periods of use. For these types of leased assets, APS has elected to combine both the lease and non-lease payment components and accounts for the entire fixed payment as a lease obligation. In addition to the fixed monthly capacity payments, APS must also pay variable charges based on the actual production volume of the assets. The variable consideration is not included in the measurement of our lease obligation. In January 2023, APS modified two existing purchase power operating lease agreements. Among other changes, the modifications extend the expiration dates of these contracts from October 2027 to October 2032 for one of the leases, and from September 2026 to October 2034 for the other lease. These lease agreements previously commenced in 2020 and 2021. APS has executed various energy storage purchased power lease agreements that allow APS the right to charge and discharge energy storage facilities. The first of these energy storage leases commenced in September 2023, and is classified as an operating lease. This agreement provides APS the use of the energy storage facility through May 2043. APS pays a fixed monthly capacity price for rights to use the leased asset. APS does not operate or maintain the energy storage facility, and has no purchase options or residual value guarantees relating to the lease asset. For this class of energy storage lease assets, APS has elected to separate the lease and non-lease components. The following table provides information related to our lease costs (dollars in thousands): Year Ended December 31, 2023 2022 2021 Operating Lease Cost - Purchased Power & Energy Storage Lease Contracts $ 126,655 $ 104,001 $ 105,762 Operating Lease Cost - Land, Property, and Other Equipment 19,235 18,061 18,498 Total Operating Lease Cost 145,890 122,062 124,260 Variable Lease Cost (a) 135,007 122,040 118,969 Short-term Lease Cost 21,530 9,928 3,872 Total Lease Cost $ 302,427 $ 254,030 $ 247,101 (a) Primarily relates to purchased power lease contracts. Lease costs are primarily included as a component of operating expenses on our Consolidated Statements of Income. Lease costs relating to purchased power and energy storage lease contracts are recorded in fuel and purchased power on the Consolidated Statements of Income and are subject to recovery under the PSA or RES. See Note 3. The tables above reflect the lease cost amounts before the effect of regulatory deferral under the PSA and RES. Variable lease costs are recognized in the period the costs are incurred, and primarily relate to renewable purchased power lease contracts. Payments under most renewable purchased power lease contracts are dependent upon environmental factors, and due to the inherent uncertainty associated with the reliability of the fuel source, the payments are considered variable and are excluded from the measurement of lease liabilities and right-of-use lease assets. Certain of our lease agreements have lease terms with non-consecutive periods of use. For these agreements we recognize lease costs during the periods of use. Leases with initial terms of 12 months or less are considered short-term leases and are not recorded on the balance sheet. The following table provides information related to the maturity of our operating lease liabilities (dollars in thousands): December 31, 2023 Year Purchased Power & Energy Storage Lease Contracts Land, Property & Equipment Leases Total 2024 $ 108,201 $ 14,750 $ 122,951 2025 124,968 12,148 137,116 2026 138,692 9,826 148,518 2027 164,613 7,731 172,344 2028 168,410 5,401 173,811 Thereafter 835,813 64,090 899,903 Total lease commitments 1,540,697 113,946 1,654,643 Less imputed interest 334,693 41,878 376,571 Total lease liabilities $ 1,206,004 $ 72,068 $ 1,278,072 We recognize lease assets and liabilities upon lease commencement. At December 31, 2023, we have various lease arrangements that have been executed, but have not yet commenced. We expect the total fixed consideration paid for these arrangements, which includes both lease and non-lease payments, will approximate $7.1 billion over the terms of the agreements. These arrangements primarily relate to energy storage assets. The lease commencement dates for these arrangements have experienced delays. APS continues to work with the lessors to determine revised commencement dates. We expect lease commencement dates ranging from April 2024 through June 2025, with lease terms expiring through May 2045. As a result of these delays and other events, APS has received cash proceeds from the lessors prior to lease commencement. Proceeds received from lessors relating to energy storage PPA leases are accounted for as lease incentives on our Consolidated Balance Sheets, and upon lease commencement are amortized over the associated lease term. For regulatory purposes, the proceeds received by APS relating to these PPA leases are treated as a reduction to fuel and purchased power costs through the PSA in the period proceeds are received. See Note 3. The following tables provide other additional information related to operating lease liabilities (dollars in thousands): Year Ended December 31, 2023 2022 2021 Cash paid for amounts included in the measurement of lease liabilities — operating cash flows: $ 123,472 $ 118,463 $ 116,661 Right-of-use operating lease assets obtained in exchange for operating lease liabilities 602,301 (a) 16,990 500,582 December 31, 2023 December 31, 2022 Weighted average remaining lease term 10 years 7 years Weighted average discount rate (b) 4.53 % 2.21 % (a) Primarily relates to the two purchased power operating lease agreements that were modified in January 2023. (b)

Jointly-Owned Facilities

Jointly-Owned Facilities	12 Months Ended
	Dec. 31, 2023
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Jointly-Owned Facilities	Jointly-Owned Facilities APS shares ownership of some of its generating and transmission facilities with other companies. We are responsible for our share of operating costs which are included in the corresponding operating expenses on our Consolidated Statements of Income. We are also responsible for providing our own financing. Our share of operating expenses and utility plant costs related to these facilities is accounted for using proportional consolidation. The following table shows APS’s interests in those jointly-owned facilities recorded on the Consolidated Balance Sheets at December 31, 2023 (dollars in thousands): Percent Plant in Accumulated Construction Generating facilities: Palo Verde Units 1 and 3 29.1 % $ 1,990,237 $ 1,087,614 $ 21,442 Palo Verde Unit 2 (a) 16.8 % 681,483 387,485 12,700 Palo Verde Common 28.0 % (b) 857,807 356,962 65,911 Palo Verde Sale Leaseback (a) 351,050 264,624 — Four Corners Generating Station 63.0 % 1,748,436 659,780 29,586 Cholla Common Facilities (c) 50.5 % 250,994 167,357 7,487 Transmission facilities: ANPP 500kV System 33.4 % (b) 136,145 58,252 4,801 Navajo Southern System 25.2 % (b) 87,185 36,743 550 Palo Verde — Yuma 500kV System 25.3 % (b) 24,057 7,912 432 Four Corners Switchyards 57.5 % (b) 84,279 21,918 161 Phoenix — Mead System 17.1 % (b) 39,772 20,679 257 Palo Verde — Rudd 500kV System 50.0 % 95,736 32,665 731 Morgan — Pinnacle Peak System 63.2 % (b) 117,080 26,990 229 Round Valley System 50.0 % 548 205 — Palo Verde — Morgan System 87.5 % (b) 268,629 40,962 8,053 Hassayampa — North Gila System 80.0 % 151,684 24,618 — Cholla 500kV Switchyard 85.7 % 8,445 2,760 — Saguaro 500kV Switchyard 60.0 % 21,627 14,060 17 Kyrene — Knox System 50.0 % 578 340 — Agua Fria Switchyard 10.0 % — — 77 (a) See Note 17. (b) Weighted-average of interests. (c)

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Palo Verde Generating Station Spent Nuclear Fuel and Waste Disposal On December 19, 2012, APS, acting on behalf of itself and the participant owners of Palo Verde, filed a second breach of contract lawsuit against the DOE in the United States Court of Federal Claims (“Court of Federal Claims”). The lawsuit sought to recover damages incurred due to DOE’s breach of the Contract for Disposal of Spent Nuclear Fuel and/or High Level Radioactive Waste (“Standard Contract”) for failing to accept Palo Verde’s spent nuclear fuel and high level waste from January 1, 2007, through June 30, 2011, pursuant to the terms of the Standard Contract and the Nuclear Waste Policy Act. On August 18, 2014, APS and DOE entered into a settlement agreement, which required DOE to pay the Palo Verde owners for certain specified costs incurred by Palo Verde during the period January 1, 2007, through June 30, 2011. In addition, the settlement agreement provided APS with a method for submitting claims and getting recovery for costs incurred through December 31, 2016, which was extended to December 31, 2025. APS has submitted nine claims pursuant to the terms of the August 18, 2014 settlement agreement, for nine separate time periods during July 1, 2011 through October 31, 2022. The DOE has approved and paid $138.2 million for these claims (APS’s share is $40.2 million). The amounts recovered were primarily recorded as adjustments to a regulatory liability and had no impact on reported net income. In accordance with the 2017 Rate Case Decision, this regulatory liability is being refunded to customers. See Note 3. On October 31, 2023, APS filed its tenth claim pursuant to the terms of the August 18, 2014, settlement agreement in the amount of $18.46 million (APS’s share is $5.4 million). In February 2024, the DOE approved $18.39 million of this claim. Nuclear Insurance Public liability for incidents at nuclear power plants is governed by the Price-Anderson Nuclear Industries Indemnity Act (“Price-Anderson Act”), which limits the liability of nuclear reactor owners to the amount of insurance available from both commercial sources and an industry-wide retrospective payment plan. This insurance limit is subject to an adjustment every five years based upon the aggregate percentage change in the Consumer Price Index. The most recent adjustment took effect on January 1, 2024. As of that date, in accordance with the Price-Anderson Act, the Palo Verde participants are insured against public liability for a nuclear incident up to approximately $16.3 billion per occurrence. Palo Verde maintains the maximum available nuclear liability insurance in the amount of $500 million, which is provided by American Nuclear Insurers. The remaining balance of approximately $15.8 billion of liability coverage is provided through a mandatory, industry-wide retrospective premium program. If losses at any nuclear power plant covered by the program exceed the accumulated funds, APS could be responsible for retrospective premiums. The maximum retrospective premium per reactor under the program for each nuclear liability incident is approximately $165.9 million, subject to a maximum annual premium of approximately $24.7 million per incident. Based on APS’s ownership interest in the three Palo Verde units, APS’s maximum retrospective premium per incident for all three units is approximately $144.9 million, with a maximum annual retrospective premium of approximately $21.6 million. The Palo Verde participants maintain insurance for property damage to, and decontamination of, property at Palo Verde in the aggregate amount of $2.8 billion. APS has also secured accidental outage insurance for a sudden and unforeseen accidental outage of any of the three units. The property damage, decontamination, and accidental outage insurance are provided by Nuclear Electric Insurance Limited (“NEIL”). APS is subject to retrospective premium adjustments under all NEIL policies if NEIL’s losses in any policy year exceed accumul ated funds. Th e maximum amount APS could incur under the current NEIL policies totals approximately $22.4 million for each retrospective premium assessment declared by NEIL’s Board of Directors due to losses. Additionally, at the sole discretion of the NEIL Board of Directors, APS would be liable to provide approximately $62.6 million in deposit premium within 20 days of request as assurance to satisfy any site obligation of retrospective premium assessment. The insurance coverage discussed in this, and the previous paragraph, is subject to certain policy conditions, sublimits, and exclusions. Fuel and Purchased Power Commitments and Purchase Obligations APS is party to various fuel and purchased power contracts and purchase obligations with terms expiring between 2024 and 2045 that include required purchase provisions. APS estimates the contract requirements to be approximately $1,034 million in 2024; $1,190 million in 2025; $1,310 million in 2026; $1,284 million in 2027; $1,292 million in 2028; and $14.7 billion thereafter. However, these amounts may vary significantly pursuant to certain provisions in such contracts that permit us to decrease required purchases under certain circumstances. These amounts include estimated commitments relating to purchased power lease contracts. See Note 8. Of the various fuel and purchased power contracts mentioned above, some of those contracts for coal supply include take-or-pay provisions. The current coal contracts with take-or-pay provisions have terms expiring through 2031. The following table summarizes our estimated coal take-or-pay commitments (dollars in thousands): Year Ended December 31, 2024 2025 2026 2027 2028 Thereafter Coal take-or-pay commitments (a) $ 208,694 $ 229,111 $ 221,122 $ 200,256 $ 205,237 $ 647,377 (a) Total take-or-pay commitments are approximately $1.7 billion. The total net present value of these commitments is approximately $1.4 billion. APS may spend more to meet its actual fuel requirements than the minimum purchase obligations in our coal take-or-pay contracts. The following table summarizes actual amounts purchased under the coal contracts which include take-or-pay provisions for each of the last three years (dollars in thousands): Year Ended December 31, 2023 2022 2021 Total purchases $ 255,219 $ 305,502 $ 219,958 Renewable Energy Credits APS has entered into contracts to purchase renewable energy credits to comply with the RES. APS estimates the contract requirements to be approximately $29 million in 2024; $27 million in 2025; $24 million in 2026; $20 million in 2027; $17 million in 2028; and $52 million thereafter. These amounts do not include purchases of renewable energy credits that are bundled with energy. Coal Mine Reclamation Obligations APS must reimburse certain coal providers for final and contemporaneous coal mine reclamation. We account for contemporaneous reclamation costs as part of the cost of the delivered coal. We utilize site-specific studies of costs expected to be incurred in the future to estimate our final reclamation obligation. These studies utilize various assumptions to estimate the future costs. Based on the most recent reclamation studies, APS recorded an obligation for the coal mine final reclamation of approximately $184 million at December 31, 2023, and $179 million at December 31, 2022. Under our current coal supply agreements, APS expects to make payments for the final mine reclamation as follows: $19 million in 2024; $20 million in 2025; $21 million in 2026; $22 million in 2027; $23 million in 2028; and $2 million thereafter. These funds are held in an escrow account and will be distributed to certain coal providers under the terms of the applicable coal supply agreements. Any amendments to current coal supply agreements may change the timing of the contribution or cost of final reclamation. The annual payments to the escrow account and final distribution to certain coal providers may be subject to adjustments based on escrow earnings. Superfund and Other Related Matters The Comprehensive Environmental Response Compensation and Liability Act (“Superfund” or “CERCLA”) establishes liability for the cleanup of hazardous substances found contaminating the soil, water or air. Those who released, generated, transported to or disposed of hazardous substances at a contaminated site are among the parties who are potentially responsible (each a “PRP”). PRPs may be strictly, jointly, and severally liable for clean-up. On September 3, 2003, EPA advised APS that EPA considers APS to be a PRP in the Motorola 52nd Street Superfund Site, Operable Unit 3 (“OU3”) in Phoenix, Arizona. APS has facilities that are within this Superfund site. APS and Pinnacle West have agreed with EPA to perform certain investigative activities of the APS facilities within OU3. In addition, on September 23, 2009, APS agreed with EPA and one other PRP to voluntarily assist with the funding and management of the site-wide groundwater remedial investigation and feasibility study (“RI/FS”). The RI/FS for OU3 was finalized and submitted to EPA at the end of 2022. APS cannot predict the EPA’s timing with respect to this matter. APS’s estimated costs related to this investigation and study is approximately $3 million. APS anticipates incurring additional expenditures in the future, but because the ultimate remediation requirements are not yet finalized by EPA, at the present time expenditures related to this matter cannot be reasonably estimated. In connection with APS’s status as a PRP for OU3, since 2013, APS and at least two dozen other parties have been defendants in various CERCLA lawsuits stemming from allegations that contamination from OU3 and elsewhere has impacted groundwater wells operated by the Roosevelt Irrigation District (“RID”). At this time, only one active lawsuit remains pending, which is on appeal to the U.S. Court of Appeals for the Ninth Circuit based on a U.S. District Court order dismissing cost recovery claims of approximately $20.7 million by a service provider for RID. APS is unable to predict the outcome of any further litigation related to this claim or APS’s share of liability related to that claim; however, APS does not expect the outcome to have a material impact on our financial position, results of operations or cash flows. In addition, as part of a state governmental investigation into groundwater contamination in this area, on January 25, 2015, the ADEQ sent a letter to APS seeking information concerning the degree to which, if any, APS’s current and former ownership of these facilities may have contributed to groundwater contamination in this area. APS responded to ADEQ on May 4, 2015. Since that time, ADEQ has taken no action based on the information provided by APS. On February 28, 2022, EPA provided APS with a request for information under CERCLA related to APS’s Ocotillo power plant site located in Tempe, Arizona. In particular, EPA seeks information from APS regarding APS’s use, storage, and disposal of substances containing per-and polyfluoroalkyl (“PFAS”) compounds at the Ocotillo power plant site in order to aid EPA’s investigation into actual or threatened releases of PFAS into groundwater within the South Indian Bend Wash (“SIBW”) Superfund site. The SIBW Superfund site includes the APS Ocotillo power plant site. APS filed its response to this information request on April 29, 2022. On January 17, 2023, EPA contacted APS to inform the Company that it would be commencing on-site investigations within the SIBW site, including the Ocotillo power plant, and performing a remedial investigation and feasibility study related to potential PFAS impacts to groundwater over the next two to three years. APS estimates that its costs to oversee and participate in the remedial investigation work will be approximately $1.7 million. At the present time, we are unable to predict the outcome of this matter and any further expenditures related to necessary remediation, if any, or further investigations cannot be reasonably estimated. Four Corners SCR Cost Recovery As part of APS’s 2019 Rate Case, APS included recovery of the deferral and rate base effects of the Four Corners SCR project. On November 2, 2021, the 2019 Rate Case decision was approved by the ACC allowing approximately $194 million of SCR related plant investments and cost deferrals in rate base and to recover, depreciate and amortize in rates based on an end-of-life assumption of July 2031. The decision also included a partial and combined disallowance of $215.5 million on the SCR investments and deferrals. APS believes the SCR plant investments and related SCR cost deferrals were prudently incurred, and on December 17, 2021, APS filed its Notice of Direct Appeal at the Arizona Court of Appeals requesting review of the $215.5 million disallowance. The Arizona Court of Appeals heard oral arguments on November 30, 2022. On March 6, 2023, the Court of Appeals issued its order in the matter, vacating the ACC’s disallowance of the SCR investment and remanding the matter back to the ACC for further review in accordance with ACC rules and the order of the Court of Appeals. On June 21, 2023, the ACC approved a joint settlement filed by APS and the ACC’s Legal Division that resolved all issues relating to the 2019 Rate Case decision, including recovery of the cost of the Four Corners SCRs. See Note 3 for additional information regarding the Four Corners SCR cost recovery and the 2019 Rate Case. Environmental Matters APS is subject to numerous environmental laws and regulations affecting many aspects of its present and future operations, including air emissions of both conventional pollutants and greenhouse gases, water quality, wastewater discharges, solid waste, hazardous waste, and coal combustion residuals (“CCRs”). These laws and regulations can change from time to time, imposing new obligations on APS resulting in increased capital, operating, and other costs. Associated capital expenditures or operating costs could be material. APS intends to seek recovery of any such environmental compliance costs through our rates but cannot predict whether it will obtain such recovery. The following proposed and final rules could involve material compliance costs to APS. Coal Combustion Waste . On December 19, 2014, EPA issued its final regulations governing the handling and disposal of CCR, such as fly ash and bottom ash. The rule regulates CCR as a non-hazardous waste under Subtitle D of the Resource Conservation and Recovery Act (“RCRA”) and establishes national minimum criteria for existing and new CCR landfills and surface impoundments and all lateral expansions. These criteria include standards governing location restrictions, design and operating criteria, groundwater monitoring and corrective action, closure requirements and post closure care, and recordkeeping, notification, and internet posting requirements. The rule generally requires any existing unlined CCR surface impoundment to stop receiving CCR and either retrofit or close, and further requires the closure of any CCR landfill or surface impoundment that cannot meet the applicable performance criteria for location restrictions or structural integrity. Such closure requirements are deemed “forced closure” or “closure for cause” of unlined surface impoundments and are the subject of the regulatory and judicial activities described below. Since these regulations were finalized, EPA has taken steps to substantially modify the federal rules governing CCR disposal. While certain changes have been prompted by utility industry petitions, others have resulted from judicial review, court-approved settlements with environmental groups, and statutory changes to RCRA. The following lists the pending regulatory changes that, if finalized, could have a material impact as to how APS manages CCR at its coal-fired power plants: • Following the passage of the Water Infrastructure Improvements for the Nation Act in 2016, EPA possesses authority to either authorize states to develop their own permit programs for CCR management or issue federal permits governing CCR disposal both in states without their own permit programs and on tribal lands. Although ADEQ has taken steps to develop a CCR permitting program, and new state legislation has been adopted providing ADEQ with appropriate permitting authority for CCR under the state solid waste management program, it is not clear when that program will be put into effect. On December 19, 2019, EPA proposed its own set of regulations governing the issuance of CCR management permits, which would impact facilities like Four Corners located on the Navajo Nation. The proposal remains pending. • On March 1, 2018, as a result of a settlement with certain environmental groups, EPA proposed adding boron to the list of constituents that trigger corrective action requirements to remediate groundwater impacted by CCR disposal activities. Apart from a subsequent proposal issued on August 14, 2019, to add a specific, health-based groundwater protection standard for boron, EPA has yet to take action on this proposal. • With respect to APS’s Cholla facility, APS’s application for alternative closure was submitted to EPA on November 30, 2020. While EPA has deemed APS’s application administratively “complete,” the Agency’s approval remains pending. If granted, this application would allow the continued disposal of CCR within Cholla’s existing unlined CCR surface impoundments until the required date for ceasing coal-fired boiler operations in April 2025. This application will be subject to public comment and, potentially, judicial review. We expect to have a proposed decision from EPA regarding Cholla sometime in 2024. • On May 18, 2023, EPA published a proposal that expands the scope of federal CCR regulations to address the impacts from historical CCR disposal activities that would have ceased prior to 2015. EPA proposes to define a new class of CCR management units (“CCRMUs”) that broadly encompass any location at an operating coal-fired power plant where CCR would have been placed on land. As proposed, this would include not only historically closed landfills and surface impoundments but also prior applications of CCR beneficial use. EPA expects to finalize this proposal by spring of 2024. We cannot at this time predict the outcome of these regulatory proceedings or when EPA will take final action on those matters that are still pending. Depending on the eventual outcome, the costs associated with APS’s management of CCR could materially increase, which could affect our financial condition, results of operations, or cash flows. APS currently disposes of CCR in ash ponds and dry storage areas at Cholla and Four Corners. The Navajo Plant disposed of CCR only in a dry landfill storage area. Additionally, the CCR rule requires ongoing, phased groundwater monitoring. As of October 2018, APS has completed the statistical analyses for its CCR disposal units that triggered assessment monitoring. APS determined that several of its CCR disposal units at Cholla and Four Corners will need to undergo corrective action. In addition, under the current regulations, all such disposal units must have ceased operating and initiated closure by April 11, 2021, at the latest (except for those disposal units subject to alternative closure). APS completed the assessments of corrective measures on June 14, 2019; however, additional investigations and engineering analyses that will support the remedy selection are still underway. In addition, APS will also solicit input from the public and host public hearings as part of this process. APS’s estimates for its share of corrective action and monitoring costs at Four Corners and Cholla are captured within the Asset Retirement Obligations. S ee Note 11 . As APS continues to implement the CCR rule’s corrective action assessment process, the current cost estimates may change. Given uncertainties that may exist until we have fully completed the corrective action assessment and final remedy selection process, APS cannot predict any ultimate impacts to APS; however, at this time APS does not believe that any potential changes to the cost estimate for Four Corners or Cholla would have a material impact on its financial condition, results of operations, or cash flows. EPA Power Plant Carbon Regulations. EPA’s regulation of carbon dioxide emissions from electric utility power plants has proceeded in fits and starts over most of the last decade. Starting on August 3, 2015, EPA finalized the Clean Power Plan, which was the Agency’s first effort at such regulation through system-wide generation dispatch shifting. Those regulations were subsequently repealed by the EPA on June 19, 2019, and replaced by the Affordable Clean Energy (“ACE”) regulations, which were a far narrower set of rules. While the U.S. Court of Appeals for the D.C. Circuit subsequently vacated the ACE regulations on January 19, 2021, and ordered a remand for EPA to develop replacement regulations consistent with the original 2015 Clean Power Plan, the U.S. Supreme Court subsequently reversed that decision on June 30, 2022, holding that the Clean Power Plan exceeded EPA’s authority under the Clean Air Act. In the latest set of proposed rules, released on May 23, 2023, EPA contemplates emission standards and guidelines for various subcategories of new and existing power plants. Unlike EPA’s Clean Power Plan regulations from 2015, which took a broad, system-wide approach to regulating carbon emissions from electric utility fossil-fuel burning power plants, the most recent proposal is limited to measures that can be installed at individual power plants to limit planet-warming emissions. As such, for new natural gas-fired combustion turbine power plants, EPA is proposing that carbon emission performance standards apply based on the annual capacity factors. For the highest utilization combustion turbines, EPA is therefore proposing that such facilities be retrofitted for carbon capture and sequestration or utilization controls (“CCS”) or varying levels of hydrogen gas (“H2”) co-firing. As for existing natural gas-fired combustion turbines, EPA is imposing similar control requirements at large, high utilization generating units, but is otherwise not proceeding at this time with further regulation. As such, under EPA’s proposal, this means that both new and existing peaking gas-fired combustion turbines (i.e., those with a 20% or less annual capacity factor) are effectively unregulated under the proposed regulations. For coal-fired power plants, instead of imposing regulations based on capacity and utilization, EPA has developed subcategories based on planned retirement dates. This means that facilities retiring between 2030 and before 2040 must meet increasingly stringent emission limits up to natural-gas co-firing starting in 2030. However, for those facilities with no planned retirement date prior to 2040, EPA is requiring those plants to be retrofitted with CCS controls by 2030. EPA expects to take final action on this proposal by spring or summer of 2024. At this time, APS cannot predict the outcome of this rulemaking or when EPA will take final action. In addition, APS is continuing to evaluate this proposal and its potential impact on APS’s operations. Depending on the eventual outcome, the costs associated with APS’s operation of its current and future thermal power plants could materially increase, which could affect our financial condition, results of operations, or cash flows. Other environmental rules that could involve material compliance costs include those related to effluent limitations, the ozone national ambient air quality standard and other rules or matters involving the Clean Air Act, Clean Water Act, Endangered Species Act, RCRA, Superfund, the Navajo Nation, and water supplies for our power plants. The financial impact of complying with current and future environmental rules could jeopardize the economic viability of APS’s fossil-fuel powered plants or the willingness or ability of power plant participants to fund any required equipment upgrades or continue their participation in these plants. The economics of continuing to own certain resources, particularly our coal plants, may deteriorate, warranting early retirement of those plants, which may result in asset impairments. APS would seek recovery in rates for the book value of any remaining investments in the plants, as well as other costs related to early retirement, but cannot predict whether it would obtain such recovery. Four Corners National Pollutant Discharge Elimination System (“NPDES”) Permit The latest NPDES permit for Four Corners was issued on September 30, 2019. Based upon a November 1, 2019, filing by several environmental groups, the Environmental Appeals Board (“EAB”) took up review of the Four Corners NPDES Permit. The EAB denied the environmental group petition on September 30, 2020. While on January 22, 2021, the environmental groups filed a petition for review of the EAB’s decision with the U.S. Court of Appeals for the Ninth Circuit, the parties to the litigation (including APS) finalized a settlement on May 2, 2022. This settlement requires investigation of thermal wastewater discharges from Four Corners, administratively closes the litigation filed in January of 2021, and APS does not expect the outcome to have a material impact on our financial condition, results of operations, or cash flows. Four Corners — 4CA Matter On July 6, 2016, 4CA purchased El Paso Electric Company’s 7% interest in Four Corners. NTEC purchased this 7% interest on July 3, 2018, from 4CA. NTEC purchased the 7% interest at 4CA’s book value, approximately $70 million, and paid 4CA the purchase price over a period of four years pursuant to a secured interest-bearing promissory note, which was paid in full as of June 30, 2022. In connection with the sale, Pinnacle West guaranteed certain obligations that NTEC will have to the other owners of Four Corners, such as NTEC’s 7% share of capital expenditures and operating and maintenance expenses. Pinnacle West’s guarantee is secured by a portion of APS’s payments to be owed to NTEC under the 2016 Coal Supply Agreement. PNW Power Wind Projects In October 2023, the Tenaska wind farm investments were reorganized such that they are no longer held by BCE, rather they are now held under the new Pinnacle West subsidiary, PNW Power. See Notes 1 and 20 for more information. Tenaska Clear Creek Wind, LLC, the developer, owner, and operator of the Clear Creek wind farm, has disputed the proposed cost allocation of system upgrades related to connecting the Clear Creek wind farm to the transmission system. Tenaska Clear Creek Wind, LLC, filed complaints with FERC on this matter on May 21, 2021, and May 25, 2022, both of which FERC has denied. In April 2023, Tenaska Clear Creek Wind, LLC filed Petitions for Review of the relevant FERC orders with the U.S. Court of Appeals for the D.C. Circuit, which are still pending. Due to disputed system upgrades and curtailment issues, the Clear Creek wind farm has experienced a significant reduction in power generation that has had a material adverse impact on the project’s ability to generate cash flow for investors. During the fourth quarter of 2022, due to these ongoing disputes, cost allocation uncertainties, and no probable favorable resolution, the equity method investment was fully impaired. Prior to the impairment, the investment had a carrying value of $17.1 million, which was written-down to reflect the investment’s estimated fair value of zero as of December 31, 2022. Pinnacle West’s Consolidated Statement of Income for the year ended December 31, 2022, includes an after-tax loss of $12.8 million relating to this impairment. BCE Kūpono Solar BCE and Ameresco jointly owned a special purpose entity that is sponsoring the Kūpono Solar project. This project is a 42 MW solar and battery storage facility in Oʻahu, Hawaii that will supply clean renewable energy and capacity under a 20-year power purchase agreement with Hawaiian Electric Company, Inc. The Kūpono Solar project is expected to be completed in 2024. On April 18, 2023, the Kūpono Solar special purpose entity entered into a $140 million non-recourse construction financing agreement. The construction financing will convert into a sale leaseback agreement upon commercial operation of the project. As of December 31, 2023, the construction financing agreement required $40 million of sponsor equity, which has been funded by the project’s equity participants and which is subject to adjustment under the construction financing agreement. In connection with the financing, Pinnacle West has issued performance guarantees relating to the project. Investments in the Kūpono Solar project are included in the BCE Sale which closed on January 12, 2024. Subsequent to the BCE Sale, Pinnacle West continues to maintain the performance guarantees relating to the Kūpono Solar project financing, see additional information below regarding these guarantees. See Note 20 for information relating to the BCE Sale. Financial Assurances In the normal course of business, we obtain standby letters of credit and surety bonds from financial institutions and other third parties. These instruments guarantee our own future performance and provide third parties with financial and performance assurance in the event we do not perform. These instruments support commodity contract collateral obligations and other transactions. As of December 31, 2023, standby letters of credit totaled approximately $27 million and will expire in 2024. As of December 31, 2023, surety bonds expiring through 2025 totaled approximately $20 million. The underlying liabilities insured by these instruments are reflected on our balance sheets, where applicable. Therefore, no additional liability is reflected for the letters of credit and surety bonds themselves. We enter into agreements that include indemnification provisions relating to liabilities arising from or related to certain of our agreements. Most significantly, APS has agreed to indemnify the equity participants and other parties in the Palo Verde sale leaseback transactions with respect to certain tax matters. Generally, a maximum obligation is not explicitly stated in the indemnification provisions and, therefore, the overall maximum amount of the obligation under such indemnification provisions cannot be reasonably estimated. Based on historical experience and evaluation of the specific indemnities, we do not believe that any material loss related to such indemnification provisions is likely. Pinnacle West has issued parental guarantees and has provided indemnification under certain surety bonds for APS which were not material at December 31, 2023. In connection with the sale of 4CA’s 7% interest to NTEC, Pinnacle West is guaranteeing certain obligations that NTEC will have to the other owners of Four Corners. See “Four Corners — 4CA Matter” above for information related to this guarantee. Pinnacle West has not needed to perform under this guarantee. A maximum obligation is not explicitly stated in the guarantee and, therefore, the overall maximum amount of the obligation under such guarantee cannot be reasonably estimated; however, we consider the fair value of this guarantee, including expected credit losses, to be immaterial. In connection with PNW Power’s investments in minority ownership positions in the Clear Creek wind farm in Missouri and Nobles 2 wind farm in Minnesota, Pinnacle West has guaranteed the obligations of PNW Power to make production tax credit funding payments to borrowers of the projects (the “PTC Guarantees”). The amounts guaranteed by Pinnacle West are reduced as payments are made under the respective guarantee agreements. As of December 31, 2023, there is approximately $31 million of remaining guarantees relating to these PTC Guarantees that are expected to terminate by 2030. Pinnacle West has issued various performance guarantees in connection with BCE’s Kūpono Solar project investment financing, and is exposed to losses relating to these guarantees upon the occurrence of certain events that we do not consider to be reasonably likely to occur. Subsequent to the BCE Sale, Pinnacle West continues to maintain these performance guarantees. See Note 20. As of December 31, 2023, these performance guarantees had no significant impact on our Consolidated Balance Sheets or Consolidated Statements of Income. The details of the guarantees are as follows: • Upon the BCE

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2023
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations In 2023, the Company revised its cost estimates for existing Asset Retirement Obligations (“ARO”) for the following: • Cholla coal-fired power plant related to the closure of ponds and facilities, which resulted in an increase to the ARO of approximately $71 million, primarily due to changes in the planned pond closure methodology and increased corrective action cost estimates associated with the CCR Rule. See Note 10. • Four Corners coal-fired power plant, which resulted in a decrease of approximately $7 million. • Navajo coal-fired plant, which resulted in an increase of approximately $8 million. • Palo Verde received a new decommissioning study, which resulted in an increase to the ARO in the amount of $63 million, an increase in the plant in service of $59 million and a decrease in the regulatory liability of $4 million. In 2022, APS did not revise any cost estimates related to existing AROs, and no new AROs were necessary. See additional details in Notes 3 and 10. The following table shows the change in our AROs (dollars in thousands): 2023 2022 Asset retirement obligations at the beginning of year $ 797,762 $ 767,382 Changes attributable to: Accretion expense 44,269 41,240 Settlements (14,039) (10,860) Estimated cash flow revisions 135,323 — Newly incurred obligation 2,686 — Asset retirement obligations at the end of year $ 966,001 $ 797,762 In accordance with regulatory accounting, APS accrues removal costs for its regulated utility assets, even if there is no legal obligation for removal. See detail of regulatory liabilities in Note 3.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements We classify our assets and liabilities that are carried at fair value within the fair value hierarchy. This hierarchy ranks the quality and reliability of the inputs used to determine fair values, which are then classified and disclosed in one of three categories. The three levels of the fair value hierarchy are: Level 1 — Inputs are unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 — Other significant observable inputs, including quoted prices in active markets for similar assets or liabilities; quoted prices in markets that are not active, and model-derived valuations whose inputs are observable (such as yield curves). Level 3 — Valuation models with significant unobservable inputs that are supported by little or no market activity. Instruments in this category may include long-dated derivative transactions where valuations are unobservable due to the length of the transaction, options, and transactions in locations where observable market data does not exist. The valuation models we employ utilize spot prices, forward prices, historical market data and other factors to forecast future prices. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Thus, a valuation may be classified in Level 3 even though the valuation may include significant inputs that are readily observable. We maximize the use of observable inputs and minimize the use of unobservable inputs. We rely primarily on the market approach of using prices and other market information for identical and/or comparable assets and liabilities. If market data is not readily available, inputs may reflect our own assumptions about the inputs market participants would use. Our assessment of the inputs and the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities as well as their placement within the fair value hierarchy levels. We assess whether a market is active by obtaining observable broker quotes, reviewing actual market activity, and assessing the volume of transactions. We consider broker quotes observable inputs when the quote is binding on the broker, we can validate the quote with market activity, or we can determine that the inputs the broker used to arrive at the quoted price are observable. Instruments valued using NAV as a practical expedient are included in our fair value disclosures; however, in accordance with GAAP are not classified within the fair value hierarchy levels. Recurring Fair Value Measurements We apply recurring fair value measurements to cash equivalents, derivative instruments, and investments held in the nuclear decommissioning trusts and other special use funds. On an annual basis, we apply fair value measurements to plan assets held in our retirement and other benefit plans. See Note 7 for fair value discussion of plan assets held in our retirement and other benefit plans. Cash Equivalents Cash equivalents represent certain investments in money market funds that are valued using quoted prices in active markets. Risk Management Activities — Energy Derivative Instruments Exchange traded commodity contracts are valued using unadjusted quoted prices. For non-exchange traded commodity contracts, we calculate fair value based on the average of the bid and offer price, discounted to reflect net present value. We maintain certain valuation adjustments for a number of risks associated with the valuation of future commitments. These include valuation adjustments for liquidity and credit risks. The liquidity valuation adjustment represents the cost that would be incurred if all unmatched positions were closed out or hedged. The credit valuation adjustment represents estimated credit losses on our net exposure to counterparties, taking into account netting agreements, expected default experience for the credit rating of the counterparties and the overall diversification of the portfolio. We maintain credit policies that management believes minimize overall credit risk. Certain non-exchange traded commodity contracts are valued based on unobservable inputs due to the long-term nature of contracts, characteristics of the product, or the unique location of the transactions. Long-dated energy transactions may consist of observable valuations for the near-term portion and unobservable valuations for the long-term portions of the transaction. We rely primarily on broker quotes to value these instruments. When our valuations utilize broker quotes, we perform various control procedures to ensure the quote has been developed consistent with fair value accounting guidance. These controls include assessing the quote for reasonableness by comparison against other broker quotes, reviewing historical price relationships, and assessing market activity. When broker quotes are not available, the primary valuation technique used to calculate the fair value is the extrapolation of forward pricing curves using observable market data for more liquid delivery points in the same region and actual transactions at more illiquid delivery points. When the unobservable portion is significant to the overall valuation of the transaction, the entire transaction is classified as Level 3. Risk Management Activities — Interest Rate Derivatives Our interest rate derivative instruments related to a BCE interest rate swap, which was valued using financial models that utilize observable inputs for similar instruments and was classified as Level 2. The interest rate swap is no longer held as of December 31, 2023. See Note 20. Investments Held in Nuclear Decommissioning Trusts and Other Special Use Funds The nuclear decommissioning trusts and other special use funds invest in fixed income and equity securities. Other special use funds include the coal reclamation escrow account and the active union employee medical account. See Note 18 for additional discussion about our investment accounts. We value investments in fixed income and equity securities using information provided by our trustees and escrow agent. Our trustees and escrow agent use pricing services that utilize the valuation methodologies described below to determine fair market value. We have internal control procedures designed to ensure this information is consistent with fair value accounting guidance. These procedures include assessing valuations using an independent pricing source, verifying that pricing can be supported by actual recent market transactions, assessing hierarchy classifications, comparing investment returns with benchmarks, and obtaining and reviewing independent audit reports on the trustees’ and escrow agent’s internal operating controls and valuation processes. Fixed Income Securities Fixed income securities issued by the U.S. Treasury are valued using quoted active market prices and are typically classified as Level 1. Fixed income securities issued by corporations, municipalities, and other agencies, including mortgage-backed instruments, are valued using quoted inactive market prices, quoted active market prices for similar securities, or by utilizing calculations which incorporate observable inputs such as yield curves and spreads relative to such yield curves. These fixed income instruments are classified as Level 2. Whenever possible, multiple market quotes are obtained which enables a cross-check validation. A primary price source is identified based on asset type, class, or issue of securities. Fixed income securities may also include short-term investments in certificates of deposit, variable rate notes, time deposit accounts, U.S. Treasury and Agency obligations, U.S. Treasury repurchase agreements, commercial paper, and other short-term instruments. These instruments are valued using active market prices or utilizing observable inputs described above. Equity Securities The nuclear decommissioning trusts’ equity security investments are held indirectly through commingled funds. The commingled funds are valued using the funds’ NAV as a practical expedient. The funds’ NAV is primarily derived from the quoted active market prices of the underlying equity securities held by the funds. We may transact in these commingled funds on a semi-monthly basis at the NAV. The commingled funds are maintained by a bank and hold investments in accordance with the stated objective of tracking the performance of the S&P 500 Index. Because the commingled funds’ shares are offered to a limited group of investors, they are not considered to be traded in an active market. As these instruments are valued using NAV, as a practical expedient, they have not been classified within the fair value hierarchy. The nuclear decommissioning trusts and other special use funds may also hold equity securities that include exchange traded mutual funds and money market accounts for short-term liquidity purposes. These short-term, highly-liquid investments are valued using active market prices. Fair Value Tables The following table presents the fair value at December 31, 2023, of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands): Balance at December 31, 2023 Level 1 Level 2 Level 3 Other Total ASSETS Cash equivalents $ 10 $ — $ — $ — $ 10 Risk management activities — derivative instruments: Commodity contracts — 1,881 6,616 (1,689) (a) 6,808 Nuclear decommissioning trust: Equity securities 11,064 — — (767) (b) 10,297 U.S. commingled equity funds — — — 409,616 (c) 409,616 U.S. Treasury debt 319,734 — — — 319,734 Corporate debt — 188,317 — — 188,317 Mortgage-backed securities — 208,306 — — 208,306 Municipal bonds — 59,323 — — 59,323 Other fixed income — 5,653 — — 5,653 Subtotal nuclear decommissioning trust 330,798 461,599 — 408,849 1,201,246 Other special use funds: Equity securities 40,991 — — 2,196 (b) 43,187 U.S. Treasury debt 319,594 — — — 319,594 Municipal bonds — — — — — Subtotal other special use funds 360,585 — — 2,196 362,781 Total assets $ 691,393 $ 463,480 $ 6,616 $ 409,356 $ 1,570,845 LIABILITIES Risk management activities — derivative instruments: Commodity contracts $ — $ (127,016) $ (1,695) $ 4,823 (a) $ (123,888) (a) Represents counterparty netting, margin, and collateral. See Note 15. (b) Represents net pending securities sales and purchases. (c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy. The following table presents the fair value at December 31, 2022, of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands): Balance at December 31, 2022 Level 1 Level 2 Level 3 Other Total ASSETS Risk management activities — derivative instruments: Commodity contracts $ — $ 127,129 $ 26,132 $ (21,163) (a) $ 132,098 Interest rate swaps — 131 — — 131 Subtotal risk management activities - derivative instruments — 127,260 26,132 (21,163) 132,229 Nuclear decommissioning trust: Equity securities 14,658 — — 3,827 (b) 18,485 U.S. commingled equity funds — — — 472,582 (c) 472,582 U.S. Treasury debt 211,923 — — — 211,923 Corporate debt — 149,226 — — 149,226 Mortgage-backed securities — 147,938 — — 147,938 Municipal bonds — 64,881 — — 64,881 Other fixed income — 8,375 — — 8,375 Subtotal nuclear decommissioning trust 226,581 370,420 — 476,409 1,073,410 Other special use funds: Equity securities 66,974 — — 963 (b) 67,937 U.S. Treasury debt 275,267 — — — 275,267 Municipal bonds — 4,027 — — 4,027 Subtotal other special use funds 342,241 4,027 — 963 347,231 Total assets $ 568,822 $ 501,707 $ 26,132 $ 456,209 $ 1,552,870 LIABILITIES Risk management activities — derivative instruments: Commodity contracts $ — $ (25,874) $ (31,020) $ 15,357 (a) $ (41,537) Interest rate swaps — (909) — — (909) Subtotal risk management activities - derivative instruments — (26,783) (31,020) 15,357 (42,446) Total liabilities $ — $ (26,783) $ (31,020) $ 15,357 $ (42,446) (a) Represents counterparty netting, margin, and collateral. See Note 15. (b) Represents net pending securities sales and purchases. (c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy. Fair Value Measurements Classified as Level 3 The significant unobservable inputs used in the fair value measurement of our energy derivative contracts include broker quotes that cannot be validated as an observable input primarily due to the long-term nature of the quote or other characteristics of the product. Significant changes in these inputs in isolation would result in significantly higher or lower fair value measurements. Changes in our derivative contract fair values, including changes relating to unobservable inputs, typically will not impact net income due to regulatory accounting treatment. See Note 3. Because our forward commodity contracts classified as Level 3 are currently in a net purchase position, we would expect price increases of the underlying commodity to result in increases in the net fair value of the related contracts. Conversely, if the price of the underlying commodity decreases, the net fair value of the related contracts would likely decrease. Other unobservable valuation inputs include credit and liquidity reserves which do not have a material impact on our valuations; however, significant changes in these inputs could also result in higher or lower fair value measurements. The following tables provide information regarding our significant unobservable inputs used to value our risk management derivative Level 3 instruments at December 31, 2023, and December 31, 2022: December 31, 2023 Valuation Significant Weighted-Average Commodity Contracts Assets Liabilities Technique Unobservable Input Range (b) Electricity: Forward Contracts (a) $ 6,587 $ 658 Discounted cash flows Electricity forward price (per MWh) $37.79 - $259.04 $ 158.08 Natural Gas: Forward Contracts (a) 29 1,037 Discounted cash flows Natural gas forward price (per MMBtu) $0.00 - $0.08 $ 0.03 Total $ 6,616 $ 1,695 (a) Includes swaps and physical and financial contracts. (b) Unobservable inputs were weighted by the relative fair value of the instrument. December 31, 2022 Valuation Significant Weighted-Average Commodity Contracts Assets Liabilities Technique Unobservable Input Range (b) Electricity: Forward Contracts (a) $ 26,132 $ 1,759 Discounted cash flows Electricity forward price (per MWh) $ 37.79 - $ 310.69 $ 163.92 Natural Gas: Forward Contracts (a) — 29,261 Discounted cash flows Natural gas forward price (per MMBtu) $(11.81) - $0.00 $ (5.08) Total $ 26,132 $ 31,020 (a) Includes swaps and physical and financial contracts. (b) Unobservable inputs were weighted by the relative fair value of the instrument. The following table shows the changes in fair value for our risk management activities’ assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs (dollars in thousands): Year Ended December 31, Commodity Contracts 2023 2022 Net derivative balance at beginning of period $ (4,888) $ (2,738) Total net gains (losses) realized/unrealized: Deferred as a regulatory asset or liability (70,214) (374) Settlements 69,706 (1,123) Transfers into Level 3 from Level 2 (1,289) (846) Transfers from Level 3 into Level 2 11,606 193 Net derivative balance at end of period $ 4,921 $ (4,888) Net unrealized gains included in earnings related to instruments still held at end of period $ — $ — Transfers in or out of Level 3 are typically related to our long-dated energy transactions that extend beyond available quoted periods. Financial Instruments Not Carried at Fair Value

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table presents the calculation of Pinnacle West’s basic and diluted earnings per share (in thousands, except per share amounts): 2023 2022 2021 Net income attributable to common shareholders $ 501,557 $ 483,602 $ 618,720 Weighted average common shares outstanding — basic 113,442 113,196 112,910 Net effect of dilutive securities: Contingently issuable performance shares and restricted stock units 362 220 282 Weighted average common shares outstanding — diluted 113,804 113,416 113,192 Earnings per weighted-average common share outstanding Net income attributable to common shareholders — basic $ 4.42 $ 4.27 $ 5.48 Net income attributable to common shareholders — diluted $ 4.41 $ 4.26 $ 5.47

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation Pinnacle West has incentive compensation plans under which stock-based compensation is granted to officers, key-employees, and non-officer members of the Board of Directors. Awards granted under the 2021 Long-Term Incentive Plan (“2021 Plan”) may be in the form of stock grants, restricted stock units, stock units, performance shares, restricted stock, dividend equivalents, performance share units, performance cash, incentive and non-qualified stock options, and stock appreciation rights. The 2021 Plan authorizes up to 4.3 million common shares to be available for grant. As of December 31, 2023, 3.5 million common shares were available for issuance under the 2021 Plan. During 2023, 2022 and 2021, the Company granted awards in the form of restricted stock units, stock units, stock grants, and performance shares. Awards granted from 2012 to May 2021 were issued under the 2012 Long-Term Incentive Plan (“2012 Plan”), and awards granted from 2007 to 2011 were issued under the 2007 Long-Term Incentive Plan (“2007 Plan”). No new awards may be granted under the 2012 or 2007 Plans. Stock-Based Compensation Expense and Activity Compensation cost included in net income for stock-based compensation plans was $17 million in 2023, $16 million in 2022, and $18 million in 2021. The compensation cost capitalized is immaterial for all years. Income tax benefits related to stock-based compensation arrangements were $3 million in 2023, $2 million in 2022, and $3 million in 2021. As of December 31, 2023, there were approximately $31 million of unrecognized compensation costs related to nonvested stock-based compensation arrangements. We expect to recognize these costs over a weighted-average period of two years. The total fair value of shares vested was $24 million in 2023, $25 million in 2022, and $22 million in 2021. The following table is a summary of awards granted and the weighted-average grant date fair value for each of the last three years: Restricted Stock Units, Stock Grants, and Stock Units (a) Performance Shares (b) 2023 2022 2021 2023 2022 2021 Units granted 192,295 174,791 152,345 202,562 208,736 161,840 Weighted-average grant date fair value $ 74.32 $ 69.66 $ 76.72 $ 79.61 $ 77.63 $ 82.42 (a) Units granted includes awards that will be cash settled of 0 in 2023, 0 in 2022, and 51,074 in 2021. See below for additional information on restricted stock unit grants. (b) Reflects the target payout level. The following table shows the change of nonvested awards: Restricted Stock Units, Stock Grants, and Stock Units Performance Shares Shares Weighted-Average Shares (b) Weighted-Average Nonvested at December 31, 2022 317,587 $ 73.91 330,694 $ 78.91 Granted 192,295 74.32 202,562 79.61 Vested (119,077) 80.71 (169,290) 83.12 Forfeited (c) (16,438) 73.95 (16,683) 78.40 Nonvested at December 31, 2023 374,367 (a) 73.29 347,283 77.29 Vested Awards Outstanding at December 31, 2023 70,766 155,708 (a) Includes 34,367 of awards that will be cash settled. (b) The performance shares are reflected at target payout level. (c) We account for forfeitures as they occur. Share-based liabilities paid relating to restricted stock units were $6 million, $3 million, and $4 million in 2023, 2022 and 2021, respectively. This includes cash used to settle restricted stock units of $3 million, $3 million, and $3 million in 2023, 2022 and 2021, respectively. Restricted stock units that are cash settled are classified as liability awards. All performance shares are classified as equity awards. Restricted Stock Units, Stock Grants, and Stock Units Restricted stock units are granted to officers and key employees and typically vest and settle in equal annual installments over a 4-year period after the grant date. Vesting is typically dependent upon continuous service during the vesting period. Beginning in 2022, restricted stock unit awards are issued in stock. Awards include a dividend equivalent feature that allows each award to accrue dividends and treat them as reinvested, from the date of grant until the applicable vesting date. If the award is forfeited the employee is not entitled to the accrued reinvested dividends on those shares. Awards granted to retirement-eligible employees will vest on a pro-rata basis upon the employee’s retirement. Prior to 2022, awardees typically elected to receive payment in either 100% stock, 100% cash, or 50% in cash and 50% in stock. Awards included a dividend equivalent feature that accrued dividend rights from the date of grant until the applicable vesting date, plus interest compounded quarterly. If the award was forfeited, the employee was not entitled to the accrued dividends on those shares. Awards granted to retirement-eligible employees typically vested upon the employee’s retirement. Compensation cost for restricted stock unit awards is based on the fair value of the award, with the fair value being the market price of our stock on the measurement date. Restricted stock unit awards that will be settled in cash are accounted for as liability awards, with compensation cost initially calculated on the date of grant using the Company’s closing stock price and remeasured at each balance sheet date. Restricted stock unit awards that will be settled in shares are accounted for as equity awards, with compensation cost calculated using the Company’s closing stock price on the date of grant. Compensation cost is recognized over the requisite service period based on the fair value of the award. Stock grants are issued to non-officer members of the Board of Directors. They may elect to receive the stock grant, or to defer receipt until a later date and receive stock units in lieu of the stock grant. Beginning in 2023, payments for stock units are issued in stock and include a dividend equivalent feature that allows each award to accrue dividends and treat them as reinvested, from the date of grant until the applicable vesting date. Prior to 2023, members of the Board of Directors who elected to defer could elect to receive payment in either 100% stock, 100% cash, or 50% in cash and 50% in stock. The stock units prior to 2023 included a dividend equivalent feature that accrues dividend rights from the date of grant to the date of payment, plus interest compounded quarterly. Performance Share Awards Performance share awards are granted to officers and key employees. The awards contain separate performance metric criteria that affect the number of shares that may be received if, after the end of a 3-year performance period, the performance criteria are met. Beginning in 2022, performance share awards contain three separate, unrelated performance criteria. The first performance criteria is based upon Pinnacle West’s total shareholder return (“TSR”) in relation to the TSR of other companies in a specified utility index (i.e., the TSR component). The second performance criteria is based upon Pinnacle West’s earnings per share (“EPS”) performance relative to an approved target (i.e., the EPS component). The third performance criteria is based upon APS’s clean MW installed of renewable or other carbon free resources compared to the approved target (i.e., the Clean component). The exact number of shares issued is calculated separately for each performance component and can vary from 0% to 200% of the target award for each separate performance criteria. Shares received include a dividend equivalent feature that treats accrued dividends as reinvested, from the date of grant until the date of payment, equal to the number of vested performance shares. If the award is forfeited or if the performance criteria are not achieved, the employee is not entitled to the dividends on those shares. Awards granted to retirement-eligible employees will vest on a pro-rata basis upon the employee’s retirement. Prior to 2022, performance share awards had two performance criteria. The first performance criteria was based upon non-financial performance metrics (i.e., the Metric component). The second performance criteria was based upon Pinnacle West’s TSR in relation to the TSR of other companies in a specified utility index (i.e., the TSR component). The exact number of shares issued will vary from 0% to 200% of the target award. Shares received included a dividend equivalent feature that allows accrued dividend rights from the date of grant until the date of payment, plus interest compounded quarterly, equal to the number of vested performance shares. If the award was forfeited, the employee was not entitled to the accrued dividends on those shares. Awards granted to retirement-eligible employees typically vested upon the employee’s retirement. Performance share awards are accounted for as equity awards, with compensation cost based on the fair value of the award on the grant date. Compensation cost relating to the EPS, Clean and Metric component of the respective awards is based on the Company’s closing stock price on the date of grant, with compensation cost recognized over the requisite service period based on the number of shares

Derivative Accounting

Derivative Accounting	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Accounting	Derivative Accounting Derivative financial instruments are used to manage exposure to commodity price and transportation costs of electricity, natural gas, emissions allowances, and interest rates. Risks associated with market volatility are managed by utilizing various physical and financial derivative instruments, including futures, forwards, options, and swaps. As part of our overall risk management program, we may use derivative instruments to hedge purchases and sales of electricity and natural gas. Derivative instruments that meet certain hedge accounting criteria may be designated as cash flow hedges and are used to limit our exposure to cash flow variability on forecasted transactions. The changes in market value of such instruments have a high correlation to price changes in the hedged transactions. Derivative instruments are also entered into for economic hedging purposes. While economic hedges may mitigate exposure to fluctuations in commodity prices, these instruments have not been designated as accounting hedges. Contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow are netted, which reduces both revenues and fuel and purchased power costs in our Consolidated Statements of Income, but does not impact our financial condition, net income, or cash flows. Our derivative instruments, excluding those qualifying for a scope exception, are recorded on the balance sheets as an asset or liability and are measured at fair value. See Note 12 for a discussion of fair value measurements. Derivative instruments may qualify for the normal purchases and normal sales scope exception if they require physical delivery, and the quantities represent those transacted in the normal course of business. Derivative instruments qualifying for the normal purchases and sales scope exception are accounted for under the accrual method of accounting and excluded from our derivative instrument discussion and disclosures below. Energy Derivatives For its regulated operations, APS defers for future rate treatment 100% of the unrealized gains and losses on energy derivatives pursuant to the PSA mechanism that would otherwise be recognized in income. Realized gains and losses on energy derivatives are deferred in accordance with the PSA to the extent the amounts are above or below the Base Fuel Rate. See Note 3. Gains and losses from energy derivatives in the following tables represent the amounts reflected in income before the effect of PSA deferrals. The following table shows the outstanding gross notional volume of energy derivatives, which represent both purchases and sales (does not reflect net position): Quantity Commodity Unit of Measure December 31, 2023 December 31, 2022 Power GWh 1,212 1,197 Gas Billion cubic feet 200 149 Gains and Losses from Energy Derivative Instruments For the years ended December 31, 2023, 2022 and 2021, APS had no energy derivative instruments in designated accounting hedging relationships. The following table provides information about gains and losses from energy derivative instruments not designated as accounting hedging instruments (dollars in thousands): Financial Statement Year Ended Commodity Contracts Location 2023 2022 2021 Net Gain (Loss) Recognized in Income Fuel and purchased power (a) $ (370,145) $ 307,287 $ 216,847 (a) Amounts are before the effect of PSA deferrals. Energy Derivative Instruments in the Consolidated Balance Sheets Our energy derivative transactions are typically executed under standardized or customized agreements, which include collateral requirements and, in the event of a default, would allow for the netting of positive and negative exposures associated with a single counterparty. Agreements that allow for the offsetting of positive and negative exposures associated with a single counterparty are considered master netting arrangements. Transactions with counterparties that have master netting arrangements are offset and reported net on the Consolidated Balance Sheets. Transactions that do not allow for offsetting of positive and negative positions are reported gross on the Consolidated Balance Sheets. We do not offset a counterparty’s current energy derivative contracts with the counterparty’s non-current energy derivative contracts, although our master netting arrangements would allow current and non-current positions to be offset in the event of a default. These types of transactions may include non-derivative instruments, derivatives qualifying for scope exceptions, trade receivables and trade payables arising from settled positions, and other forms of non-cash collateral (such as letters of credit). These types of transactions are excluded from the offsetting tables presented below. The following tables provide information about the fair value of APS’s risk management activities reported on a gross basis and the impacts of offsetting. These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of APS’s Consolidated Balance Sheets. As of December 31, 2023: Gross Amounts Net Other Amounts Current assets $ 8,497 $ (1,694) $ 6,803 $ 5 $ 6,808 Investments and other assets — — — — — Total assets 8,497 (1,694) 6,803 5 6,808 Current liabilities (85,736) 10,894 (74,842) (6,071) (80,913) Deferred credits and other (42,975) — (42,975) — (42,975) Total liabilities (128,711) 10,894 (117,817) (6,071) (123,888) Total $ (120,214) $ 9,200 $ (111,014) $ (6,066) $ (117,080) (a) All of our gross recognized derivative instruments were subject to master netting arrangements. (b) Includes cash collateral provided to counterparties of $9,200 thousand that is subject to offsetting. (c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument. Includes cash collateral received from counterparties of $6,071 thousand and cash margin provided to counterparties of $5 thousand. As of December 31, 2022: Gross Amounts Net Other Amounts Current assets $ 103,484 $ (15,808) $ 87,676 $ 28 $ 87,704 Investments and other assets 49,777 (5,383) 44,394 — 44,394 Total assets 153,261 (21,191) 132,070 28 132,098 Current liabilities (47,670) 15,808 (31,862) (5,835) (37,697) Deferred credits and other (9,223) 5,383 (3,840) — (3,840) Total liabilities (56,893) 21,191 (35,702) (5,835) (41,537) Total $ 96,368 $ — $ 96,368 $ (5,807) $ 90,561 (a) All of our gross recognized derivative instruments were subject to master netting arrangements. (b) No cash collateral has been provided to counterparties, or received from counterparties, that is subject to offsetting. (c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument. Includes cash collateral received from counterparties of $5,835 thousand and cash margin provided to counterparties of $28 thousand. Interest Rate Derivatives On October 19, 2022, Bright Canyon Energy entered into an interest rate swap to hedge the variable interest rate exposure relating to the credit agreement for the Los Alamitos project. The transaction qualified and had been designated as a cash flow hedge. The interest rate swap was included in the BCE Sale, and was assumed by Ameresco as part of the first stage of the closing. See Note 20. Prior to being transferred in the BCE Sale, the interest rate swap was in an asset position valued at $0.2 million. As of December 31, 2023, the interest rate swap has no impact on our Consolidated Balance Sheets. Credit Risk and Credit Related Contingent Features We are exposed to losses in the event of nonperformance or nonpayment by energy derivative counterparties and have risk management contracts with many energy derivative counterparties. As of December 31, 2023, we have no counterparties with positive exposures of greater than 10% of Pinnacle West’s risk management assets. Our risk management process assesses and monitors the financial exposure of all counterparties. Despite the fact that the great majority of our trading counterparties’ debt is rated as investment grade by the credit rating agencies, there is still a possibility that one or more of these counterparties could default, resulting in a material impact on consolidated earnings for a given period. Counterparties in the portfolio consist principally of financial institutions, major energy companies, municipalities, and local distribution companies. We maintain credit policies that we believe minimize overall credit risk to within acceptable limits. Determination of the credit quality of our counterparties is based upon a number of factors, including credit ratings and our evaluation of their financial condition. To manage credit risk, we employ collateral requirements and standardized agreements that allow for the netting of positive and negative exposures associated with a single counterparty. Valuation adjustments are established representing our estimated credit losses on our overall exposure to counterparties. Certain of our energy derivative instrument contracts contain credit-risk-related contingent features including, among other things, investment grade credit rating provisions, credit-related cross-default provisions, and adequate assurance provisions. Adequate assurance provisions allow a counterparty with reasonable grounds for uncertainty to demand additional collateral based on subjective events and/or conditions. For those energy derivative instruments in a net liability position, with investment grade credit contingencies, the counterparties could demand additional collateral if our debt credit rating were to fall below investment grade (below BBB- for Standard & Poor’s or Fitch or Baa3 for Moody’s). The following table provides information about our energy derivative instruments that have credit-risk-related contingent features (dollars in thousands): December 31, 2023 Aggregate fair value of derivative instruments in a net liability position $ 128,711 Cash collateral posted 9,200 Additional cash collateral in the event credit-risk related contingent features were fully triggered (a) 117,566 (a) This amount is after counterparty netting and includes those contracts which qualify for scope exceptions, which are excluded from the derivative details above. We also have energy related non-derivative instrument contracts with investment grade credit-related contingent features, which could also require us to post additional collateral of approximately $205 million if our debt credit ratings were to fall below investment grade.

Other Income and Other Expense

Other Income and Other Expense	12 Months Ended
	Dec. 31, 2023
Other Income and Expenses [Abstract]
Other Income and Other Expense	Other Income and Other Expense The following table provides detail of Pinnacle West’s Consolidated other income and other expense for 2023, 2022 and 2021 (dollars in thousands): 2023 2022 2021 Other income: Interest income $ 27,242 (a) $ 7,326 $ 6,726 Gain on Sale of BCE (Note 20) 6,205 — — Debt return on Four Corners SCR deferral (Note 3) — — 14,955 Debt return on Ocotillo modernization project (Note 3) — — 23,366 Miscellaneous 219 590 53 Total other income $ 33,666 $ 7,916 $ 45,100 Other expense: Non-operating costs $ (15,260) $ (18,619) $ (13,008) Investment gains (losses) — net (3,402) (20,537) (b) (1,367) Miscellaneous (6,394) (13,229) (c) (11,021) Total other expense $ (25,056) $ (52,385) $ (25,396) (a) The 2023 interest income is primarily related to PSA Interest. See Note 3. (b) The 2022 investment loss is primarily related to an impairment of PNW Power’s Clear Creek wind farm investment. See Note 10. (c) The 2022 miscellaneous amount includes donations of $7 million to the APS Foundation. Other Income and Other Expense - APS The following table provides detail of APS’s other income and other expense for 2023, 2022 and 2021 (dollars in thousands): 2023 2022 2021 Other income: Interest income $ 26,853 (a) $ 5,332 $ 4,692 Debt return on Four Corners SCR deferral (Note 3) — — 14,955 Debt return on Ocotillo modernization project (Note 3) — — 23,366 Miscellaneous 219 556 40 Total other income $ 27,072 $ 5,888 $ 43,053 Other expense: Non-operating costs $ (14,070) $ (15,579) $ (10,080) Miscellaneous (4,194) (10,529) (b) (8,817) Total other expense $ (18,264) $ (26,108) $ (18,897) (a) The 2023 interest income is primarily related to PSA Interest. See Note 3. (b)

Palo Verde Sale Leaseback Varia

Palo Verde Sale Leaseback Variable Interest Entities	12 Months Ended
	Dec. 31, 2023
Variable Interest Entities [Abstract]
Palo Verde Sale Leaseback Variable Interest Entities	Palo Verde Sale Leaseback Variable Interest Entities In 1986, APS entered into agreements with three separate VIE lessor trust entities in order to sell and lease back interests in Palo Verde Unit 2 and related common facilities. APS will retain the assets through 2033 under all three lease agreements. APS will be required to make payments relating to the three leases in total of approximately $21 million annually for the period 2024 through 2033. At the end of the lease period, APS will have the option to purchase the leased assets at their fair market value, extend the leases for up to two years, or return the assets to the lessors. The leases’ terms give APS the ability to utilize the assets for a significant portion of the assets’ economic life, and therefore provide APS with the power to direct activities of the VIEs that most significantly impact the VIEs’ economic performance. Predominantly due to the lease terms, APS has been deemed the primary beneficiary of these VIEs and therefore consolidates the VIEs. As a result of consolidation, we eliminate lease accounting and instead recognize depreciation expense, resulting in an increase in net income of $17 million for 2023, 2022 and 2021, respectively. The increase in net income is entirely attributable to the noncontrolling interests. Income attributable to Pinnacle West shareholders is not impacted by the consolidation. Our Consolidated Balance Sheets include the following amounts relating to the VIEs (dollars in thousands): December 31, 2023 December 31, 2022 Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation $ 86,426 $ 90,296 Equity-Noncontrolling interests 107,198 111,229 Assets of the VIEs are restricted and may only be used for payment to the noncontrolling interest holders. These assets are reported on our consolidated financial statements. APS is exposed to losses relating to these VIEs upon the occurrence of certain events that APS does not consider to be reasonably likely to occur. Under certain circumstances (for example, the NRC issuing specified violation orders with respect to Palo Verde or the occurrence of specified nuclear events), APS would be required to make specified payments to the VIEs’ noncontrolling equity participants and take title to the leased Unit 2 interests, which, if appropriate, may be required to be written-down in value. If such an event were to occur during the lease periods, APS may be required to pay the noncontrolling equity participants approximately $334 million beginning in 2024, and up to $501 million over the lease extension terms. For regulatory ratemaking purposes, the agreements continue to be treated as operating leases and, as a result, we have recorded a regulatory asset relating to the arrangements.

Investments in Nuclear Decommis

Investments in Nuclear Decommissioning Trusts and Other Special Use Funds	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Investments in Nuclear Decommissioning Trusts and Other Special Use Funds	Investments in Nuclear Decommissioning Trusts and Other Special Use Funds We have investments in debt and equity securities held in Nuclear Decommissioning Trusts, Coal Reclamation Escrow Account, and an Active Union Employee Medical Account. Investments in debt securities are classified as available-for-sale securities. We record both debt and equity security investments at their fair value on our Consolidated Balance Sheets. See Note 12 for a discussion of how fair value is determined and the classification of the investments within the fair value hierarchy. The investments in each trust or account are restricted for use and are intended to fund specified costs and activities as further described for each fund below. Nuclear Decommissioning Trusts — APS established external decommissioning trusts in accordance with NRC regulations to fund the future costs APS expects to incur to decommission Palo Verde. Third-party investment managers are authorized to buy and sell securities per stated investment guidelines. The trust funds are invested in fixed income securities and equity securities. Earnings and proceeds from sales and maturities of securities are reinvested in the trusts. Because of the ability of APS to recover decommissioning costs in rates, and in accordance with the regulatory treatment, APS has deferred realized and unrealized gains and losses (including credit losses) in other regulatory liabilities. Coal Reclamation Escrow Account — APS has investments restricted for the future coal mine reclamation funding related to Four Corners. This escrow account is primarily invested in fixed income securities. Earnings and proceeds from sales of securities are reinvested in the escrow account. Because of the ability of APS to recover coal reclamation costs in rates, and in accordance with the regulatory treatment, APS has deferred realized and unrealized gains and losses (including credit losses) in other regulatory liabilities. Activities relating to APS coal mine reclamation escrow account investments are included within the other special use funds in the table below. Active Union Employee Medical Account — APS has investments restricted for paying active union employee medical costs. These investments may be used to pay active union employee medical costs incurred in the current and future periods. In 2023 and 2022, APS was reimbursed $14 million and $15 million, respectively, for prior year active union employee medical claims from the active union employee medical account. The account is invested primarily in fixed income securities. In accordance with the ratemaking treatment, APS has deferred the unrealized gains and losses (including credit losses) in other regulatory liabilities. Activities relating to active union employee medical account investments are included within the other special use funds in the table below. APS The following tables present the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS’s nuclear decommissioning trusts and other special use fund assets (dollars in thousands): December 31, 2023 Fair Value Total Total Investment Type: Nuclear Decommissioning Trusts Other Special Use Funds Total Equity securities $ 420,680 $ 40,991 $ 461,671 $ 336,555 $ — Available for sale-fixed income securities 781,333 319,594 1,100,927 (a) 21,518 (40,868) Other (767) 2,196 1,429 (b) 39 — Total $ 1,201,246 $ 362,781 $ 1,564,027 $ 358,112 $ (40,868) (a) As of December 31, 2023, the amortized cost basis of these available-for-sale investments is $1,120 million. (b) Represents net pending securities sales and purchases. December 31, 2022 Fair Value Total Total Investment Type: Nuclear Decommissioning Trusts Other Special Use Funds Total Equity securities $ 487,240 $ 66,974 $ 554,214 $ 334,817 $ (267) Available for sale-fixed income securities 582,343 279,294 861,637 (a) 3,177 (68,795) Other 3,827 963 4,790 (b) — (29) Total $ 1,073,410 $ 347,231 $ 1,420,641 $ 337,994 $ (69,091) (a) As of December 31, 2022, the amortized cost basis of these available-for-sale investments is $927 million. (b) Represents net pending securities sales and purchases. The following table sets forth APS’s realized gains and losses relating to the sale and maturity of available-for-sale debt securities and equity securities, and the proceeds from the sale and maturity of these investment securities (dollars in thousands): Year Ended December 31, Nuclear Decommissioning Trusts Other Special Use Funds Total 2023 Realized gains $ 111,922 $ 172 $ 112,094 Realized losses $ (41,212) $ (568) $ (41,780) Proceeds from the sale of securities (a) $ 1,324,978 $ 354,744 $ 1,679,722 2022 Realized gains $ 9,017 $ 420 $ 9,437 Realized losses $ (40,239) $ — $ (40,239) Proceeds from the sale of securities (a) $ 979,639 $ 227,558 $ 1,207,197 2021 Realized gains $ 134,610 $ 49 $ 134,659 Realized losses $ (8,431) $ (7) $ (8,438) Proceeds from the sale of securities (a) $ 1,457,305 $ 263,661 $ 1,720,966 (a) Proceeds are reinvested in the nuclear decommissioning trusts and other special use funds, excluding amounts reimbursed to the Company for active union employee medical claims from the active union employee medical account. Fixed Income Securities Contractual Maturities The fair value of APS’s fixed income securities, summarized by contractual maturities, at December 31, 2023, is as follows (dollars in thousands): Nuclear Decommissioning Trusts Coal Reclamation Escrow Account Active Union Employee Medical Account Total Less than one year $ 26,057 $ 58,692 $ 36,857 $ 121,606 1 year – 5 years 225,891 46,120 152,761 424,772 5 years – 10 years 176,288 — 25,164 201,452 Greater than 10 years 353,097 — — 353,097 Total $ 781,333 $ 104,812 $ 214,782 $ 1,100,927

Changes in Accumulated Other Co

Changes in Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2023
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Changes in Accumulated Other Comprehensive Loss	Changes in Accumulated Other Comprehensive Loss The following table shows the changes in Pinnacle West’s consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component (dollars in thousands): Pension and Other Postretirement Benefits Derivative Instruments Total Balance at December 31, 2021 $ (53,885) $ (976) $ (54,861) OCI (loss) before reclassifications 17,550 1,873 19,423 Amounts reclassified from accumulated other comprehensive loss 4,003 (a) — 4,003 Balance at December 31, 2022 (32,332) 897 (31,435) OCI (loss) before reclassifications (4,420) 713 (3,707) Amounts reclassified from accumulated other comprehensive loss 1,998 (a) — 1,998 Balance at December 31, 2023 $ (34,754) $ 1,610 $ (33,144) (a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost. See Note 7. Changes in Accumulated Other Comprehensive Loss — APS The following table shows the changes in APS’s consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component (dollars in thousands): Pension and Other Postretirement Benefits Total Balance at December 31, 2021 $ (34,880) $ (34,880) OCI (loss) before reclassifications 15,646 15,646 Amounts reclassified from accumulated other comprehensive loss 3,638 (a) 3,638 Balance at December 31, 2022 (15,596) (15,596) OCI (loss) before reclassifications (3,383) (3,383) Amounts reclassified from accumulated other comprehensive loss 1,760 (a) 1,760 Balance at December 31, 2023 $ (17,219) $ (17,219) (a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost. See Note 7.

Sale of Bright Canyon Energy

Sale of Bright Canyon Energy	12 Months Ended
	Dec. 31, 2023
Discontinued Operations and Disposal Groups [Abstract]
Sale of Bright Canyon Energy	Sale of Bright Canyon Energy On August 4, 2023, Pinnacle West entered into a purchase and sale agreement pursuant to which we agreed to sell all of our equity interest in our wholly-owned subsidiary, BCE, to Ameresco. The transaction is accounted for as the sale of a business and was structured to close in multiple stages that were completed on January 12, 2024. Certain investments and assets that BCE previously held, including the TransCanyon joint venture and holdings in the two Tenaska wind farm investments, were not included in the BCE Sale and were instead transferred to PNW Power, a newly-formed, wholly-owned subsidiary of Pinnacle West. The BCE Sale did not include a $31 million equity bridge loan relating to BCE’s Los Alamitos project, which was paid in full by Pinnacle West on August 4, 2023. Other than these retained investments and the debt instrument, all BCE assets and liabilities were included in the BCE Sale and were transferred to Ameresco. The first stage of the BCE Sale closed on August 4, 2023, with the carrying value of net assets transferred to Ameresco totaling $44 million, which included a $36 million construction term loan. See Note 6. The assets and liabilities transferred in this stage related to the BCE Los Alamitos project and were previously primarily classified as construction work in progress and current maturities of long-term debt, respectively. Our Consolidated Income Statement for the year ended December 31, 2023, includes a pretax gain of $6 million relating to this stage of the BCE Sale reported within other income. Our Consolidated Balance Sheets as of December 31, 2023, includes a $28 million note receivable from Ameresco relating to this initial stage of the BCE Sale, which was received in full by Pinnacle West on January 29, 2024. As of December 31, 2023, our Consolidated Balance Sheets also include $35 million of assets classified as held for sale, relating to the remaining assets of BCE that transferred to Ameresco on January 12, 2024, in the second stage of the sale. These assets held for sale include BCE’s investment in the Kūpono Solar project, and other projects in various stages of development. The completion of the second stage of the BCE Sale was subject to various conditions precedent, including third-party consents which have been obtained. Prior to being classified as held for sale, these assets were primarily included in the other assets line item within the investments and other assets section on our Consolidated Balance Sheets. We measure assets held for sale at the lower of carrying value or fair value less cost to sell. For the year ended December 31, 2023, no impairment loss was recognized related to the assets classified as held for sale. The purchase and sale agreement, as amended, provided for Pinnacle West to purchase, from Ameresco, approximately $28 million of investment tax credits that were generated by the assets included in the BCE Sale. The tax credits were purchased and transferred to Pinnacle West on January 30, 2024.

New Accounting Standards

New Accounting Standards	12 Months Ended
	Dec. 31, 2023
Accounting Standards Update and Change in Accounting Principle [Abstract]
New Accounting Standards	New Accounting Standards ASU 2023-07, Segment Reporting: Improvements to Reportable Segment Disclosures In November 2023, a new accounting standard was issued that changes disclosures relating to reportable segments. The new guidance expands the disclosure requirements relating to reportable segments, including requiring entities to disclose information about a reportable segment’s significant expenses, among other changes. The amended guidance does not change how an entity identifies reportable segments or the accounting for segments. The new standard is effective for us, using a retrospective approach, on December 31, 2024, with early adoption permitted. The adoption of the new guidance may result in changes to our reportable segment disclosures, but will not impact our segment accounting or financial statement results. ASU 2023-09, Income Taxes: Improvements to Income Tax Disclosures In December 2023, a new accounting standard was issued that expands disclosures relating to income taxes. The changes require entities to include a tabular income tax rate reconciliation, disclose details on specific reconciliation categories and reconciling items, and disclose the amount of income taxes paid by jurisdiction, among other disclosure changes. The standard is effective for us on December 31, 2025, using a prospective approach, and may be early adopted. The adoption of the new guidance may result in changes to our income tax disclosures, but will not impact our accounting for income taxes or our financial statement results.

Schedule I - Condensed Financia

Schedule I - Condensed Financial Information of Registrant	12 Months Ended
	Dec. 31, 2023
Condensed Financial Information Disclosure [Abstract]
Schedule I - Condensed Financial Information of Registrant	PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (dollars in thousands) Year Ended December 31, 2023 2022 2021 Operating expenses $ 11,249 $ 8,850 $ 10,245 Other Equity in earnings of subsidiaries 539,962 500,042 628,916 Other income (expense) 2,823 (4,725) (4,919) Total 542,785 495,317 623,997 Interest expense 47,251 18,861 10,672 Income before income taxes 484,285 467,606 603,080 Income tax benefit (17,272) (15,996) (15,640) Net income attributable to common shareholders 501,557 483,602 618,720 Other comprehensive income (loss) — attributable to common shareholders (1,709) 23,426 7,935 Total comprehensive income — attributable to common shareholders $ 499,848 $ 507,028 $ 626,655 See Combined Notes to Consolidated Financial Statements. PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT CONDENSED BALANCE SHEETS (dollars in thousands) December 31, 2023 2022 ASSETS Current assets Cash and cash equivalents $ 9 $ — Accounts receivable 163,829 132,061 Income tax receivable 1,832 14,494 Assets held for sale- investment in subsidiaries 35,139 — Other current assets 28,379 288 Total current assets 229,188 146,843 Investments and other assets Investments in subsidiaries 7,369,159 7,105,789 Deferred income taxes 15,746 1,521 Other assets 22,839 23,153 Total investments and other assets 7,407,744 7,130,463 TOTAL ASSETS $ 7,636,932 $ 7,277,306 LIABILITIES AND EQUITY Current liabilities Accounts payable $ 8,176 $ 6,499 Accrued taxes 4,543 7,694 Common dividends payable 99,813 97,895 Short-term borrowings 76,650 15,720 Current maturities of long-term debt 625,000 — Operating lease liabilities 127 117 Other current liabilities 11,400 14,637 Total current liabilities 825,709 142,562 Long-term debt less current maturities 498,731 947,892 Pension liabilities 6,487 8,218 Operating lease liabilities 1,332 1,459 Other 19,811 17,299 Total deferred credits and other 27,630 26,976 COMMITMENTS AND CONTINGENCIES Common stock equity Common stock 2,744,491 2,719,735 Accumulated other comprehensive loss (33,144) (31,435) Retained earnings 3,466,317 3,360,347 Total Pinnacle West Shareholders’ equity 6,177,664 6,048,647 Noncontrolling interests 107,198 111,229 Total Equity 6,284,862 6,159,876 TOTAL LIABILITIES AND EQUITY $ 7,636,932 $ 7,277,306 See Combined Notes to Consolidated Financial Statements. PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT CONDENSED STATEMENTS OF CASH FLOWS (dollars in thousands) Year Ended December 31, 2023 2022 2021 Cash flows from operating activities Net income $ 501,557 $ 483,602 $ 618,720 Adjustments to reconcile net income to net cash provided by operating activities: Equity in earnings of subsidiaries — net (539,962) (500,042) (628,916) Gain on sale relating to BCE (6,423) — — Depreciation and amortization 76 76 93 Deferred income taxes (13,955) 17,256 (11,381) Accounts receivable (28,273) (8,535) 8,897 Accounts payable 1,839 3,431 (2,598) Accrued taxes and income tax receivables — net 9,505 (25,157) 16,079 Dividends received from subsidiaries 393,600 385,800 376,500 Other (14,201) 47,719 4,214 Net cash flow provided by operating activities 303,763 404,150 381,608 Cash flows from investing activities Proceeds from sale relating to BCE 23,400 — — Investments in subsidiaries (119,682) (186,630) (145,266) Repayments of loans from subsidiaries and other 6,526 14,308 4,017 Advances of loans to subsidiaries (59,349) (3,308) (12,256) Net cash flow used for investing activities (149,105) (175,630) (153,505) Cash flows from financing activities Issuance of long-term debt 175,000 300,000 300,000 Short-term debt repayments under revolving credit facility — — (19,000) Short-term borrowings and (repayments) — net 60,930 2,420 (136,700) Dividends paid on common stock (386,486) (378,881) (369,478) Repayment of long-term debt — (150,000) — Common stock equity issuance and purchases — net (4,093) (2,653) (2,350) Net cash flow used for financing activities (154,649) (229,114) (227,528) Net increase (decrease) in cash and cash equivalents 9 (594) 575 Cash and cash equivalents at beginning of year — 594 19 Cash and cash equivalents at end of year $ 9 $ — $ 594 See Combined Notes to Consolidated Financial Statements. PINNACLE WEST CAPITAL CORPORATION HOLDING COMPANY NOTES TO FINANCIAL STATEMENTS OF HOLDING COMPANY The Combined Notes to Consolidated Financial Statements in Part II, Item 8 should be read in conjunction with the Pinnacle West Capital Corporation Holding Company Financial Statements.

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation Pinnacle West is a holding company that conducts business through its subsidiaries, APS, El Dorado and PNW Power. APS, our wholly-owned subsidiary, is a vertically-integrated electric utility that provides either retail or wholesale electric service to substantially all of the state of Arizona, with the major exceptions of about one-half of the Phoenix metropolitan area, the Tucson metropolitan area and Mohave County in northwestern Arizona. APS accounts for essentially all of our revenues and earnings and is expected to continue to do so. El Dorado is a wholly-owned subsidiary that invests in energy-related and Arizona community-based ventures. PNW Power is a wholly-owned subsidiary that was created in September 2023 to hold certain investments in wind and transmission joint projects. See Note 20 for more information on PNW Power. BCE was a Pinnacle West subsidiary that was formed in 2014. On August 4, 2023, Pinnacle West entered into a purchase and sale agreement pursuant to which all of our equity interest in BCE was sold. The sale was completed on January 12, 2024. See Note 20 for more information relating to the sale of BCE. Pinnacle West’s Consolidated Financial Statements include the accounts of Pinnacle West and our subsidiaries: APS, El Dorado, BCE and PNW Power. APS’s Consolidated Financial Statements include the accounts of APS and certain VIEs relating to the Palo Verde sale leaseback. Intercompany accounts and transactions between the consolidated companies have been eliminated. We consolidate Variable Interest Entities (each a “VIE”) for which we are the primary beneficiary. We determine whether we are the primary beneficiary of a VIE through a qualitative analysis that identifies which variable interest holder has the controlling financial interest in the VIE. In performing our primary beneficiary analysis, we consider all relevant facts and circumstances, including the design and activities of the VIE, the terms of the contracts the VIE has entered into, and which parties participated significantly in the design or redesign of the entity. We continually evaluate our primary beneficiary conclusions to determine if changes have occurred which would impact our primary beneficiary assessments. We have determined that APS is the primary beneficiary of certain VIE lessor trusts relating to the Palo Verde sale leaseback, and therefore APS consolidates these entities. See Note 17 for additional information. We have determined that Pinnacle West is the primary beneficiary of a captive insurance protected cell VIE. As of December 31, 2023, the captive cell’s activities are insignificant to our consolidated financial statements. Our consolidated financial statements reflect all adjustments (consisting only of normal recurring adjustments, except as otherwise disclosed in the notes) that we believe are necessary for the fair presentation of our financial position, results of operations and cash flows for the periods presented.
Accounting Records and Use of Estimates	Accounting Records and Use of Estimates Our accounting records are maintained in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. To conform with the current year’s disaggregated presentation of significant changes in assets and liabilities and the aggregation of less significant changes in assets and liabilities, we made certain reclassifications for the year ended December 31, 2022, within the operating activities section of our Consolidated Statements of Cash Flows.
Regulatory Accounting	Regulatory Accounting APS is regulated by the ACC and the FERC. The accompanying financial statements reflect the rate-making policies of these commissions. As a result, we capitalize certain costs that would be included as expense in the current period by unregulated companies. Regulatory assets represent incurred costs that have been deferred because they are probable of future recovery in customer rates. Regulatory liabilities generally represent amounts collected in rates to recover costs expected to be incurred in the future or amounts collected in excess of costs incurred and are refundable to customers.
Electric Revenues	Electric Revenues Revenues primarily consist of activities that are classified as revenues from contracts with customers. Our electric revenues generally represent a single performance obligation delivered over time. We have elected to apply the practical expedient that allows us to recognize revenue based on the amount to which we have a right to invoice for services performed. We derive electric revenues primarily from sales of electricity to our regulated retail customers. Revenues related to the sale of electricity are generally recognized when service is rendered or electricity is delivered to customers. Unbilled revenues are estimated by applying an average revenue/kWh by customer class to the number of estimated kWhs delivered but not billed. Differences historically between the actual and estimated unbilled revenues are immaterial. We exclude sales taxes and franchise fees on electric revenues from both revenue and taxes other than income taxes. Revenues from our regulated retail customers and non-derivative instruments are reported on a gross basis on Pinnacle West’s Consolidated Statements of Income. In the electricity business, some contracts to purchase electricity are netted against other contracts to sell electricity. This is called a “book-out” and usually occurs for contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow. We net these book-outs, which reduces both wholesale revenues and fuel and purchased power costs. Certain cost recovery mechanisms may qualify as alternative revenue programs. For alternative revenue programs that meet specified accounting criteria, we recognize revenues when the specific events permitting billing of the additional revenues have been completed.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The allowance for doubtful accounts represents our best estimate of accounts receivable and accrued unbilled revenues that will ultimately be uncollectible due to credit loss risk. The allowance includes a write-off component that is calculated by applying an estimated write-off factor to retail electric revenues. The write-off factor used to estimate uncollectible accounts is based upon consideration of historical collections experience, the current and forecasted economic environment, changes to our collection policies, and management’s best estimate of future collections success. See Note 2.
Property, Plant and Equipment	Property, Plant and Equipment Utility plant is the term we use to describe the business property and equipment that supports electric service, consisting primarily of generation, transmission, and distribution facilities. We report utility plant at its original cost, which includes: • material and labor; • contractor costs; • capitalized leases; • construction overhead costs (where applicable); and • AFUDC. Property, plant and equipment balances and classes for APS are not materially different than Pinnacle West. We expense the costs of plant outages, major maintenance and routine maintenance as incurred. We charge retired utility plant to accumulated depreciation. Liabilities associated with the retirement of tangible long-lived assets are recognized at fair value as incurred and capitalized as part of the related tangible long-lived assets. Accretion of the liability due to the passage of time is an operating expense, and the capitalized cost is depreciated over the useful life of the long-lived asset. See Note 11 for additional information. APS records a regulatory liability for the excess that has been recovered in regulated rates over the amount calculated in accordance with guidance on accounting for AROs. APS believes it is probable it will recover in regulated rates, the costs calculated in accordance with this accounting guidance. We record depreciation and amortization on utility plant on a straight-line basis over the remaining useful life of the related assets. The approximate remaining average useful lives of our utility property at December 31, 2023, were as follows: • Steam generation — 11 years; • Nuclear plant — 25 years; • Other generation — 18 years; • Transmission — 38 years; • Distribution — 33 years; and • General plant — 7 years.
Asset Retirement Obligations	Asset Retirement Obligations APS has AROs for its Palo Verde nuclear facilities and certain other generation assets. The Palo Verde ARO primarily relates to final plant decommissioning. This obligation is based on the NRC’s requirements for disposal of radiated property or plant and agreements APS reached with the ACC for final decommissioning of the plant. The non-nuclear generation AROs primarily relate to requirements for removing portions of those plants at the end of the plant life or lease term and coal ash pond closures. Some of APS’s transmission and distribution assets have AROs because they are subject to right of way and easement agreements that require final removal. These agreements have a history of uninterrupted renewal that APS expects to continue. As a result, APS cannot reasonably estimate the fair value of the ARO related to such transmission and distribution assets. Additionally, APS has aquifer protection permits for some of its generation sites that require the closure of certain facilities at those sites.
Allowance for Funds Used During Construction	Allowance for Funds Used During Construction AFUDC represents the approximate net composite interest cost of borrowed funds and an allowed return on the equity funds used for construction of regulated utility plant. Both the debt and equity components of AFUDC are non-cash amounts within the Consolidated Statements of Income. Plant construction costs, including AFUDC, are recovered in authorized rates through depreciation when completed projects are placed into commercial operation. AFUDC was calculated by using a composite rate of 6.29% for 2023, 5.75% for 2022, and 6.75% for 2021. APS compounds AFUDC semi-annually and ceases to accrue AFUDC when construction work is completed and the property is placed in service. On June 30, 2020, FERC issued an order granting a waiver request related to the existing AFUDC rate calculation beginning March 1, 2020, through February 28, 2021. On February 23, 2021, this waiver was extended until September 30, 2021. On September 21, 2021, it was further extended until March 31, 2022. The order provided a simplified approach that companies may elect to implement in order to minimize the significant distorted effect on the AFUDC formula resulting from increased short-term debt financing during the COVID-19 pandemic. APS adopted this simplified approach to computing the AFUDC composite rate by using a simple average of the actual historical short-term debt balances for 2019, instead of current period short-term debt balances, and left all other aspects of the AFUDC formula composite rate calculation unchanged. This change impacted the AFUDC composite rate in 2021 and for the three-month period ended March 31, 2022. Furthermore, the change in the composite rate calculation did not impact our accounting treatment for these costs. The change did not have a material impact on our financial statements.
Materials and Supplies	Materials and Supplies APS values materials, supplies and fossil fuel inventory using a weighted-average cost method. APS materials, supplies and fossil fuel inventories are carried at the lower of weighted-average cost or net realizable value, unless evidence indicates that the weighted-average cost (even if in excess of market) will be recovered.
Fair Value Measurements	Fair Value Measurements We apply recurring fair value measurements to cash equivalents, derivative instruments, investments held in the nuclear decommissioning trust and other special use funds. On an annual basis, we apply fair value measurements to plan assets held in our retirement and other benefits plans. Due to the short-term nature of short-term borrowings, the carrying values of these instruments approximate fair value. Fair value measurements may also be applied on a nonrecurring basis to other assets and liabilities in certain circumstances such as impairments. We also disclose fair value information for our long-term debt, which is carried at amortized cost. See Note 6 for additional information. Fair value is the price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market which we can access for the asset or liability in an orderly transaction between willing market participants on the measurement date. Inputs to fair value may include observable and unobservable data. We maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. We determine fair market value using observable inputs such as actively-quoted prices for identical instruments when available. When actively-quoted prices are not available for the identical instruments, we use other observable inputs, such as prices for similar instruments, other corroborative market information, or prices provided by other external sources. For options, long-term contracts, and other contracts for which observable price data are not available, we use models and other valuation methods, which may incorporate unobservable inputs to determine fair market value. The use of models and other valuation methods to determine fair market value often requires subjective and complex judgment. Actual results could differ from the results estimated through application of these methods.
Derivative Accounting	Derivative Accounting We are exposed to the impact of market fluctuations in the commodity price and transportation costs of electricity, natural gas, coal and in interest rates. We manage risks associated with market volatility by utilizing various physical and financial instruments including futures, forwards, options, and swaps. As part of our overall risk management program, we may use derivative instruments to hedge purchases and sales of electricity and natural gas as well as interest rate risk. The changes in market value of such contracts have a high correlation to price changes in the hedged transactions. We also enter into derivative instruments for economic hedging purposes. Contracts that have the same terms (quantities, delivery points and delivery periods) and for which power does not flow are netted, which reduces both revenues and fuel and purchased power expenses in our Consolidated Statements of Income, but does not impact our financial condition, net income, or cash flows.
Loss Contingencies and Environmental Liabilities	Loss Contingencies and Environmental Liabilities Pinnacle West and APS are involved in certain legal and environmental matters that arise in the normal course of business. Contingent losses and environmental liabilities are recorded when it is determined that it is probable that a loss has occurred, and the amount of the loss can be reasonably estimated. When a range of the probable loss exists and no amount within the range is a better estimate than any other amount, Pinnacle West and APS record a loss contingency at the minimum amount in the range. Unless otherwise required by GAAP, legal fees are expensed as incurred.
Retirement Plans and Other Postretirement Benefits	Retirement Plans and Other Postretirement Benefits Pinnacle West sponsors a qualified defined benefit and account balance pension plan for the employees of Pinnacle West and its subsidiaries, in addition to a non-qualified pension plan. We also sponsor another postretirement benefit plan for the employees of Pinnacle West and its subsidiaries that provides medical and life insurance benefits to retired employees. Pension and other postretirement benefit expense are determined by actuarial valuations, based on assumptions that are evaluated annually. See Note 7 for additional information on pension and other postretirement benefits.
Nuclear Fuel	Nuclear Fuel APS amortizes nuclear fuel by using the unit-of-production method. The unit-of-production method is based on actual physical usage. APS divides the cost of the fuel by the estimated number of thermal units it expects to produce with that fuel. APS then multiplies that rate by the number of thermal units produced within the current period. This calculation determines the current period nuclear fuel expense.
Income Taxes	Income Taxes
Cash and Cash Equivalents	Cash and Cash Equivalents
Intangible Assets	Intangible Assets
Investments	Investments El Dorado holds investments in both debt and equity securities. Investments in debt securities are generally accounted for as held-to-maturity and investments in equity securities are accounted for using either the equity method (if significant influence) or the measurement alternative for investments without readily determinable fair values (if less than 20% ownership and no significant influence). PNW Power holds investments in equity securities. Investments in equity securities are accounted for using either the equity method (if significant influence) or the measurement alternative for investments without readily determinable fair values (if less than 20% ownership and no significant influence). Our investments in the nuclear decommissioning trusts, coal reclamation escrow accounts and active union employee medical account, are accounted for in accordance with guidance on accounting for investments in debt and equity securities. See Notes 12 and 18 for more information on these investments.
Leases	Leases We determine if an agreement is a lease at contract inception. A lease is defined as a contract, or part of a contract, that conveys the right to control the use of an identified asset for a period of time in exchange for consideration. To control the use of an identified asset an entity must have both a right to obtain substantially all of the benefits from the use of the asset and the right to direct the use of the asset. If we determine an agreement is a lease, and we are the lessee, we recognize a right-of-use lease asset and a lease liability at the lease commencement date. Lease liabilities are recognized based on the present value of the fixed lease payments over the lease term. To present value lease liabilities we use the implicit rate in the lease if the information is readily available, otherwise we use our incremental borrowing rate determined at lease commencement. Our incremental borrowing rate is based on the rate of interest we would have to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. When measuring right-of-use assets and lease liabilities we exclude variable lease payments, other than those that depend on an index or rate or are in-substance fixed payments. For short-term leases with terms of 12 months or less, we do not recognize a right-of-use lease asset or lease liability. We recognize operating lease expense using a straight-line pattern over the periods of use. APS enters into purchased power contracts that may contain leases. This occurs when a purchased power agreement designates a specific power plant or facility, APS obtains substantially all of the economic benefits from the use of the facility and has the right to direct the use of the facility. Purchased power lease contracts may also include energy storage facilities. Lease costs relating to purchased power lease contracts are reported in fuel and purchased power on the Consolidated Statements of Income and are subject to recovery under the PSA or RES. See Note 3 . We also may enter into lease agreements related to vehicles, office space, land, and other equipment. See Note 8 for information on our lease agreements.
Business Segments	Business Segments Pinnacle West’s reportable business segment is our regulated electricity segment, which consists of traditional regulated retail and wholesale electricity businesses (primarily electricity service to Native Load customers) and related activities and includes electricity generation, transmission, and distribution. All other segment activities are insignificant.
New Accounting Standards	New Accounting Standards ASU 2023-07, Segment Reporting: Improvements to Reportable Segment Disclosures In November 2023, a new accounting standard was issued that changes disclosures relating to reportable segments. The new guidance expands the disclosure requirements relating to reportable segments, including requiring entities to disclose information about a reportable segment’s significant expenses, among other changes. The amended guidance does not change how an entity identifies reportable segments or the accounting for segments. The new standard is effective for us, using a retrospective approach, on December 31, 2024, with early adoption permitted. The adoption of the new guidance may result in changes to our reportable segment disclosures, but will not impact our segment accounting or financial statement results. ASU 2023-09, Income Taxes: Improvements to Income Tax Disclosures In December 2023, a new accounting standard was issued that expands disclosures relating to income taxes. The changes require entities to include a tabular income tax rate reconciliation, disclose details on specific reconciliation categories and reconciling items, and disclose the amount of income taxes paid by jurisdiction, among other disclosure changes. The standard is effective for us on December 31, 2025, using a prospective approach, and may be early adopted. The adoption of the new guidance may result in changes to our income tax disclosures, but will not impact our accounting for income taxes or our financial statement results.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Schedule of Property, Plant and Equipment	Pinnacle West’s property, plant and equipment included in the December 31, 2023, and 2022 Consolidated Balance Sheets is composed of the following (dollars in thousands): Property, Plant and Equipment: 2023 2022 Generation $ 10,446,291 $ 9,563,145 Transmission 3,773,253 3,589,456 Distribution 8,448,293 7,951,867 General plant 1,543,330 1,347,678 Plant in service and held for future use 24,211,167 22,452,146 Accumulated depreciation and amortization (8,408,040) (7,929,878) Net 15,803,127 14,522,268 Construction work in progress 1,724,004 1,882,791 Palo Verde sale leaseback, net of accumulated depreciation 86,426 90,296 Intangible assets, net of accumulated amortization 267,110 258,880 Nuclear fuel, net of accumulated amortization 99,490 100,119 Total property, plant and equipment $ 17,980,157 $ 16,854,354
Schedule of Supplemental Cash Flow Information	The following table summarizes supplemental Pinnacle West cash flow information for each of the last three years (dollars in thousands): Year ended December 31, 2023 2022 2021 Cash paid during the period for: Income taxes, net of refunds $ 8,788 $ 46,227 $ 229 Interest, net of amounts capitalized 310,996 245,271 227,584 Significant non-cash investing and financing activities: Accrued capital expenditures $ 206,269 $ 114,999 $ 167,733 Dividends declared but not paid 99,813 97,895 95,988 BCE Sale non-cash consideration (Note 20) 28,262 — — The following table summarizes supplemental APS cash flow information for each of the last three years (dollars in thousands): Year ended December 31, 2023 2022 2021 Cash paid during the period for: Income taxes, net of refunds $ 21,734 $ 95,985 $ 19,783 Interest, net of amounts capitalized 267,261 227,159 217,749 Significant non-cash investing and financing activities: Accrued capital expenditures $ 206,269 $ 116,533 $ 167,657 Dividends declared but not paid 99,800 97,900 96,000

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of revenue	The following table provides detail of Pinnacle West’s consolidated revenue disaggregated by revenue sources (dollars in thousands): Year Ended December 31, 2023 2022 2021 Retail Electric Service Residential $ 2,289,196 $ 2,046,111 $ 1,913,324 Non-Residential 2,048,416 1,767,616 1,586,940 Wholesale Energy Sales 208,985 383,126 187,640 Transmission Services for Others 138,631 116,628 99,285 Other Sources 10,763 10,904 16,646 Total Operating Revenues $ 4,695,991 $ 4,324,385 $ 3,803,835
Schedule of allowance for doubtful accounts	The following table provides a rollforward of Pinnacle West’s allowance for doubtful accounts (dollars in thousands): Year Ended December 31, 2023 2022 2021 Allowance for doubtful accounts, balance at beginning of period $ 23,778 $ 25,354 $ 19,782 Bad debt expense 23,399 17,006 22,251 Actual write-offs (24,744) (18,582) (16,679) Allowance for doubtful accounts, balance at end of period $ 22,433 $ 23,778 $ 25,354

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2023
Regulated Operations [Abstract]
Schedule Of Capital Structure And Cost Of Capital, Regulatory Matter	the following proposed capital structure and costs of capital: Capital Structure Cost of Capital Long-term debt 48.07 % 3.85 % Common stock equity 51.93 % 10.25 % Weighted-average cost of capital 7.17 %
Schedule of changes in the Deferred Fuel and Purchased Power Regulatory Asset	The following table shows the changes in the deferred fuel and purchased power regulatory asset for 2023 and 2022 (dollars in thousands): Twelve Months Ended 2023 2022 Beginning balance $ 460,561 $ 388,148 Deferred fuel and purchased power costs — current period 549,877 291,992 Amounts charged to customers (547,243) (219,579) Ending balance $ 463,195 $ 460,561
Schedule of Regulatory Assets	The detail of regulatory assets is as follows (dollars in thousands): S December 31, Amortization Through 2023 2022 Pension (a) $ 696,476 $ 637,656 Deferred fuel and purchased power (b) (c) 2024 463,195 460,561 Income taxes — AFUDC equity 2053 189,058 179,631 Ocotillo deferral 2031 128,636 138,143 Deferred fuel and purchased power — mark-to-market (Note 16) 2026 120,214 — SCR deferral (e) 2038 89,477 97,624 Retired power plant costs 2033 83,536 98,692 Lease incentives (Note 8) (g) 46,615 — Income taxes — investment tax credit basis adjustment 2056 34,230 23,977 Deferred compensation 2036 33,972 33,660 Deferred property taxes 2027 32,488 41,057 Palo Verde VIEs (Note 17) 2046 20,772 20,933 Power supply adjustor-interest 2024 19,416 1,541 Active union medical trust (f) 12,747 18,226 Navajo coal reclamation 2026 10,883 13,862 Mead-Phoenix transmission line — contributions in aid of construction 2050 8,716 9,048 Loss on reacquired debt 2038 7,965 9,468 Four Corners cost deferral 2024 7,922 15,999 Tax expense adjustor mechanism (b) 2031 5,190 5,845 Lost fixed cost recovery (b) 2023 — 9,547 Other Various 4,528 6,630 Total regulatory assets (d) $ 2,016,036 $ 1,822,100 Less: current regulatory assets $ 625,757 $ 538,879 Total non-current regulatory assets $ 1,390,279 $ 1,283,221 (a) This asset represents the future recovery of pension benefit obligations and expense through retail rates. If these costs are disallowed by the ACC, this regulatory asset would be charged to OCI and result in lower future revenues. As a result of the 2019 Rate Case Decision, the amount authorized for inclusion in rate base was determined using an averaging methodology, which resulted in a reduced return in retail rates. The approved 2022 Rate Case ROO, as amended, allows for the full return on the pension asset in rate base. See Note 7 for further discussion. (b) See “Cost Recovery Mechanisms” discussion above. (c) Subject to a carrying charge. (d) There are no regulatory assets for which the ACC has allowed recovery of costs, but not allowed a return by exclusion from rate base. FERC rates are set using a formula rate as described in “Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters.” (e) See “Four Corners SCR Cost Recovery” discussion above. (f) Collected in retail rates. (g) Amortization periods vary based on specific terms of lease contract. See Note 8.
Schedule of Regulatory Liabilities	The detail of regulatory liabilities is as follows (dollars in thousands): December 31, Amortization Through 2023 2022 Excess deferred income taxes - ACC — Tax Cuts and Jobs Act (a) 2046 $ 930,344 $ 971,545 Excess deferred income taxes - FERC — Tax Cuts and Jobs Act (a) 2058 214,667 221,877 Asset retirement obligations 2057 392,383 354,002 Other postretirement benefits (d) 226,726 270,604 Removal costs (c) 94,368 106,889 Income taxes — deferred investment tax credit 2056 68,521 48,035 Income taxes — change in rates 2051 60,667 64,806 Four Corners coal reclamation 2038 55,917 52,592 Renewable energy standard (b) 2024 43,251 35,720 Spent nuclear fuel 2027 33,154 39,217 Sundance maintenance 2031 19,989 16,893 Demand side management (b) 2023 14,374 8,461 Property tax deferral (e) 2024 10,850 15,521 Tax expense adjustor mechanism (b) 2031 4,835 4,835 FERC transmission true up (b) 2025 1,869 22,895 Deferred fuel and purchased power — mark-to-market (Note 15) 2026 — 96,367 Other Various 3,873 3,092 Total regulatory liabilities $ 2,175,788 $ 2,333,351 Less: current regulatory liabilities $ 209,923 $ 271,575 Total non-current regulatory liabilities $ 1,965,865 $ 2,061,776 (a) For purposes of presentation on the Statement of Cash Flows, amortization of the regulatory liabilities for excess deferred income taxes are reflected as “Deferred income taxes” under Cash Flows From Operating Activities. (b) See “Cost Recovery Mechanisms” discussion above. (c) In accordance with regulatory accounting, APS accrues removal costs for its regulated assets, even if there is no legal obligation for removal. (d) See Note 7.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Unrecognized Tax Benefits Roll Forward	The following is a tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year that are included in accrued taxes and unrecognized tax benefits (dollars in thousands): Pinnacle West Consolidated APS Consolidated 2023 2022 2021 2023 2022 2021 Total unrecognized tax benefits, January 1 $ 43,097 $ 45,086 $ 45,655 $ 43,097 $ 45,086 $ 45,655 Additions for tax positions of the current year 1,473 1,399 3,305 1,473 1,399 3,305 Additions for tax positions of prior years 419 2,069 1,449 419 2,069 1,449 Reductions for tax positions of prior years for: Changes in judgment 661 (3,495) (2,659) 661 (3,495) (2,659) Settlements with taxing authorities — — — — — — Lapses of applicable statute of limitations (1,376) (1,962) (2,664) (1,376) (1,962) (2,664) Total unrecognized tax benefits, December 31 $ 44,274 $ 43,097 $ 45,086 $ 44,274 $ 43,097 $ 45,086
Schedule of Unrecognized Tax Benefits	Included in the balances of unrecognized tax benefits are the following tax positions that, if recognized, would decrease our effective tax rate (dollars in thousands): Pinnacle West Consolidated APS Consolidated 2023 2022 2021 2023 2022 2021 Tax positions, that if recognized, would decrease our effective tax rate $ 28,762 $ 28,246 $ 26,300 $ 28,762 $ 28,246 $ 26,300 Pinnacle West Consolidated APS Consolidated 2023 2022 2021 2023 2022 2021 Unrecognized tax benefit interest expense/(benefit) recognized $ 452 $ (139) $ (535) $ 452 $ (139) $ (535) Following are the total amount of accrued liabilities for interest recognized related to unrecognized benefits that could reverse and decrease our effective tax rate to the extent matters are settled favorably (dollars in thousands): Pinnacle West Consolidated APS Consolidated 2023 2022 2021 2023 2022 2021 Unrecognized tax benefit interest accrued $ 1,633 $ 1,181 $ 1,320 $ 1,633 $ 1,181 $ 1,320
Schedule Components of Income Tax Expense	The components of income tax expense are as follows (dollars in thousands): Pinnacle West Consolidated APS Consolidated Year Ended December 31, Year Ended December 31, 2023 2022 2021 2023 2022 2021 Current: Federal $ 21,272 $ 35,617 $ (5,041) $ 26,405 $ 103,349 $ 1,514 State 2,854 1,950 2,458 1,027 161 (11) Total current 24,126 37,567 (2,583) 27,432 103,510 1,503 Deferred: Federal 37,273 23,693 95,327 44,922 (31,860) 101,175 State 15,513 13,567 17,342 21,830 19,150 22,875 Total deferred 52,786 37,260 112,669 66,752 (12,710) 124,050 Income tax expense/(benefit) $ 76,912 $ 74,827 $ 110,086 $ 94,184 $ 90,800 $ 125,553
Schedule Comparison of Pretax Income from Continuing Operations at the Federal Income Tax Rate to Income Tax Expense - Continuing Operations	The following chart compares pretax income at the 21% statutory federal income tax rate to income tax expense (dollars in thousands): Pinnacle West Consolidated APS Consolidated Year Ended December 31, Year Ended December 31, 2023 2022 2021 2023 2022 2021 Federal income tax expense at statutory rate $ 125,095 $ 120,887 $ 156,666 $ 138,337 $ 132,920 $ 162,762 Increases (reductions) in tax expense resulting from: State income tax net of federal income tax benefit 18,024 17,740 22,656 19,832 19,000 23,339 State income tax credits net of federal income tax benefit (3,513) (5,482) (7,015) (1,775) (3,744) (5,277) Net operating loss carryback tax benefit — — (5,915) — — — Excess deferred income taxes — Tax Cuts and Jobs Act (36,558) (36,241) (36,558) (36,558) (36,241) (36,558) Allowance for equity funds used during construction (Note 1) (5,964) (4,629) (4,180) (5,964) (4,629) (4,180) Palo Verde VIE noncontrolling interest (Note 17) (3,617) (3,617) (3,617) (3,617) (3,617) (3,617) Investment tax credit amortization (9,495) (5,608) (7,620) (9,495) (5,608) (7,620) Federal production tax credit (8,441) (3,146) (3,064) (5,460) — — Other federal income tax credits (3,453) (7,721) (3,912) (2,803) (7,721) (3,912) Other 4,834 2,644 2,645 1,687 440 616 Income tax expense/(benefit) $ 76,912 $ 74,827 $ 110,086 $ 94,184 $ 90,800 $ 125,553
Schedule Components of the Net Deferred Income Tax Liability	The components of the net deferred income tax liability were as follows (dollars in thousands): Pinnacle West Consolidated APS Consolidated December 31, December 31, 2023 2022 2023 2022 DEFERRED TAX ASSETS Risk management activities $ 31,411 $ 8,826 $ 31,411 $ 8,826 Regulatory liabilities: Excess deferred income taxes — Tax Cuts and Jobs Act 283,161 295,014 283,161 295,014 Asset retirement obligation and removal costs 113,312 107,104 113,312 107,104 Unamortized investment tax credits 68,521 48,035 68,521 48,035 Other postretirement benefits 56,070 66,893 56,070 66,893 Other 39,857 62,915 39,857 62,915 Operating lease liabilities 316,067 184,030 315,670 182,663 Pension liabilities 33,294 33,674 29,918 30,436 Coal reclamation liabilities 45,505 44,312 45,505 44,312 Renewable energy incentives 17,261 19,948 17,261 19,948 Credit and loss carryforwards 43,940 37,647 3,031 13,654 Other 77,865 72,605 77,865 72,605 Total deferred tax assets 1,126,264 981,003 1,081,582 952,405 DEFERRED TAX LIABILITIES Plant-related (2,572,495) (2,518,164) (2,572,495) (2,518,164) Risk management activities (1,682) (32,648) (1,682) (32,648) Pension and other postretirement assets (78,853) (96,845) (78,297) (96,196) Other special use funds (56,550) (57,572) (56,550) (57,572) Operating lease right-of-use assets (316,067) (184,030) (315,670) (182,663) Regulatory assets: Allowance for equity funds used during construction (46,754) (44,405) (46,754) (44,405) Deferred fuel and purchased power (149,078) (114,232) (149,078) (114,232) Pension benefits (172,239) (157,629) (172,239) (157,629) Retired power plant costs (20,659) (24,397) (20,659) (24,397) Other (92,260) (103,023) (92,260) (103,023) Other (36,107) (32,479) (7,595) (7,123) Total deferred tax liabilities (3,542,744) (3,365,424) (3,513,279) (3,338,052) Deferred income taxes — net $ (2,416,480) $ (2,384,421) $ (2,431,697) $ (2,385,647)

Lines of Credit and Short-Ter_2

Lines of Credit and Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2023
Lines of Credit and Short-Term Borrowings
Schedule of Consolidated Credit Facilities and Amounts Available and Outstanding	The table below presents the consolidated credit facilities and the amounts available and outstanding (dollars in thousands): December 31, 2023 December 31, 2022 Pinnacle West APS Total Pinnacle West APS Total Commitments under Credit Facilities $ 200,000 $ 1,250,000 $ 1,450,000 $ 200,000 $ 1,000,000 $ 1,200,000 Outstanding short-term borrowings (76,650) (532,850) (609,500) (15,720) (325,000) (340,720) Amount of Credit Facilities Available $ 123,350 $ 717,150 $ 840,500 $ 184,280 $ 675,000 $ 859,280 Weighted-Average Commitment Fees 0.170% 0.120% 0.175% 0.125%

Long-Term Debt and Liquidity _2

Long-Term Debt and Liquidity Matters (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Components of Long-Term Debt on the Consolidated Balance Sheets	The following table presents the components of long-term debt on the Consolidated Balance Sheets outstanding (dollars in thousands): Maturity Interest December 31, Dates (a) Rates 2023 2022 APS Pollution control bonds: Variable 2029 (b) $ 163,975 $ 163,975 Total pollution control bonds 163,975 163,975 Senior unsecured notes 2024-2050 2.20%-6.88% 7,180,000 6,680,000 Unamortized discount (14,197) (14,548) Unamortized premium 11,162 12,368 Unamortized debt issuance cost (49,049) (48,266) Total APS long-term debt 7,291,891 6,793,529 Less current maturities 250,000 — Total APS long-term debt less current maturities 7,041,891 6,793,529 BCE Los Alamitos equity bridge loan (d) (d) — 27,575 Los Alamitos construction facility (d) (d) — 23,110 Unamortized debt issuance cost — (135) Total BCE long-term debt — 50,550 Less current maturities — 50,685 Total BCE long-term debt less current maturities — (135) Pinnacle West Senior unsecured notes 2025 1.30% 500,000 500,000 Term loans 2024 (c) 625,000 450,000 Unamortized discount (15) (25) Unamortized debt issuance cost (1,254) (2,083) Total Pinnacle West long-term debt 1,123,731 947,892 Less current maturities 625,000 — Total Pinnacle West long-term debt less current maturities 498,731 947,892 TOTAL LONG-TERM DEBT LESS CURRENT MATURITIES $ 7,540,622 $ 7,741,286 (a) This schedule does not reflect the timing of redemptions that may occur prior to maturities. (b) The weighted-average interest rate for the variable rate pollution control bonds was 4.11% at December 31, 2023, and 3.96% at December 31, 2022. (c) The weighted-average interest rate was 6.20% at December 31, 2023, and 5.10% at December 31, 2022. See additional details below. (d) On August 4, 2023, concurrent with the BCE Sale, the construction facility was transferred to Ameresco and the equity bridge loan was paid in full by Pinnacle West. See Note 20 and discussion below.
Schedule of Principal Payments Due on Pinnacle West's and APS's Total Long-Term Debt	The following table shows principal payments due on Pinnacle West’s and APS’s total long-term debt (dollars in thousands): Year Pinnacle West Consolidated APS Consolidated 2024 $ 875,000 $ 250,000 2025 800,000 300,000 2026 250,000 250,000 2027 300,000 300,000 2028 — — Thereafter 6,243,975 6,243,975 Total $ 8,468,975 $ 7,343,975
Schedule of Estimated Fair Value of Long-Term Debt, Including Current Maturities	The following table represents the estimated fair value of our long-term debt, including current maturities (dollars in thousands): As of As of Carrying Fair Value Carrying Fair Value Pinnacle West $ 1,123,731 $ 1,095,935 $ 947,892 $ 905,525 APS 7,291,891 6,459,718 6,793,529 5,629,491 BCE — — 50,550 50,685 Total $ 8,415,622 $ 7,555,653 $ 7,791,971 $ 6,585,701

Retirement Plans and Other Po_2

Retirement Plans and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Schedule of Net Periodic Benefit Costs and the Portion of these Costs Charged to Expense (Including Administrative Costs and Excluding Amounts Capitalized as Overhead Construction, Billed to Electric Plant Participants or Charged or Amortized to the Regulatory Asset)	The following table provides details of the plans’ net periodic benefit costs and the portion of these costs charged to expense (including administrative costs and excluding amounts capitalized as overhead construction or billed to electric plant participants) (dollars in thousands): Pension Plans Other Benefits Plans 2023 2022 2021 2023 2022 2021 Service cost-benefits earned during the period $ 39,461 $ 55,473 $ 61,236 $ 8,567 $ 16,470 $ 17,796 Non-service costs (credits): Interest cost on benefit obligation 153,561 107,492 98,566 22,509 17,491 16,513 Expected return on plan assets (182,938) (185,775) (202,628) (43,486) (46,042) (41,444) Amortization of: Prior service credit (a) — — — (37,789) (37,789) (37,705) Net actuarial (gain)/loss 38,420 17,515 15,948 (9,614) (12,835) (10,093) Net periodic benefit cost/(benefit) $ 48,504 $ (5,295) $ (26,878) $ (59,813) $ (62,705) $ (54,933) Portion of cost/(benefit) charged to expense $ 27,029 $ (16,431) $ (32,743) $ (43,408) $ (45,042) $ (38,657) (a) Prior-service costs or credits reflect the impact of modifications to the pension or postretirement plan benefits. The impact of these modifications is amortized over a period which reflects the demographics of the impacted population. In 2014, Pinnacle West made changes to the postretirement benefits offered to Medicare eligible retirees which resulted in prior-service credits. We have been amortizing these prior-serviced credits since 2015 with the last full-year amortization occurring in 2024.
Schedule of Changes in the Benefit Obligations and Funded Status	The following table shows the plans’ changes in the benefit obligations and funded status (dollars in thousands): Pension Plans Other Benefits Plans 2023 2022 2023 2022 Change in Benefit Obligation Benefit obligation at January 1 $ 2,809,529 $ 3,716,824 $ 409,461 $ 591,841 Service cost 39,461 55,473 8,567 16,470 Interest cost 153,561 107,492 22,509 17,491 Benefit payments (210,737) (212,565) (30,784) (30,913) Actuarial (gain) loss 116,249 (857,695) 20,681 (185,428) Benefit obligation at December 31 2,908,063 2,809,529 430,434 409,461 Change in Plan Assets Fair value of plan assets at January 1 2,829,485 3,812,041 652,287 872,435 Actual return/(loss) on plan assets 199,098 (787,874) 67,317 (193,807) Benefit payments (193,034) (194,682) (23,110) (26,341) Fair value of plan assets at December 31 2,835,549 2,829,485 696,494 652,287 Funded/(Underfunded) Status at December 31 $ (72,514) $ 19,956 $ 266,060 $ 242,826
Schedule of Projected Benefit Obligation and the Accumulated Benefit Obligation for Pension Plans with an Accumulated Obligation in Excess of Plan Assets	The following table shows information for pension plans with an accumulated obligation in excess of plan assets (dollars in thousands): As of December 31, 2023 2022 Accumulated benefit obligation $ 123,701 $ 126,759 Fair value of plan assets — — The following table shows information for pension plans with a projected benefit obligation in excess of plan assets (dollars in thousands): As of December 31, 2023 2022 Projected benefit obligation $ 129,891 $ 133,818 Fair value of plan assets — —
Schedule of Amounts Recognized on the Consolidated Balance Sheets	The following table shows the amounts recognized on the Consolidated Balance Sheets (dollars in thousands): Pension Plans Other Benefits Plans 2023 2022 2023 2022 Noncurrent asset $ 57,378 $ 153,773 $ 266,060 $ 242,826 Current liability (17,190) (17,531) — — Noncurrent liability (112,702) (116,286) — — Net amount recognized (funded status) $ (72,514) $ 19,956 $ 266,060 $ 242,826
Schedule of Accumulated Other Comprehensive Loss	The following table shows the details related to accumulated other comprehensive loss (gain) as of December 31, 2023, and 2022 (dollars in thousands): Pension Plans Other Benefits Plans 2023 2022 2023 2022 Net actuarial loss (gain) $ 743,003 $ 681,335 $ (188,630) $ (195,095) Prior service credit — — (39,054) (76,843) APS’s portion recorded as a regulatory (asset) liability (696,476) (637,656) 226,726 270,604 Income tax expense (benefit) (11,506) (10,797) 691 784 Accumulated other comprehensive loss (gain) $ 35,021 $ 32,882 $ (267) $ (550)
Schedule of Weighted-Average Assumptions Used for Both the Pension and Other Benefits to Determine Benefit Obligations and Net Periodic Benefit Costs	The following table shows the weighted-average assumptions used for both the pension and other benefits to determine benefit obligations and net periodic benefit costs: Benefit Obligations Benefit Costs 2023 2022 2023 2022 2021 Discount rate – pension plans 5.21 % 5.56 % 5.56 % 2.92 % 2.53 % Discount rate – other benefits plans 5.23 % 5.58 % 5.58 % 2.98 % 2.63 % Rate of compensation increase 4.52 % 4.57 % 4.57 % 4.00 % 4.00 % Expected long-term return on plan assets - pension plans N/A N/A 6.70 % 5.00 % 5.30 % Expected long-term return on plan assets - other benefit plans N/A N/A 6.80 % 5.35 % 4.90 % Initial healthcare cost trend rate (pre-65 participants) 6.25 % 6.50 % 6.50 % 6.00 % 6.50 % Ultimate healthcare cost trend rate (pre-65 participants) 4.75 % 4.75 % 4.75 % 4.75 % 4.75 % Number of years to ultimate trend rate (pre-65 participants) 5 6 5 3 4 Initial and ultimate healthcare cost trend rate (post-65 participants) 2.00 % 2.00 % 2.00 % 2.00 % 2.00 % Interest crediting rate – cash balance pension plans 4.54 % 4.50 % 4.50 % 4.50 % 4.50 %
Schedule of Fair Value of Pension Plan and Other Postretirement Benefit Plan Assets, by Asset Category	Based on the IPS, the target and actual allocation for the pension plan at December 31, 2023, are as follows: Target Allocation Actual Allocation Long-term fixed income assets 80 % 78 % Return-seeking assets 20 % 22 % Total 100 % 100 % The permissible range is within +/-5% of the target allocation shown in the above table, and also considers the plan’s funded status. The following table presents the additional target allocations, as a percent of total pension plan assets, for the return-seeking assets: Target Allocation Equities in US and other developed markets 12 % Equities in emerging markets 4 % Alternative investments 4 % Total 20 % Actual Allocation Long-term fixed income assets 62 % Return-seeking assets 38 % Total 100 % The fair value of Pinnacle West’s pension plan and other postretirement benefit plan assets at December 31, 2023, by asset category, are as follows (dollars in thousands): Level 1 Level 2 Other (a) Total Pension Plan: Fixed income securities: Corporate $ — $ 1,415,346 $ — $ 1,415,346 U.S. Treasury 622,273 — — 622,273 Other (b) — 135,184 — 135,184 Common stock equities (c) 150,657 — — 150,657 Mutual funds (d) 112,791 — — 112,791 Common and collective trusts: Equities — — 192,945 192,945 Real estate — — 140,613 140,613 Short-term investments and other (e) — — 65,740 65,740 Total $ 885,721 $ 1,550,530 $ 399,298 $ 2,835,549 Other Benefits: Fixed income securities: Corporate $ — $ 189,902 $ — $ 189,902 U.S. Treasury 207,665 — — 207,665 Other (b) — 8,372 — 8,372 Common stock equities (c) 139,952 — — 139,952 Mutual funds (d) 22,256 — — 22,256 Common and collective trusts: Equities — — 81,724 81,724 Real estate — — 20,001 20,001 Short-term investments and other (e) 21,146 — 5,476 26,622 Total $ 391,019 $ 198,274 $ 107,201 $ 696,494 (a) These investments primarily represent assets valued using NAV as a practical expedient and have not been classified in the fair value hierarchy. (b) This category consists primarily of debt securities issued by municipalities and asset backed securities. (c) This category primarily consists of U.S. common stock equities. (d) These funds invest in international common stock equities. (e) This category includes plan receivables and payables. Level 1 Level 2 Other (a) Total Pension Plan: Cash and cash equivalents $ 1,252 $ — $ — $ 1,252 Fixed income securities: Corporate — 1,374,810 — 1,374,810 U.S. Treasury 635,245 — — 635,245 Other (b) — 131,999 — 131,999 Common stock equities (c) 155,231 — — 155,231 Mutual funds (d) 101,557 — — 101,557 Common and collective trusts: Equities — — 181,912 181,912 Real estate — — 174,228 174,228 Partnerships — — 13,359 13,359 Short-term investments and other (e) — — 59,892 59,892 Total $ 893,285 $ 1,506,809 $ 429,391 $ 2,829,485 Other Benefits: Cash and cash equivalents $ 204 $ — $ — $ 204 Fixed income securities: Corporate — 166,879 — 166,879 U.S. Treasury 221,936 — — 221,936 Other (b) — 7,321 — 7,321 Common stock equities (c) 127,493 — — 127,493 Mutual funds (d) 18,824 — — 18,824 Common and collective trusts: Equities — — 73,956 73,956 Real estate — — 23,541 23,541 Short-term investments and other (e) 3,274 — 8,859 12,133 Total $ 371,731 $ 174,200 $ 106,356 $ 652,287 (a) These investments primarily represent assets valued using NAV as a practical expedient and have not been classified in the fair value hierarchy. (b) This category consists primarily of debt securities issued by municipalities. (c) This category primarily consists of U.S. common stock equities. (d) These funds invest in U.S. and international common stock equities. (e) This category includes plan receivables and payables.
Schedule of Estimated Future Benefit Payments, which Reflect Estimated Future Employee Service, for the Next Five Years and the Succeeding Five Years Thereafter	Benefit payments, which reflect estimated future employee service, for the next five years and the succeeding five years thereafter, are estimated to be as follows (dollars in thousands): Year Pension Plans Other Benefits Plans 2024 $ 244,772 $ 31,024 2025 226,748 30,446 2026 229,322 30,396 2027 226,906 30,024 2028 229,397 29,741 Years 2029-2033 1,136,944 149,312

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Schedule of Lease Costs	The following table provides information related to our lease costs (dollars in thousands): Year Ended December 31, 2023 2022 2021 Operating Lease Cost - Purchased Power & Energy Storage Lease Contracts $ 126,655 $ 104,001 $ 105,762 Operating Lease Cost - Land, Property, and Other Equipment 19,235 18,061 18,498 Total Operating Lease Cost 145,890 122,062 124,260 Variable Lease Cost (a) 135,007 122,040 118,969 Short-term Lease Cost 21,530 9,928 3,872 Total Lease Cost $ 302,427 $ 254,030 $ 247,101 (a) Primarily relates to purchased power lease contracts. The following tables provide other additional information related to operating lease liabilities (dollars in thousands): Year Ended December 31, 2023 2022 2021 Cash paid for amounts included in the measurement of lease liabilities — operating cash flows: $ 123,472 $ 118,463 $ 116,661 Right-of-use operating lease assets obtained in exchange for operating lease liabilities 602,301 (a) 16,990 500,582 December 31, 2023 December 31, 2022 Weighted average remaining lease term 10 years 7 years Weighted average discount rate (b) 4.53 % 2.21 % (a) Primarily relates to the two purchased power operating lease agreements that were modified in January 2023. (b)
Schedule of Maturities of Operating Lease Labilities	The following table provides information related to the maturity of our operating lease liabilities (dollars in thousands): December 31, 2023 Year Purchased Power & Energy Storage Lease Contracts Land, Property & Equipment Leases Total 2024 $ 108,201 $ 14,750 $ 122,951 2025 124,968 12,148 137,116 2026 138,692 9,826 148,518 2027 164,613 7,731 172,344 2028 168,410 5,401 173,811 Thereafter 835,813 64,090 899,903 Total lease commitments 1,540,697 113,946 1,654,643 Less imputed interest 334,693 41,878 376,571 Total lease liabilities $ 1,206,004 $ 72,068 $ 1,278,072

Jointly-Owned Facilities (Table

Jointly-Owned Facilities (Tables)	12 Months Ended
	Dec. 31, 2023
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Schedule Of APS's Interests In Jointly-owned Facilities Recorded On The Consolidated Balance Sheets	The following table shows APS’s interests in those jointly-owned facilities recorded on the Consolidated Balance Sheets at December 31, 2023 (dollars in thousands): Percent Plant in Accumulated Construction Generating facilities: Palo Verde Units 1 and 3 29.1 % $ 1,990,237 $ 1,087,614 $ 21,442 Palo Verde Unit 2 (a) 16.8 % 681,483 387,485 12,700 Palo Verde Common 28.0 % (b) 857,807 356,962 65,911 Palo Verde Sale Leaseback (a) 351,050 264,624 — Four Corners Generating Station 63.0 % 1,748,436 659,780 29,586 Cholla Common Facilities (c) 50.5 % 250,994 167,357 7,487 Transmission facilities: ANPP 500kV System 33.4 % (b) 136,145 58,252 4,801 Navajo Southern System 25.2 % (b) 87,185 36,743 550 Palo Verde — Yuma 500kV System 25.3 % (b) 24,057 7,912 432 Four Corners Switchyards 57.5 % (b) 84,279 21,918 161 Phoenix — Mead System 17.1 % (b) 39,772 20,679 257 Palo Verde — Rudd 500kV System 50.0 % 95,736 32,665 731 Morgan — Pinnacle Peak System 63.2 % (b) 117,080 26,990 229 Round Valley System 50.0 % 548 205 — Palo Verde — Morgan System 87.5 % (b) 268,629 40,962 8,053 Hassayampa — North Gila System 80.0 % 151,684 24,618 — Cholla 500kV Switchyard 85.7 % 8,445 2,760 — Saguaro 500kV Switchyard 60.0 % 21,627 14,060 17 Kyrene — Knox System 50.0 % 578 340 — Agua Fria Switchyard 10.0 % — — 77 (a) See Note 17. (b) Weighted-average of interests. (c)

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Estimated Coal Take-or-pay Commitments	The following table summarizes our estimated coal take-or-pay commitments (dollars in thousands): Year Ended December 31, 2024 2025 2026 2027 2028 Thereafter Coal take-or-pay commitments (a) $ 208,694 $ 229,111 $ 221,122 $ 200,256 $ 205,237 $ 647,377 (a) Total take-or-pay commitments are approximately $1.7 billion. The total net present value of these commitments is approximately $1.4 billion.
Schedule of Actual Take-or-pay Commitments	The following table summarizes actual amounts purchased under the coal contracts which include take-or-pay provisions for each of the last three years (dollars in thousands): Year Ended December 31, 2023 2022 2021 Total purchases $ 255,219 $ 305,502 $ 219,958

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2023
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Change in Asset Retirement Obligations	The following table shows the change in our AROs (dollars in thousands): 2023 2022 Asset retirement obligations at the beginning of year $ 797,762 $ 767,382 Changes attributable to: Accretion expense 44,269 41,240 Settlements (14,039) (10,860) Estimated cash flow revisions 135,323 — Newly incurred obligation 2,686 — Asset retirement obligations at the end of year $ 966,001 $ 797,762

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table presents the fair value at December 31, 2023, of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands): Balance at December 31, 2023 Level 1 Level 2 Level 3 Other Total ASSETS Cash equivalents $ 10 $ — $ — $ — $ 10 Risk management activities — derivative instruments: Commodity contracts — 1,881 6,616 (1,689) (a) 6,808 Nuclear decommissioning trust: Equity securities 11,064 — — (767) (b) 10,297 U.S. commingled equity funds — — — 409,616 (c) 409,616 U.S. Treasury debt 319,734 — — — 319,734 Corporate debt — 188,317 — — 188,317 Mortgage-backed securities — 208,306 — — 208,306 Municipal bonds — 59,323 — — 59,323 Other fixed income — 5,653 — — 5,653 Subtotal nuclear decommissioning trust 330,798 461,599 — 408,849 1,201,246 Other special use funds: Equity securities 40,991 — — 2,196 (b) 43,187 U.S. Treasury debt 319,594 — — — 319,594 Municipal bonds — — — — — Subtotal other special use funds 360,585 — — 2,196 362,781 Total assets $ 691,393 $ 463,480 $ 6,616 $ 409,356 $ 1,570,845 LIABILITIES Risk management activities — derivative instruments: Commodity contracts $ — $ (127,016) $ (1,695) $ 4,823 (a) $ (123,888) (a) Represents counterparty netting, margin, and collateral. See Note 15. (b) Represents net pending securities sales and purchases. (c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy. The following table presents the fair value at December 31, 2022, of our assets and liabilities that are measured at fair value on a recurring basis (dollars in thousands): Balance at December 31, 2022 Level 1 Level 2 Level 3 Other Total ASSETS Risk management activities — derivative instruments: Commodity contracts $ — $ 127,129 $ 26,132 $ (21,163) (a) $ 132,098 Interest rate swaps — 131 — — 131 Subtotal risk management activities - derivative instruments — 127,260 26,132 (21,163) 132,229 Nuclear decommissioning trust: Equity securities 14,658 — — 3,827 (b) 18,485 U.S. commingled equity funds — — — 472,582 (c) 472,582 U.S. Treasury debt 211,923 — — — 211,923 Corporate debt — 149,226 — — 149,226 Mortgage-backed securities — 147,938 — — 147,938 Municipal bonds — 64,881 — — 64,881 Other fixed income — 8,375 — — 8,375 Subtotal nuclear decommissioning trust 226,581 370,420 — 476,409 1,073,410 Other special use funds: Equity securities 66,974 — — 963 (b) 67,937 U.S. Treasury debt 275,267 — — — 275,267 Municipal bonds — 4,027 — — 4,027 Subtotal other special use funds 342,241 4,027 — 963 347,231 Total assets $ 568,822 $ 501,707 $ 26,132 $ 456,209 $ 1,552,870 LIABILITIES Risk management activities — derivative instruments: Commodity contracts $ — $ (25,874) $ (31,020) $ 15,357 (a) $ (41,537) Interest rate swaps — (909) — — (909) Subtotal risk management activities - derivative instruments — (26,783) (31,020) 15,357 (42,446) Total liabilities $ — $ (26,783) $ (31,020) $ 15,357 $ (42,446) (a) Represents counterparty netting, margin, and collateral. See Note 15. (b) Represents net pending securities sales and purchases. (c) Valued using NAV as a practical expedient and, therefore, are not classified in the fair value hierarchy. The following table shows the changes in fair value for our risk management activities’ assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs (dollars in thousands): Year Ended December 31, Commodity Contracts 2023 2022 Net derivative balance at beginning of period $ (4,888) $ (2,738) Total net gains (losses) realized/unrealized: Deferred as a regulatory asset or liability (70,214) (374) Settlements 69,706 (1,123) Transfers into Level 3 from Level 2 (1,289) (846) Transfers from Level 3 into Level 2 11,606 193 Net derivative balance at end of period $ 4,921 $ (4,888) Net unrealized gains included in earnings related to instruments still held at end of period $ — $ —
Schedule of Fair Value Measurement Inputs and Valuation Techniques	The following tables provide information regarding our significant unobservable inputs used to value our risk management derivative Level 3 instruments at December 31, 2023, and December 31, 2022: December 31, 2023 Valuation Significant Weighted-Average Commodity Contracts Assets Liabilities Technique Unobservable Input Range (b) Electricity: Forward Contracts (a) $ 6,587 $ 658 Discounted cash flows Electricity forward price (per MWh) $37.79 - $259.04 $ 158.08 Natural Gas: Forward Contracts (a) 29 1,037 Discounted cash flows Natural gas forward price (per MMBtu) $0.00 - $0.08 $ 0.03 Total $ 6,616 $ 1,695 (a) Includes swaps and physical and financial contracts. (b) Unobservable inputs were weighted by the relative fair value of the instrument. December 31, 2022 Valuation Significant Weighted-Average Commodity Contracts Assets Liabilities Technique Unobservable Input Range (b) Electricity: Forward Contracts (a) $ 26,132 $ 1,759 Discounted cash flows Electricity forward price (per MWh) $ 37.79 - $ 310.69 $ 163.92 Natural Gas: Forward Contracts (a) — 29,261 Discounted cash flows Natural gas forward price (per MMBtu) $(11.81) - $0.00 $ (5.08) Total $ 26,132 $ 31,020 (a) Includes swaps and physical and financial contracts. (b) Unobservable inputs were weighted by the relative fair value of the instrument.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of Earnings Per Weighted Average Common Share Outstanding	The following table presents the calculation of Pinnacle West’s basic and diluted earnings per share (in thousands, except per share amounts): 2023 2022 2021 Net income attributable to common shareholders $ 501,557 $ 483,602 $ 618,720 Weighted average common shares outstanding — basic 113,442 113,196 112,910 Net effect of dilutive securities: Contingently issuable performance shares and restricted stock units 362 220 282 Weighted average common shares outstanding — diluted 113,804 113,416 113,192 Earnings per weighted-average common share outstanding Net income attributable to common shareholders — basic $ 4.42 $ 4.27 $ 5.48 Net income attributable to common shareholders — diluted $ 4.41 $ 4.26 $ 5.47

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Restricted Stock Units, Stock Grants and Stock Units	The following table is a summary of awards granted and the weighted-average grant date fair value for each of the last three years: Restricted Stock Units, Stock Grants, and Stock Units (a) Performance Shares (b) 2023 2022 2021 2023 2022 2021 Units granted 192,295 174,791 152,345 202,562 208,736 161,840 Weighted-average grant date fair value $ 74.32 $ 69.66 $ 76.72 $ 79.61 $ 77.63 $ 82.42 (a) Units granted includes awards that will be cash settled of 0 in 2023, 0 in 2022, and 51,074 in 2021. See below for additional information on restricted stock unit grants. (b) Reflects the target payout level. The following table shows the change of nonvested awards: Restricted Stock Units, Stock Grants, and Stock Units Performance Shares Shares Weighted-Average Shares (b) Weighted-Average Nonvested at December 31, 2022 317,587 $ 73.91 330,694 $ 78.91 Granted 192,295 74.32 202,562 79.61 Vested (119,077) 80.71 (169,290) 83.12 Forfeited (c) (16,438) 73.95 (16,683) 78.40 Nonvested at December 31, 2023 374,367 (a) 73.29 347,283 77.29 Vested Awards Outstanding at December 31, 2023 70,766 155,708 (a) Includes 34,367 of awards that will be cash settled. (b) The performance shares are reflected at target payout level. (c)
Schedule of Nonvested Performance Shares	The following table is a summary of awards granted and the weighted-average grant date fair value for each of the last three years: Restricted Stock Units, Stock Grants, and Stock Units (a) Performance Shares (b) 2023 2022 2021 2023 2022 2021 Units granted 192,295 174,791 152,345 202,562 208,736 161,840 Weighted-average grant date fair value $ 74.32 $ 69.66 $ 76.72 $ 79.61 $ 77.63 $ 82.42 (a) Units granted includes awards that will be cash settled of 0 in 2023, 0 in 2022, and 51,074 in 2021. See below for additional information on restricted stock unit grants. (b) Reflects the target payout level. The following table shows the change of nonvested awards: Restricted Stock Units, Stock Grants, and Stock Units Performance Shares Shares Weighted-Average Shares (b) Weighted-Average Nonvested at December 31, 2022 317,587 $ 73.91 330,694 $ 78.91 Granted 192,295 74.32 202,562 79.61 Vested (119,077) 80.71 (169,290) 83.12 Forfeited (c) (16,438) 73.95 (16,683) 78.40 Nonvested at December 31, 2023 374,367 (a) 73.29 347,283 77.29 Vested Awards Outstanding at December 31, 2023 70,766 155,708 (a) Includes 34,367 of awards that will be cash settled. (b) The performance shares are reflected at target payout level. (c)

Derivative Accounting (Tables)

Derivative Accounting (Tables)	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Outstanding Gross Notional Amount of Derivatives, which Represents Both Purchases and Sales (Does Not Reflect Net Position)	The following table shows the outstanding gross notional volume of energy derivatives, which represent both purchases and sales (does not reflect net position): Quantity Commodity Unit of Measure December 31, 2023 December 31, 2022 Power GWh 1,212 1,197 Gas Billion cubic feet 200 149
Schedule of Gains and Losses from Derivative Instruments Not Designated as Accounting Hedges Instruments	The following table provides information about gains and losses from energy derivative instruments not designated as accounting hedging instruments (dollars in thousands): Financial Statement Year Ended Commodity Contracts Location 2023 2022 2021 Net Gain (Loss) Recognized in Income Fuel and purchased power (a) $ (370,145) $ 307,287 $ 216,847 (a) Amounts are before the effect of PSA deferrals.
Schedule of the Entity's Fair Value of Risk Management Activities Reported on a Gross Basis and the Impacts on Offsetting Liabilities	The following tables provide information about the fair value of APS’s risk management activities reported on a gross basis and the impacts of offsetting. These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of APS’s Consolidated Balance Sheets. As of December 31, 2023: Gross Amounts Net Other Amounts Current assets $ 8,497 $ (1,694) $ 6,803 $ 5 $ 6,808 Investments and other assets — — — — — Total assets 8,497 (1,694) 6,803 5 6,808 Current liabilities (85,736) 10,894 (74,842) (6,071) (80,913) Deferred credits and other (42,975) — (42,975) — (42,975) Total liabilities (128,711) 10,894 (117,817) (6,071) (123,888) Total $ (120,214) $ 9,200 $ (111,014) $ (6,066) $ (117,080) (a) All of our gross recognized derivative instruments were subject to master netting arrangements. (b) Includes cash collateral provided to counterparties of $9,200 thousand that is subject to offsetting. (c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument. Includes cash collateral received from counterparties of $6,071 thousand and cash margin provided to counterparties of $5 thousand. As of December 31, 2022: Gross Amounts Net Other Amounts Current assets $ 103,484 $ (15,808) $ 87,676 $ 28 $ 87,704 Investments and other assets 49,777 (5,383) 44,394 — 44,394 Total assets 153,261 (21,191) 132,070 28 132,098 Current liabilities (47,670) 15,808 (31,862) (5,835) (37,697) Deferred credits and other (9,223) 5,383 (3,840) — (3,840) Total liabilities (56,893) 21,191 (35,702) (5,835) (41,537) Total $ 96,368 $ — $ 96,368 $ (5,807) $ 90,561 (a) All of our gross recognized derivative instruments were subject to master netting arrangements. (b) No cash collateral has been provided to counterparties, or received from counterparties, that is subject to offsetting. (c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument. Includes cash collateral received from counterparties of $5,835 thousand and cash margin provided to counterparties of $28 thousand.
Schedule of the Entity's Fair Value of Risk Management Activities Reported on a Gross Basis and the Impacts on Offsetting Assets	The following tables provide information about the fair value of APS’s risk management activities reported on a gross basis and the impacts of offsetting. These amounts relate to commodity contracts and are located in the assets and liabilities from risk management activities lines of APS’s Consolidated Balance Sheets. As of December 31, 2023: Gross Amounts Net Other Amounts Current assets $ 8,497 $ (1,694) $ 6,803 $ 5 $ 6,808 Investments and other assets — — — — — Total assets 8,497 (1,694) 6,803 5 6,808 Current liabilities (85,736) 10,894 (74,842) (6,071) (80,913) Deferred credits and other (42,975) — (42,975) — (42,975) Total liabilities (128,711) 10,894 (117,817) (6,071) (123,888) Total $ (120,214) $ 9,200 $ (111,014) $ (6,066) $ (117,080) (a) All of our gross recognized derivative instruments were subject to master netting arrangements. (b) Includes cash collateral provided to counterparties of $9,200 thousand that is subject to offsetting. (c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument. Includes cash collateral received from counterparties of $6,071 thousand and cash margin provided to counterparties of $5 thousand. As of December 31, 2022: Gross Amounts Net Other Amounts Current assets $ 103,484 $ (15,808) $ 87,676 $ 28 $ 87,704 Investments and other assets 49,777 (5,383) 44,394 — 44,394 Total assets 153,261 (21,191) 132,070 28 132,098 Current liabilities (47,670) 15,808 (31,862) (5,835) (37,697) Deferred credits and other (9,223) 5,383 (3,840) — (3,840) Total liabilities (56,893) 21,191 (35,702) (5,835) (41,537) Total $ 96,368 $ — $ 96,368 $ (5,807) $ 90,561 (a) All of our gross recognized derivative instruments were subject to master netting arrangements. (b) No cash collateral has been provided to counterparties, or received from counterparties, that is subject to offsetting. (c) Represents cash collateral and cash margin that is not subject to offsetting. Amounts relate to non-derivative instruments, derivatives qualifying for scope exceptions, or collateral and margin posted in excess of the recognized derivative instrument. Includes cash collateral received from counterparties of $5,835 thousand and cash margin provided to counterparties of $28 thousand.
Schedule of Information about Derivative Instruments that have Credit-Risk-Related Contingent Features	The following table provides information about our energy derivative instruments that have credit-risk-related contingent features (dollars in thousands): December 31, 2023 Aggregate fair value of derivative instruments in a net liability position $ 128,711 Cash collateral posted 9,200 Additional cash collateral in the event credit-risk related contingent features were fully triggered (a) 117,566 (a) This amount is after counterparty netting and includes those contracts which qualify for scope exceptions, which are excluded from the derivative details above.

Other Income and Other Expense

Other Income and Other Expense (Tables)	12 Months Ended
	Dec. 31, 2023
Other Income and Expenses [Abstract]
Schedule of other income and other expense	The following table provides detail of Pinnacle West’s Consolidated other income and other expense for 2023, 2022 and 2021 (dollars in thousands): 2023 2022 2021 Other income: Interest income $ 27,242 (a) $ 7,326 $ 6,726 Gain on Sale of BCE (Note 20) 6,205 — — Debt return on Four Corners SCR deferral (Note 3) — — 14,955 Debt return on Ocotillo modernization project (Note 3) — — 23,366 Miscellaneous 219 590 53 Total other income $ 33,666 $ 7,916 $ 45,100 Other expense: Non-operating costs $ (15,260) $ (18,619) $ (13,008) Investment gains (losses) — net (3,402) (20,537) (b) (1,367) Miscellaneous (6,394) (13,229) (c) (11,021) Total other expense $ (25,056) $ (52,385) $ (25,396) (a) The 2023 interest income is primarily related to PSA Interest. See Note 3. (b) The 2022 investment loss is primarily related to an impairment of PNW Power’s Clear Creek wind farm investment. See Note 10. (c) The 2022 miscellaneous amount includes donations of $7 million to the APS Foundation. The following table provides detail of APS’s other income and other expense for 2023, 2022 and 2021 (dollars in thousands): 2023 2022 2021 Other income: Interest income $ 26,853 (a) $ 5,332 $ 4,692 Debt return on Four Corners SCR deferral (Note 3) — — 14,955 Debt return on Ocotillo modernization project (Note 3) — — 23,366 Miscellaneous 219 556 40 Total other income $ 27,072 $ 5,888 $ 43,053 Other expense: Non-operating costs $ (14,070) $ (15,579) $ (10,080) Miscellaneous (4,194) (10,529) (b) (8,817) Total other expense $ (18,264) $ (26,108) $ (18,897) (a) The 2023 interest income is primarily related to PSA Interest. See Note 3. (b)

Palo Verde Sale Leaseback Var_2

Palo Verde Sale Leaseback Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2023
Variable Interest Entities [Abstract]
Schedule of Amounts Relating to the VIEs Included in Consolidated Balance Sheets	Our Consolidated Balance Sheets include the following amounts relating to the VIEs (dollars in thousands): December 31, 2023 December 31, 2022 Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation $ 86,426 $ 90,296 Equity-Noncontrolling interests 107,198 111,229

Investments in Nuclear Decomm_2

Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Tables)	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of Fair Value of APS's Nuclear Decommissioning Trust Fund Assets	The following tables present the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS’s nuclear decommissioning trusts and other special use fund assets (dollars in thousands): December 31, 2023 Fair Value Total Total Investment Type: Nuclear Decommissioning Trusts Other Special Use Funds Total Equity securities $ 420,680 $ 40,991 $ 461,671 $ 336,555 $ — Available for sale-fixed income securities 781,333 319,594 1,100,927 (a) 21,518 (40,868) Other (767) 2,196 1,429 (b) 39 — Total $ 1,201,246 $ 362,781 $ 1,564,027 $ 358,112 $ (40,868) (a) As of December 31, 2023, the amortized cost basis of these available-for-sale investments is $1,120 million. (b) Represents net pending securities sales and purchases. December 31, 2022 Fair Value Total Total Investment Type: Nuclear Decommissioning Trusts Other Special Use Funds Total Equity securities $ 487,240 $ 66,974 $ 554,214 $ 334,817 $ (267) Available for sale-fixed income securities 582,343 279,294 861,637 (a) 3,177 (68,795) Other 3,827 963 4,790 (b) — (29) Total $ 1,073,410 $ 347,231 $ 1,420,641 $ 337,994 $ (69,091) (a) As of December 31, 2022, the amortized cost basis of these available-for-sale investments is $927 million. (b) Represents net pending securities sales and purchases.
Schedule of Realized Gains and Losses and Proceeds from the Sale of Securities by the Nuclear Decommissioning Trust Funds	The following table sets forth APS’s realized gains and losses relating to the sale and maturity of available-for-sale debt securities and equity securities, and the proceeds from the sale and maturity of these investment securities (dollars in thousands): Year Ended December 31, Nuclear Decommissioning Trusts Other Special Use Funds Total 2023 Realized gains $ 111,922 $ 172 $ 112,094 Realized losses $ (41,212) $ (568) $ (41,780) Proceeds from the sale of securities (a) $ 1,324,978 $ 354,744 $ 1,679,722 2022 Realized gains $ 9,017 $ 420 $ 9,437 Realized losses $ (40,239) $ — $ (40,239) Proceeds from the sale of securities (a) $ 979,639 $ 227,558 $ 1,207,197 2021 Realized gains $ 134,610 $ 49 $ 134,659 Realized losses $ (8,431) $ (7) $ (8,438) Proceeds from the sale of securities (a) $ 1,457,305 $ 263,661 $ 1,720,966 (a) Proceeds are reinvested in the nuclear decommissioning trusts and other special use funds, excluding amounts reimbursed to the Company for active union employee medical claims from the active union employee medical account.
Schedule of Fair Value of Fixed Income Securities, Summarized by Contractual Maturities	The fair value of APS’s fixed income securities, summarized by contractual maturities, at December 31, 2023, is as follows (dollars in thousands): Nuclear Decommissioning Trusts Coal Reclamation Escrow Account Active Union Employee Medical Account Total Less than one year $ 26,057 $ 58,692 $ 36,857 $ 121,606 1 year – 5 years 225,891 46,120 152,761 424,772 5 years – 10 years 176,288 — 25,164 201,452 Greater than 10 years 353,097 — — 353,097 Total $ 781,333 $ 104,812 $ 214,782 $ 1,100,927

Changes in Accumulated Other _2

Changes in Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2023
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Loss Including Reclassification Adjustments, by Component	The following table shows the changes in Pinnacle West’s consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component (dollars in thousands): Pension and Other Postretirement Benefits Derivative Instruments Total Balance at December 31, 2021 $ (53,885) $ (976) $ (54,861) OCI (loss) before reclassifications 17,550 1,873 19,423 Amounts reclassified from accumulated other comprehensive loss 4,003 (a) — 4,003 Balance at December 31, 2022 (32,332) 897 (31,435) OCI (loss) before reclassifications (4,420) 713 (3,707) Amounts reclassified from accumulated other comprehensive loss 1,998 (a) — 1,998 Balance at December 31, 2023 $ (34,754) $ 1,610 $ (33,144) (a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost. See Note 7. The following table shows the changes in APS’s consolidated accumulated other comprehensive loss, including reclassification adjustments, net of tax, by component (dollars in thousands): Pension and Other Postretirement Benefits Total Balance at December 31, 2021 $ (34,880) $ (34,880) OCI (loss) before reclassifications 15,646 15,646 Amounts reclassified from accumulated other comprehensive loss 3,638 (a) 3,638 Balance at December 31, 2022 (15,596) (15,596) OCI (loss) before reclassifications (3,383) (3,383) Amounts reclassified from accumulated other comprehensive loss 1,760 (a) 1,760 Balance at December 31, 2023 $ (17,219) $ (17,219) (a) These amounts primarily represent amortization of actuarial loss and are included in the computation of net periodic pension cost. See Note 7.

Summary of Significant Accoun_4

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, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2023 USD ($) $ / shares shares
Approximate remaining average useful lives of utility property
Depreciation		$ 669	$ 632	$ 575
Depreciation rates (as a percent)		2.98%	3.03%	2.87%
Allowance for Funds Used During Construction
Composite rate used to calculate AFUDC (as a percent)		6.29%	5.75%	6.75%
Income Taxes
Percent likelihood largest tax benefit amount is realized (greater than)		50%
Intangible Assets
Amortization expense		$ 90	$ 84	$ 80
Estimated amortization expense on existing intangible assets over the next five years
Estimated amortization expense, next year		90			$ 90
Estimated amortization expense, in two years		75			75
Estimated amortization expense, in three years		49			49
Estimated amortization expense, in four years		23			23
Estimated amortization expense, in five years		$ 11			$ 11
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%
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
Other Generation
Approximate remaining average useful lives of utility property
Average useful life		18 years			18 years
Transmission
Approximate remaining average useful lives of utility property
Average useful life		38 years			38 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

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Utility Plant and Depreciation [Line Items]
Net	$ 15,803,127	$ 14,522,268
Construction work in progress	1,724,004	1,882,791
Intangible assets, net of accumulated amortization	267,110	258,880
Nuclear fuel, net of accumulated amortization	99,490	100,119
Total property, plant and equipment	17,980,157	16,854,354
Electric Service
Utility Plant and Depreciation [Line Items]
Generation	10,446,291	9,563,145
Transmission	3,773,253	3,589,456
Distribution	8,448,293	7,951,867
General plant	1,543,330	1,347,678
Plant in service and held for future use	24,211,167	22,452,146
Accumulated depreciation and amortization	(8,408,040)	(7,929,878)
Net	15,803,127	14,522,268
Construction work in progress	1,724,004	1,882,791
Intangible assets, net of accumulated amortization	267,110	258,880
Nuclear fuel, net of accumulated amortization	99,490	100,119
Total property, plant and equipment	17,980,157	16,854,354
Electric Service | Variable Interest Entity
Utility Plant and Depreciation [Line Items]
Total property, plant and equipment	$ 86,426	$ 90,296

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash and Cash Equivalents [Line Items]
Income taxes, net of refunds	$ 8,788	$ 46,227	$ 229
Interest, net of amounts capitalized	310,996	245,271	227,584
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Accrued capital expenditures	206,269	114,999	167,733
Dividends declared but not paid	99,813	97,895	95,988
BCE Sale non-cash consideration	28,262	0	0
Arizona Public Service Company
Cash and Cash Equivalents [Line Items]
Income taxes, net of refunds	21,734	95,985	19,783
Interest, net of amounts capitalized	267,261	227,159	217,749
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Accrued capital expenditures	206,269	116,533	167,657
Dividends declared but not paid	$ 99,800	$ 97,900	$ 96,000

Revenue - Schedule of Disaggreg

Revenue - Schedule of Disaggregation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 4,695,991	$ 4,324,385	$ 3,803,835
Retail Electric Service | Residential
Disaggregation of Revenue [Line Items]
Total Operating Revenues	2,289,196	2,046,111	1,913,324
Retail Electric Service | Non-Residential
Disaggregation of Revenue [Line Items]
Total Operating Revenues	2,048,416	1,767,616	1,586,940
Wholesale Energy Sales
Disaggregation of Revenue [Line Items]
Total Operating Revenues	208,985	383,126	187,640
Transmission Services for Others
Disaggregation of Revenue [Line Items]
Total Operating Revenues	138,631	116,628	99,285
Other Sources
Disaggregation of Revenue [Line Items]
Total Operating Revenues	$ 10,763	$ 10,904	$ 16,646

Revenue - Additional Informatio

Revenue - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Operating revenues	$ 4,695,991	$ 4,324,385	$ 3,803,835
Regulatory cost recovery revenue	45,000	22,000	44,000
Electric and Transmission Service
Disaggregation of Revenue [Line Items]
Operating revenues	$ 4,651,000	$ 4,302,000	$ 3,760,000

Revenue - Allowance for Doubtfu

Revenue - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for doubtful accounts, balance at beginning of period	$ 23,778	$ 25,354	$ 19,782
Bad debt expense	23,399	17,006	22,251
Actual write-offs	(24,744)	(18,582)	(16,679)
Allowance for doubtful accounts, balance at end of period	$ 22,433	$ 23,778	$ 25,354

Regulatory Matters - Retail Rat

Regulatory Matters - Retail Rate Case Filing (Details) $ in Thousands

Feb. 22, 2024 USD ($)

Jan. 25, 2024 USD ($) $ / MWh

Jul. 26, 2023 USD ($) $ / kWh

Jul. 12, 2023 USD ($) $ / kWh

Jul. 11, 2023 $ / kWh

Jun. 14, 2023 USD ($)

Oct. 28, 2022 USD ($) $ / kWh

Jun. 30, 2022 USD ($)

Dec. 17, 2021 USD ($)

Oct. 27, 2021 USD ($)

Aug. 02, 2021 USD ($)

Feb. 23, 2024 USD ($)

Nov. 06, 2023 USD ($)

Nov. 05, 2023 USD ($)

Aug. 04, 2023 USD ($)

Aug. 03, 2023 USD ($)

Jun. 15, 2023 USD ($)

Mar. 06, 2023

Dec. 31, 2022 USD ($)

Nov. 30, 2022 USD ($)

Subsequent Event

Public Utilities, General Disclosures [Line Items]

Revenue increase (decrease)

$ 491,700

$ 523,100

ACC

Public Utilities, General Disclosures [Line Items]

Base fuel rate (in dollars per kWh) | $ / kWh

0.006

0.006

0.004

Revenue increase (decrease)

$ 281,900

$ 383,100

$ 282,700

$ 281,900

$ 251,000

Alternative revenue increase (decrease)

$ 312,000

Recommended return on equity, percentage

9.68%

10.25%

9.60%

Increment of fair value rate, percentage

0.50%

0.50%

0%

Alternative increment of fair value rate percentage

0.0075

Hypothetical capital structure of equity layer percentage

0.46

ACC | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Recommended return on equity, percentage

9.55%

9.55%

Increment of fair value rate, percentage

0.25%

0.25%

ACC | Coal Community Transition Plan | Navajo Nation, Electrification Projects

Public Utilities, General Disclosures [Line Items]

Amount funded by shareholders

$ 7,000

ACC | Coal Community Transition Plan | Navajo Nation, Electrification Projects | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Amount funded by shareholders

$ 1,000

ACC | Coal Community Transition Plan | Navajo Nation, Hopi Tribe | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Regulatory matters, amounts recoverable by rates

1,000

ACC | Coal Community Transition Plan | Navajo Nation | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Regulatory matters, amounts recoverable by rates

6,660

ACC | Coal Community Transition Plan | Navajo Nation, Hopi Reservation | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Regulatory matters, amounts recoverable by rates

1,250

ACC | Coal Community Transition Plan | Navajo County Communities | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Regulatory matters, amounts recoverable by rates

500

ACC | Coal Community Transition Plan | Navajo County Communities, CCT and Economic Development | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Amount funded by shareholders

1,100

ACC | Coal Community Transition Plan | Navajo Nation, Hopi Tribe for CCT and Economic Development | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Amount funded by shareholders

$ 1,250

ACC | Coal Community Transition Plan | Navajo and Hopi Tribes

Public Utilities, General Disclosures [Line Items]

Disbursement

$ 1,250

ACC | Arizona Public Service Company

Public Utilities, General Disclosures [Line Items]

Total revenue deficiency

$ 772,000

Revenue increase (decrease)

$ 376,200

$ 377,700

$ 383,100

Regulatory matters, customer bill impact rate

11.30%

11.10%

11.20%

Regulatory matters, no of basis penalty point

0.0020

20

0.0020

Reversal of basis point penalty

0.0020

ACC | Arizona Public Service Company | Retail Rate Case Filing with Arizona Corporation Commission

Public Utilities, General Disclosures [Line Items]

Approximate percentage of increase in average residential customer bill

13.60%

Rate matter, cost base rate

$ 10,500,000

Base fuel rate (in dollars per kWh) | $ / kWh

0.038321

Revenue increase (decrease)

$ (111,000)

Recommended return on equity, percentage

8.90%

8.70%

9.16%

Increment of fair value rate, percentage

0.30%

Reduction on equity percentage

0.03%

Effective fair value percentage

4.95%

ACC | Arizona Public Service Company | Retail Rate Case Filing with Arizona Corporation Commission | Subsequent Event

Public Utilities, General Disclosures [Line Items]

Base fuel rate (in dollars per kWh) | $ / MWh

0.006

Effective fair value percentage

4.39%

4.36%

Increases in annual revenue

$ 253,400

Increase to the typical residential customer’s bill

8%

Prepaid pension asset rate

5%

Pension and otherpost retirement and post employment benefit plans

5.35%

Retention of REAC

$ 1,900

Transfer to LFCR

$ 27,100

ACC | Arizona Public Service Company | Retail Rate Case Filing with Arizona Corporation Commission | Coal Community Transition Plan | Navajo Nation, Economic Development Organization

Public Utilities, General Disclosures [Line Items]

Disallowance of annual amortization percentage

15%

Amount funded by customers, term

10 years

Amount funded by customers

$ 50,000

ACC | Arizona Public Service Company | Retail Rate Case Filing with Arizona Corporation Commission | Coal Community Transition Plan | Navajo County Communities, Cholla Power Plant Closure

Public Utilities, General Disclosures [Line Items]

Amount funded by shareholders

$ 500

$ 5,000

Amount funded by shareholders, term

60 days

5 years

ACC | Arizona Public Service Company | Retail Rate Case Filing with Arizona Corporation Commission | Coal Community Transition Plan | Navajo Nation, Hopi Tribe

Public Utilities, General Disclosures [Line Items]

Amount funded by shareholders

$ 1,000

$ 1,675

Amount funded by shareholders, term

60 days

Amount not recoverable

$ 215,500

ACC | Arizona Public Service Company | Retail Rate Case Filing with Arizona Corporation Commission | Coal Community Transition Plan | Navajo Nation

Public Utilities, General Disclosures [Line Items]

Amount funded by shareholders

$ 10,000

Amount funded by shareholders, term

3 years

ACC | Arizona Public Service Company | Retail Rate Case Filing with Arizona Corporation Commission | Coal Community Transition Plan | Navajo Nation, Hopi Reservation

Public Utilities, General Disclosures [Line Items]

Amount funded by shareholders

$ 1,250

ACC | Arizona Public Service Company | Retail Rate Case Filing with Arizona Corporation Commission | Coal Community Transition Plan | Navajo Nation Reservation

Public Utilities, General Disclosures [Line Items]

Revenue increase (decrease)

(4,800)

Recommended return on equity, percentage

8.70%

Amount funded by shareholders

$ 1,250

Disallowance of plant investments

$ 215,500

Requested reversal of rate adjustment

$ 215,500

Lost revenue recovery

$ 59,600

Residential Utilities Consumer Office | ACC

Public Utilities, General Disclosures [Line Items]

Revenue increase (decrease)

$ 84,900

Recommended return on equity, percentage

8.20%

Increment of fair value rate, percentage

0%

Alternate recommended return on equity percentage

0.087

Minimum | ACC | Arizona Public Service Company

Public Utilities, General Disclosures [Line Items]

Annual increase in retail base rates

$ 460,000

Maximum | ACC

Public Utilities, General Disclosures [Line Items]

Increment of fair value rate, percentage

1%

Regulatory Matters - Capital St

Regulatory Matters - Capital Structure and Costs of Capital (Details) - Arizona Public Service Company	Oct. 28, 2022
Cost Of Capital [Abstract]
Requested Long-term debt cost of capital, percentage	3.85%
Requested equity cost of capital, percentage	10.25%
Requested weighted average cost of capital, percentage	7.17%
Retail Rate Case Filing with Arizona Corporation Commission
Capital Structure
Requested equity capital structure, percentage	51.93%
Retail Rate Case Filing with Arizona Corporation Commission | ACC
Capital Structure
Requested debt capital structure, percentage	48.07%

Regulatory Matters - Cost Recov

Regulatory Matters - Cost Recovery Mechanisms (Details)

6 Months Ended

12 Months Ended

Feb. 01, 2024 USD ($)

Oct. 11, 2023

Jul. 31, 2023 USD ($)

Jul. 01, 2023 USD ($) $ / KWH_Kilowatt_hour

Jun. 14, 2023 USD ($)

May 01, 2023 $ / kWh

Mar. 10, 2023 USD ($)

Feb. 23, 2023 USD ($) $ / kWh

Feb. 01, 2023 USD ($) $ / kWh

Jan. 06, 2023 USD ($)

Sep. 23, 2022 MW

Jul. 12, 2022 USD ($) $ / kWh

Jun. 01, 2022 USD ($)

Feb. 15, 2022 USD ($)

Feb. 01, 2022 USD ($) $ / kWh $ / KWH_Kilowatt_hour

Oct. 01, 2021 $ / kWh

Jun. 01, 2021 USD ($)

Feb. 15, 2021 USD ($)

Feb. 01, 2020 $ / kWh

Oct. 31, 2019 $ / KWH_Kilowatt_hour

Sep. 01, 2017

Jun. 30, 2021 program MW

Dec. 31, 2023 USD ($) storage

Dec. 31, 2022 USD ($) storage

Dec. 31, 2021 USD ($) storage

Dec. 31, 2017 $ / kWh

Dec. 31, 2017 $ / KWH_Kilowatt_hour

Nov. 30, 2023 USD ($)

Oct. 27, 2023 USD ($)

Jun. 30, 2023 USD ($)

May 31, 2023 USD ($)

Nov. 30, 2022 USD ($)

Jul. 01, 2022 USD ($)

Apr. 18, 2022 USD ($)

Dec. 17, 2021 USD ($)

Dec. 09, 2021 USD ($)

Jul. 01, 2021 USD ($)

Change in regulatory asset

Deferred fuel and purchased power costs — current period

$ 549,877,000

$ 291,992,000

$ 256,871,000

Amounts charged to customers

(547,243,000)

(219,579,000)

(44,557,000)

Arizona Public Service Company

Change in regulatory asset

Deferred fuel and purchased power costs — current period

549,877,000

291,992,000

256,871,000

Amounts charged to customers

$ (547,243,000)

$ (219,579,000)

$ (44,557,000)

Number of energy storage PPA | storage

9

1

4

Number of energy storage PPA, terminated | storage

1

Annual amount of approved equity infusions

$ 150,000,000

Increased in equity contributions

$ 500,000,000

Arizona Public Service Company | Damage from Fire, Explosion or Other Hazard

Change in regulatory asset

Past due balance threshold qualifying for payment extension

$ 75

ACC | Arizona Public Service Company

Settlement Agreement

Program term

18 years

Change in regulatory asset

Number of public utility programs | program

2

Solar power capacity | MW

80

Arizona Renewable Energy Standard and Tariff | ACC | Arizona Public Service Company

Settlement Agreement

Plan term

5 years

Arizona Renewable Energy Standard and Tariff 2018 | ACC | Arizona Public Service Company

Settlement Agreement

Amount of proposed budget

$ 95,100,000

$ 86,200,000

$ 100,500,000

$ 93,100,000

Arizona Renewable Energy Standard and Tariff 2018 | ACC | Arizona Public Service Company | Minimum

Change in regulatory asset

Authorized spending in capital costs

$ 20,000,000

Arizona Renewable Energy Standard and Tariff 2018 | ACC | Arizona Public Service Company | Maximum

Change in regulatory asset

Authorized spending in capital costs

$ 30,000,000

Arizona Renewable Energy Standard and Tariff 2018 | ACC | Arizona Public Service Company | Solar Communities

Settlement Agreement

Program term

3 years

Power Supply Adjustor (PSA) | ACC | Arizona Public Service Company

Change in regulatory asset

Beginning balance

$ 460,561,000

$ 388,148,000

Deferred fuel and purchased power costs — current period

549,877,000

291,992,000

Amounts charged to customers

(547,243,000)

(219,579,000)

Ending balance

$ 463,195,000

$ 460,561,000

$ 388,148,000

PSA rate (in dollars per kWh) | $ / kWh

0.019074

0.006

0.007544

Forward component Of PSA rate1 (in dollars per kWh) | $ / kWh

(0.005527)

0.004842

Historical component Of PSA rate1 (in dollars per kWh) | $ / kWh

0.013071

0.012386

Period to reduce balancing account

24 months

Reporting threshold of balancing account

$ 500,000

Transition component of PSA rate | $ / kWh

0.011530

Power Supply Adjustor (PSA) | ACC | Arizona Public Service Company | Cost Recovery Mechanisms

Change in regulatory asset

Maximum increase decrease in PSA rate (in dollars per kWh) | $ / kWh

0.004

PSA rate In prior years1 (in dollars per kWh) | $ / kWh

(0.004)

Retail Rate Case Filing with Arizona Corporation Commission | Arizona Public Service Company | Maximum

Change in regulatory asset

Fixed costs recoverable per power lost (in dollars per kWh) | $ / KWH_Kilowatt_hour

2.68

Retail Rate Case Filing with Arizona Corporation Commission | ACC | Arizona Public Service Company

Change in regulatory asset

Commercial customers, market pricing, threshold | MW

140

Retail Rate Case Filing with Arizona Corporation Commission | ACC | Arizona Public Service Company | Coal Community Transition Plan | Navajo Nation Reservation

Change in regulatory asset

Lost revenue recovery

$ 59,600,000

Demand Side Management Adjustor Charge 2022 | ACC | Arizona Public Service Company

Settlement Agreement

Amount of proposed budget

$ 78,400,000

Change in regulatory asset

Rate matter, increase (decrease) in proposed budget

$ 14,000,000

Demand Side Management Adjustor Charge 2023 | ACC | Arizona Public Service Company

Settlement Agreement

Amount of proposed budget

$ 88,000,000

$ 88,000,000

Environmental Improvement Surcharge | FERC | Arizona Public Service Company

Change in regulatory asset

Rate matters, environmental surcharge cap rate1 (in dollars per kWh) | $ / KWH_Kilowatt_hour

0.0005

Rate matters, environmental surcharge cap rate1, amount

$ 4,000,000

Rate matters, increase (decrease) In cost recovery

(10,700,000)

$ 14,700,000

Rate matters, increase (decrease) In cost recovery, excess Of annual amount

$ (7,500,000)

$ 3,300,000

Environmental Improvement Surcharge | FERC | Arizona Public Service Company | Subsequent Event

Change in regulatory asset

Rate matters, increase (decrease) In cost recovery

$ 15,300,000

Rate matters, increase (decrease) In cost recovery, excess Of annual amount

$ 11,300,000

Environmental Improvement Surcharge | FERC | Arizona Public Service Company | Minimum

Change in regulatory asset

Rate matters, environmental surcharge cap rate1, amount

$ 13,000,000

Environmental Improvement Surcharge | FERC | Arizona Public Service Company | Maximum

Change in regulatory asset

Rate matters, environmental surcharge cap rate1, amount

$ 15,000,000

Transmission rates, transmission cost adjustor and other transmission matters | FERC | Arizona Public Service Company

Change in regulatory asset

Rate matters, increase (decrease) In cost recovery

$ 34,700,000

$ (33,000,000)

$ 4,000,000

Rate matters, increase (decrease) in cost recovery, wholesale customer rates

20,700,000

6,400,000

3,200,000

Rate matters, increase (decrease) in cost recovery, retail customer rates

14,000,000

(26,600,000)

7,200,000

Rate matters, increase (decrease) In retail revenue requirements

$ 10,000,000

$ 2,400,000

$ 28,400,000

Lost Fixed Cost Recovery Mechanism | Arizona Public Service Company

Change in regulatory asset

Fixed costs recoverable per power lost (in dollars per kWh)

2.50

2.56

Rate matter cap percentage of retail revenue

1%

Amount of adjustment approved representing prorated sales losses pending approval

$ 68,700,000

$ 59,100,000

$ 38,500,000

Increase (decrease) In amount Of adjustment representing prorated sales losses

$ 32,500,000

$ 11,800,000

Amount of adjustment representing annual recovery

$ 9,600,000

Net Metering | ACC | Arizona Public Service Company

Change in regulatory asset

Rate matters, cost of service, resource comparison proxy method, maximum annual percentage decrease

10%

10%

10%

10%

Rate matters, cost of service for interconnected dg system customers, grandfathered period

20 years

Rate matters, cost of service for new customers, guaranteed export price period

10 years

Rate matter, request second-year energy price for exported energy1 (in dollars per kwh) | $ / kWh

0.0846

0.094

Third-year export energy price (in dollars per kWh) | $ / kWh

0.07619

Court Resolution Surcharge | ACC | Arizona Public Service Company

Change in regulatory asset

Court resolution surcharge (in dollars per kWh) | $ / KWH_Kilowatt_hour

0.00175

Lost revenue recovery

$ 59,600,000

2023 Transportation Electrification Plan | ACC | Arizona Public Service Company

Settlement Agreement

Amount of proposed budget

$ 5,000,000

Navajo Nation Reservation | Coal Community Transition Plan | Arizona Public Service Company | Coal Community Transition Plan

Change in regulatory asset

Lost revenue recovery collected

$ 9,400,000

Demand Side Management Adjustor Charge 2024 | ACC | Arizona Public Service Company

Settlement Agreement

Amount of proposed budget

$ 91,500,000

Regulatory Matters - Four Corne

Regulatory Matters - Four Corners, Cholla and Navajo Plant (Details) - Arizona Public Service Company - USD ($) $ in Millions		1 Months Ended
	Nov. 02, 2021	Sep. 30, 2018	Apr. 30, 2018	Dec. 31, 2023	Aug. 02, 2021
Coal Community Transition Plan | Navajo Nation, Economic Development Organization | Retail Rate Case Filing with Arizona Corporation Commission | ACC
Acquisition
Disallowance of annual amortization percentage					15%
Retired power plant costs
Acquisition
Net book value				$ 32.7
Navajo Plant
Acquisition
Net book value				43
Navajo Plant, Coal Reclamation Regulatory Asset
Acquisition
Net book value				$ 10.9
SCE | Four Corners Units 4 and 5
Acquisition
Settlement agreement, ACC approved rate adjustment, annualized customer impact		$ 58.5	$ 67.5
Disallowance of plant investments	$ 194
Cost deferrals	$ 215.5

Regulatory Matters - Schedule o

Regulatory Matters - Schedule of Regulatory Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Detail of regulatory assets
Total non-current regulatory assets	$ 2,016,036	$ 1,822,100
Less: current regulatory assets	625,757	538,879
Total non-current regulatory assets	1,390,279	1,283,221
Pension
Detail of regulatory assets
Total non-current regulatory assets	696,476	637,656
Deferred fuel and purchased power
Detail of regulatory assets
Total non-current regulatory assets	463,195	460,561
Income taxes — AFUDC equity
Detail of regulatory assets
Total non-current regulatory assets	189,058	179,631
Ocotillo deferral
Detail of regulatory assets
Total non-current regulatory assets	128,636	138,143
Deferred fuel and purchased power — mark-to-market (Note 16)
Detail of regulatory assets
Total non-current regulatory assets	120,214	0
SCR deferral
Detail of regulatory assets
Total non-current regulatory assets	89,477	97,624
Retired power plant costs
Detail of regulatory assets
Total non-current regulatory assets	83,536	98,692
Lease incentives (Note 8)
Detail of regulatory assets
Total non-current regulatory assets	46,615	0
Income taxes — investment tax credit basis adjustment
Detail of regulatory assets
Total non-current regulatory assets	34,230	23,977
Deferred compensation
Detail of regulatory assets
Total non-current regulatory assets	33,972	33,660
Deferred property taxes
Detail of regulatory assets
Total non-current regulatory assets	32,488	41,057
Palo Verde VIEs (Note 17)
Detail of regulatory assets
Total non-current regulatory assets	20,772	20,933
Power supply adjustor-interest
Detail of regulatory assets
Total non-current regulatory assets	19,416	1,541
Active union medical trust
Detail of regulatory assets
Total non-current regulatory assets	12,747	18,226
Navajo coal reclamation
Detail of regulatory assets
Total non-current regulatory assets	10,883	13,862
Mead-Phoenix transmission line — contributions in aid of construction
Detail of regulatory assets
Total non-current regulatory assets	8,716	9,048
Loss on reacquired debt
Detail of regulatory assets
Total non-current regulatory assets	7,965	9,468
Four Corners cost deferral
Detail of regulatory assets
Total non-current regulatory assets	7,922	15,999
Tax expense adjustor mechanism
Detail of regulatory assets
Total non-current regulatory assets	5,190	5,845
Lost fixed cost recovery
Detail of regulatory assets
Total non-current regulatory assets	0	9,547
Other
Detail of regulatory assets
Total non-current regulatory assets	$ 4,528	$ 6,630

Regulatory Matters - Schedule_2

Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Detail of regulatory liabilities
Total regulatory liabilities	$ 2,175,788	$ 2,333,351
Regulatory liabilities (Note 3)	209,923	271,575
Total non-current regulatory liabilities	1,965,865	2,061,776
Asset retirement obligations
Detail of regulatory liabilities
Total regulatory liabilities	392,383	354,002
Other postretirement benefits
Detail of regulatory liabilities
Total regulatory liabilities	226,726	270,604
Removal costs
Detail of regulatory liabilities
Total regulatory liabilities	94,368	106,889
Deferred fuel and purchased power — mark-to-market (Note 16)
Detail of regulatory liabilities
Total regulatory liabilities	0	96,367
Income taxes — change in rates
Detail of regulatory liabilities
Total regulatory liabilities	60,667	64,806
Four Corners coal reclamation
Detail of regulatory liabilities
Total regulatory liabilities	55,917	52,592
Income taxes — deferred investment tax credit
Detail of regulatory liabilities
Total regulatory liabilities	68,521	48,035
Spent nuclear fuel
Detail of regulatory liabilities
Total regulatory liabilities	33,154	39,217
Renewable energy program
Detail of regulatory liabilities
Total regulatory liabilities	43,251	35,720
FERC transmission true up
Detail of regulatory liabilities
Total regulatory liabilities	1,869	22,895
Property tax deferral
Detail of regulatory liabilities
Total regulatory liabilities	10,850	15,521
Sundance maintenance
Detail of regulatory liabilities
Total regulatory liabilities	19,989	16,893
Demand side management
Detail of regulatory liabilities
Total regulatory liabilities	14,374	8,461
Tax expense adjustor mechanism
Detail of regulatory liabilities
Total regulatory liabilities	4,835	4,835
Other
Detail of regulatory liabilities
Total regulatory liabilities	3,873	3,092
ACC | Excess deferred income taxes - ACC - Tax Cuts and Jobs Act
Detail of regulatory liabilities
Total regulatory liabilities	930,344	971,545
FERC | Excess deferred income taxes - ACC - Tax Cuts and Jobs Act
Detail of regulatory liabilities
Total regulatory liabilities	$ 214,667	$ 221,877

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Income Taxes
Income tax expense attributable to non controlling interests	$ 0
Interest expense to be received on the underpayment of income taxes	1
Increase (decrease) in deferred income taxes due to regulation adoption	12
Arizona Public Service Company
Income Taxes
Increase (decrease) in deferred income taxes due to regulation adoption	12
Federal
Income Taxes
State credit carryforwards net of federal benefit	56
Federal | Arizona Public Service Company
Income Taxes
State credit carryforwards net of federal benefit	15
State
Income Taxes
State credit carryforwards net of federal benefit	56
State | Arizona Public Service Company
Income Taxes
State credit carryforwards net of federal benefit	$ 15

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year
Total unrecognized tax benefits, beginning of the year	$ 43,097	$ 45,086	$ 45,655
Additions for tax positions of the current year	1,473	1,399	3,305
Additions for tax positions of prior years	419	2,069	1,449
Reductions for tax positions of prior years for:
Changes in judgment	661	(3,495)	(2,659)
Settlements with taxing authorities	0	0	0
Lapses of applicable statute of limitations	(1,376)	(1,962)	(2,664)
Total unrecognized tax benefits, end of the year	44,274	43,097	45,086
Arizona Public Service Company
Tabular reconciliation of the total amounts of unrecognized tax benefits, excluding interest and penalties, at the beginning and end of the year
Total unrecognized tax benefits, beginning of the year	43,097	45,086	45,655
Additions for tax positions of the current year	1,473	1,399	3,305
Additions for tax positions of prior years	419	2,069	1,449
Reductions for tax positions of prior years for:
Changes in judgment	661	(3,495)	(2,659)
Settlements with taxing authorities	0	0	0
Lapses of applicable statute of limitations	(1,376)	(1,962)	(2,664)
Total unrecognized tax benefits, end of the year	$ 44,274	$ 43,097	$ 45,086

Income Taxes - Summary of Unrec

Income Taxes - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax [Line Items]
Tax positions, that if recognized, would decrease our effective tax rate	$ 28,762	$ 28,246	$ 26,300
Unrecognized tax benefit interest expense/(benefit) recognized	452	(139)	(535)
Unrecognized tax benefit interest accrued	1,633	1,181	1,320
Arizona Public Service Company
Income Tax [Line Items]
Tax positions, that if recognized, would decrease our effective tax rate	28,762	28,246	26,300
Unrecognized tax benefit interest expense/(benefit) recognized	452	(139)	(535)
Unrecognized tax benefit interest accrued	$ 1,633	$ 1,181	$ 1,320

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 21,272	$ 35,617	$ (5,041)
State	2,854	1,950	2,458
Total current	24,126	37,567	(2,583)
Deferred:
Federal	37,273	23,693	95,327
State	15,513	13,567	17,342
Total deferred	52,786	37,260	112,669
Income tax expense/(benefit)	76,912	74,827	110,086
Arizona Public Service Company
Current:
Federal	26,405	103,349	1,514
State	1,027	161	(11)
Total current	27,432	103,510	1,503
Deferred:
Federal	44,922	(31,860)	101,175
State	21,830	19,150	22,875
Total deferred	66,752	(12,710)	124,050
Income tax expense/(benefit)	$ 94,184	$ 90,800	$ 125,553

Income Taxes - Effective Tax Ra

Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at statutory rate	$ 125,095	$ 120,887	$ 156,666
State income tax net of federal income tax benefit	18,024	17,740	22,656
State income tax credits net of federal income tax benefit	(3,513)	(5,482)	(7,015)
Net operating loss carryback tax benefit	0	0	(5,915)
Excess deferred income taxes — Tax Cuts and Jobs Act	(36,558)	(36,241)	(36,558)
Allowance for equity funds used during construction (Note 1)	(5,964)	(4,629)	(4,180)
Palo Verde VIE noncontrolling interest (Note 17)	(3,617)	(3,617)	(3,617)
Investment tax credit amortization	(9,495)	(5,608)	(7,620)
Federal production tax credit	(8,441)	(3,146)	(3,064)
Other federal income tax credits	(3,453)	(7,721)	(3,912)
Other	4,834	2,644	2,645
Income tax expense/(benefit)	76,912	74,827	110,086
Arizona Public Service Company
Income Tax Reconciliation Increases Reductions in Tax Expense [Abstract]
Federal income tax expense at statutory rate	138,337	132,920	162,762
State income tax net of federal income tax benefit	19,832	19,000	23,339
State income tax credits net of federal income tax benefit	(1,775)	(3,744)	(5,277)
Net operating loss carryback tax benefit	0	0	0
Excess deferred income taxes — Tax Cuts and Jobs Act	(36,558)	(36,241)	(36,558)
Allowance for equity funds used during construction (Note 1)	(5,964)	(4,629)	(4,180)
Palo Verde VIE noncontrolling interest (Note 17)	(3,617)	(3,617)	(3,617)
Investment tax credit amortization	(9,495)	(5,608)	(7,620)
Federal production tax credit	(5,460)	0	0
Other federal income tax credits	(2,803)	(7,721)	(3,912)
Other	1,687	440	616
Income tax expense/(benefit)	$ 94,184	$ 90,800	$ 125,553

Income Taxes - Components of De

Income Taxes - Components of Deferred Income Tax Liability (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
DEFERRED TAX ASSETS
Risk management activities	$ 31,411	$ 8,826
Regulatory liabilities:
Excess deferred income taxes — Tax Cuts and Jobs Act	283,161	295,014
Asset retirement obligation and removal costs	113,312	107,104
Unamortized investment tax credits	68,521	48,035
Other postretirement benefits	56,070	66,893
Other	39,857	62,915
Operating lease liabilities	316,067	184,030
Pension liabilities	33,294	33,674
Coal reclamation liabilities	45,505	44,312
Renewable energy incentives	17,261	19,948
Credit and loss carryforwards	43,940	37,647
Other	77,865	72,605
Total deferred tax assets	1,126,264	981,003
DEFERRED TAX LIABILITIES
Plant-related	(2,572,495)	(2,518,164)
Risk management activities	(1,682)	(32,648)
Pension and other postretirement assets	(78,853)	(96,845)
Other special use funds	(56,550)	(57,572)
Operating lease right-of-use assets	(316,067)	(184,030)
Regulatory assets:
Allowance for equity funds used during construction	(46,754)	(44,405)
Deferred fuel and purchased power	(149,078)	(114,232)
Pension benefits	(172,239)	(157,629)
Retired power plant costs	(20,659)	(24,397)
Other	(92,260)	(103,023)
Other	(36,107)	(32,479)
Total deferred tax liabilities	(3,542,744)	(3,365,424)
Deferred income taxes — net	(2,416,480)	(2,384,421)
Arizona Public Service Company
DEFERRED TAX ASSETS
Risk management activities	31,411	8,826
Regulatory liabilities:
Excess deferred income taxes — Tax Cuts and Jobs Act	283,161	295,014
Asset retirement obligation and removal costs	113,312	107,104
Unamortized investment tax credits	68,521	48,035
Other postretirement benefits	56,070	66,893
Other	39,857	62,915
Operating lease liabilities	315,670	182,663
Pension liabilities	29,918	30,436
Coal reclamation liabilities	45,505	44,312
Renewable energy incentives	17,261	19,948
Credit and loss carryforwards	3,031	13,654
Other	77,865	72,605
Total deferred tax assets	1,081,582	952,405
DEFERRED TAX LIABILITIES
Plant-related	(2,572,495)	(2,518,164)
Risk management activities	(1,682)	(32,648)
Pension and other postretirement assets	(78,297)	(96,196)
Other special use funds	(56,550)	(57,572)
Operating lease right-of-use assets	(315,670)	(182,663)
Regulatory assets:
Allowance for equity funds used during construction	(46,754)	(44,405)
Deferred fuel and purchased power	(149,078)	(114,232)
Pension benefits	(172,239)	(157,629)
Retired power plant costs	(20,659)	(24,397)
Other	(92,260)	(103,023)
Other	(7,595)	(7,123)
Total deferred tax liabilities	(3,513,279)	(3,338,052)
Deferred income taxes — net	$ (2,431,697)	$ (2,385,647)

Lines of Credit and Short-Ter_3

Lines of Credit and Short-Term Borrowings - Schedule of Credit Facilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pinnacle West
Lines of Credit and Short-Term Borrowings
Commitment fees (as a percent)	0.17%	0.175%
Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Commitment fees (as a percent)	0.12%	0.125%
Commercial paper
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities	$ 1,450,000	$ 1,200,000
Outstanding short-term borrowings	(609,500)	(340,720)
Amount of Credit Facilities Available	840,500	859,280
Commercial paper | Pinnacle West
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities	200,000	200,000
Outstanding short-term borrowings	(76,650)	(15,720)
Amount of Credit Facilities Available	123,350	184,280
Commercial paper | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities	1,250,000	1,000,000
Outstanding short-term borrowings	(532,850)	(325,000)
Amount of Credit Facilities Available	$ 717,150	$ 675,000

Lines of Credit and Short-Ter_4

Lines of Credit and Short-Term Borrowings - Additional Information (Details)	Feb. 09, 2024 USD ($)	Dec. 12, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 30, 2023	Apr. 10, 2023 USD ($) creditFacility	Apr. 09, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 17, 2020 USD ($)
Arizona Public Service Company | ACC
Debt Provisions
Percentage of APS's capitalization used in calculation of short-term debt authorization								7%
Required amount to be used in purchases of natural gas and power which is used in calculation of short-term debt authorization								$ 500,000,000
Term Loan | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Notes issued		$ 350,000,000
Debt instrument term		364 days
Term Loan | Arizona Public Service Company | Subsequent Event
Lines of Credit and Short-Term Borrowings
Loan amount drawn	$ 350,000,000
Term Loan | Arizona Public Service Company | SOFR
Lines of Credit and Short-Term Borrowings
Debt instrument, basis spread on variable rate		1%
Revolving credit facility | Revolving credit facility maturing May 2026 | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities					$ 500,000,000
Number of credit facilities | creditFacility					2
Revolving credit facility | Revolving credit facility maturing May 2026, facility two | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders					$ 400,000,000
Revolving credit facility | Revolving credit facility maturing May 2026, facility one | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders					400,000,000
Revolving credit facility | Revolving credit facility maturing in 2022 and 2023 | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Long-term line of credit			$ 0
Debt, weighted average interest rate				5.46%
Revolving credit facility | Revolving Credit Facility Maturing April 2028 | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities					1,250,000,000
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders					1,650,000,000
Letter of Credit | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Outstanding letters of credit			27,000,000
Letter of Credit | Revolving Credit Facility Maturing April 2028 | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Outstanding letters of credit			0
Commercial paper
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities			1,450,000,000				$ 1,200,000,000
Long-term line of credit			609,500,000				340,720,000
Commercial paper | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities			1,250,000,000				1,000,000,000
Long-term line of credit			532,850,000				325,000,000
Maximum commercial paper support available under credit facility					1,000,000,000	$ 750,000,000
Commercial paper | Revolving Credit Facility Maturing April 2028 | Arizona Public Service Company
Lines of Credit and Short-Term Borrowings
Commercial paper			533,000,000
Pinnacle West | Revolving credit facility | Revolving credit facility maturing May 2026
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities					200,000,000
Pinnacle West | Revolving credit facility | Revolving Credit Facility Maturing April 2028
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities					200,000,000
Maximum borrowing capacity on credit facility upon satisfaction of certain conditions and consent of lenders					$ 300,000,000
Long-term line of credit			0
Pinnacle West | Letter of Credit | Revolving Credit Facility Maturing April 2028
Lines of Credit and Short-Term Borrowings
Outstanding letters of credit			0
Pinnacle West | Commercial paper
Lines of Credit and Short-Term Borrowings
Commitments under Credit Facilities			200,000,000				200,000,000
Long-term line of credit			76,650,000				$ 15,720,000
Pinnacle West | Commercial paper | Revolving Credit Facility Maturing April 2028
Lines of Credit and Short-Term Borrowings
Commercial paper			$ 77,000,000
Debt, weighted average interest rate			5.47%

Long-Term Debt and Liquidity _3

Long-Term Debt and Liquidity Matters - Components of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Long-Term Debt and Liquidity Matters [Line Items]
Total long-term debt	$ 8,415,622	$ 7,791,971
Long-term debt less current maturities (Note 6)	7,540,622	7,741,286
Pinnacle West
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	8,468,975
Unamortized discount	(15)	(25)
Unamortized debt issuance cost	(1,254)	(2,083)
Total long-term debt	1,123,731	947,892
Less current maturities	625,000	0
Total long-term debt less current maturities	498,731	947,892
Long-term debt less current maturities (Note 6)	498,731	947,892
Arizona Public Service Company
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	7,343,975
Unamortized discount	(14,197)	(14,548)
Unamortized premium	11,162	12,368
Unamortized debt issuance cost	(49,049)	(48,266)
Total long-term debt	7,291,891	6,793,529
Less current maturities	250,000	0
Total long-term debt less current maturities	7,041,891	6,793,529
Long-term debt less current maturities (Note 6)	7,041,891	6,793,529
Bright Canyon Energy Corporation
Long-Term Debt and Liquidity Matters [Line Items]
Los Alamitos equity bridge loan	0	27,575
Los Alamitos construction facility	0	23,110
Unamortized debt issuance cost	0	(135)
Total long-term debt	0	50,550
Less current maturities	0	50,685
Total long-term debt less current maturities	0	(135)
Pollution Control Bonds - Variable | Arizona Public Service Company
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	$ 163,975	$ 163,975
Weighted-average interest rate (as a percent)	4.11%	3.96%
Total Pollution Control Bonds | Arizona Public Service Company
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	$ 163,975	$ 163,975
Senior Unsecured Notes | Pinnacle West
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	$ 500,000	500,000
Interest rate (as a percent)	1.30%
Senior Unsecured Notes | Arizona Public Service Company
Long-Term Debt and Liquidity Matters [Line Items]
Gross long-term debt	$ 7,180,000	6,680,000
Senior Unsecured Notes | Arizona Public Service Company | Minimum
Long-Term Debt and Liquidity Matters [Line Items]
Interest rate (as a percent)	2.20%
Senior Unsecured Notes | Arizona Public Service Company | Maximum
Long-Term Debt and Liquidity Matters [Line Items]
Interest rate (as a percent)	6.88%
Term Loan | Pinnacle West
Long-Term Debt and Liquidity Matters [Line Items]
Term loans	$ 625,000	$ 450,000
Term Loan | Arizona Public Service Company
Long-Term Debt and Liquidity Matters [Line Items]
Weighted-average interest rate (as a percent)	6.20%	5.10%

Long-Term Debt and Liquidity _4

Long-Term Debt and Liquidity Matters - Future Principal Payments (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Arizona Public Service Company
Principal payments due on long-term debt
2024	$ 250,000
2025	300,000
2026	250,000
2027	300,000
2028	0
Thereafter	6,243,975
Total	7,343,975
Pinnacle West
Principal payments due on long-term debt
2024	875,000
2025	800,000
2026	250,000
2027	300,000
2028	0
Thereafter	6,243,975
Total	$ 8,468,975

Long-Term Debt and Liquidity _5

Long-Term Debt and Liquidity Matters - Fair Value of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Estimated fair value of long-term debt, including current maturities
Carrying Amount	$ 8,415,622	$ 7,791,971
Fair Value	7,555,653	6,585,701
Arizona Public Service Company
Estimated fair value of long-term debt, including current maturities
Carrying Amount	7,291,891	6,793,529
Fair Value	6,459,718	5,629,491
Bright Canyon Energy Corporation
Estimated fair value of long-term debt, including current maturities
Carrying Amount	0	50,550
Fair Value	0	50,685
Pinnacle West
Estimated fair value of long-term debt, including current maturities
Carrying Amount	1,123,731	947,892
Fair Value	$ 1,095,935	$ 905,525

Long-Term Debt and Liquidity _6

Long-Term Debt and Liquidity Matters - Additional Information (Details) $ in Millions				12 Months Ended
	Jun. 30, 2023 USD ($)	Jan. 06, 2023 USD ($)	Feb. 11, 2022 USD ($) MW	Dec. 31, 2023 USD ($)	Oct. 27, 2023 USD ($)	Dec. 16, 2022 USD ($)	Dec. 17, 2020 USD ($)	Dec. 16, 2020 USD ($)
Maximum
Debt Provisions
Ratio of consolidated debt to consolidated capitalization (as a percent)				65%
Arizona Public Service Company
Long-Term Debt and Liquidity Matters [Line Items]
Annual amount of approved equity infusions				$ 150
Increased in equity contributions					$ 500
Equity infusion from Pinnacle West		$ 150
Debt Provisions
Actual ratio of consolidated debt to total consolidated capitalization required to be maintained as per the debt covenant (as a percent)				52%
Arizona Public Service Company | ACC
Debt Provisions
Long term debt authorization							$ 8,000	$ 7,500
Bright Canyon Energy Corporation
Debt Provisions
Solar plant capacity (in mw) | MW			31
Battery storage capacity (in mwh) | MW			20
5.55% Unsecured Senior Notes Due Aug 2033 | Arizona Public Service Company
Long-Term Debt and Liquidity Matters [Line Items]
Interest rate (as a percent)	5.55%
Debt Provisions
Notes Issued	$ 500
Term Loan | Non-Recourse Construction Term Loan Facility | Bright Canyon Energy Corporation
Long-Term Debt and Liquidity Matters [Line Items]
Notes issued			$ 36
Pinnacle West
Debt Provisions
Actual ratio of consolidated debt to total consolidated capitalization required to be maintained as per the debt covenant (as a percent)				60%
Pinnacle West | Term Loan
Long-Term Debt and Liquidity Matters [Line Items]
Notes issued						$ 175

Retirement Plans and Other Po_3

Retirement Plans and Other Postretirement Benefits - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Ultimate healthcare cost trend rate (pre-65 participants)	4.75%	4.75%
Initial and ultimate healthcare cost trend rate (post-65 participants)	2%	2%
Funded percentage (more than)	100%	100%
Partnership funding commitments, contribution amount (up to)	$ 50,000,000
Partnership funding commitments, funded amount	$ 38,000,000
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected long-term return on plan assets for next fiscal year (as a percent)	7%
Retiree medical cost reimbursement	$ 23,000,000	$ 26,000,000	$ 24,000,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected long-term return on plan assets for next fiscal year (as a percent)	6.90%
Employer contributions			100,000,000
Minimum contributions under MAP-21	$ 0
Pinnacle West
Defined Benefit Plan Disclosure [Line Items]
Expenses recorded for the defined contribution savings plan	$ 12,000,000	$ 12,000,000	$ 12,000,000
Arizona Public Service Company
Defined Benefit Plan Disclosure [Line Items]
APS's employees share of total cost of the plans (as a percent)	99%

Retirement Plans and Other Po_4

Retirement Plans and Other Postretirement Benefits - Net Periodic Benefit Costs and Portion including Portion Charged to Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net periodic benefit costs and the portion of these costs charged to expense
Portion of cost/(benefit) charged to expense	$ (40,648)	$ (98,487)	$ (112,541)
Pension Benefits
Net periodic benefit costs and the portion of these costs charged to expense
Service cost-benefits earned during the period	39,461	55,473	61,236
Interest cost on benefit obligation	153,561	107,492	98,566
Expected return on plan assets	(182,938)	(185,775)	(202,628)
Prior service credit (a)	0	0	0
Net actuarial (gain)/loss	38,420	17,515	15,948
Net periodic benefit cost/(benefit)	48,504	(5,295)	(26,878)
Portion of cost/(benefit) charged to expense	27,029	(16,431)	(32,743)
Other Benefits
Net periodic benefit costs and the portion of these costs charged to expense
Service cost-benefits earned during the period	8,567	16,470	17,796
Interest cost on benefit obligation	22,509	17,491	16,513
Expected return on plan assets	(43,486)	(46,042)	(41,444)
Prior service credit (a)	(37,789)	(37,789)	(37,705)
Net actuarial (gain)/loss	(9,614)	(12,835)	(10,093)
Net periodic benefit cost/(benefit)	(59,813)	(62,705)	(54,933)
Portion of cost/(benefit) charged to expense	$ (43,408)	$ (45,042)	$ (38,657)

Retirement Plans and Other Po_5

Retirement Plans and Other Postretirement Benefits - Changes Benefit Obligations and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Change in Benefit Obligation
Benefit obligation at the beginning of the period	$ 2,809,529	$ 3,716,824
Service cost	39,461	55,473	$ 61,236
Interest cost	153,561	107,492	98,566
Benefit payments	(210,737)	(212,565)
Actuarial (gain) loss	116,249	(857,695)
Benefit obligation at the end of the period	2,908,063	2,809,529	3,716,824
Change in Plan Assets
Balance at the beginning of the period	2,829,485	3,812,041
Actual return/(loss) on plan assets	199,098	(787,874)
Benefit payments	(193,034)	(194,682)
Balance at the end of the period	2,835,549	2,829,485	3,812,041
Funded/(Underfunded) Status at the end of the period	(72,514)	19,956
Other Benefits
Change in Benefit Obligation
Benefit obligation at the beginning of the period	409,461	591,841
Service cost	8,567	16,470	17,796
Interest cost	22,509	17,491	16,513
Benefit payments	(30,784)	(30,913)
Actuarial (gain) loss	20,681	(185,428)
Benefit obligation at the end of the period	430,434	409,461	591,841
Change in Plan Assets
Balance at the beginning of the period	652,287	872,435
Actual return/(loss) on plan assets	67,317	(193,807)
Benefit payments	(23,110)	(26,341)
Balance at the end of the period	696,494	652,287	$ 872,435
Funded/(Underfunded) Status at the end of the period	$ 266,060	$ 242,826

Retirement Plans and Other Po_6

Retirement Plans and Other Postretirement Benefits - Projected Benefit Obligation for Pension Plans (Details) - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Projected benefit obligation and the accumulated benefit obligation for pension plans with an accumulated obligation in excess of plan assets
Accumulated benefit obligation	$ 123,701	$ 126,759
Fair value of plan assets	0	0
Projected benefit obligation	129,891	133,818
Fair value of plan assets	$ 0	$ 0

Retirement Plans and Other Po_7

Retirement Plans and Other Postretirement Benefits - Amounts Recognized on the Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Amounts recognized on the Consolidated Balance Sheets
Noncurrent asset	$ 323,438	$ 396,599
Pension Benefits
Amounts recognized on the Consolidated Balance Sheets
Noncurrent asset	57,378	153,773
Current liability	(17,190)	(17,531)
Noncurrent liability	(112,702)	(116,286)
Net amount recognized (funded status)	(72,514)	19,956
Other Benefits
Amounts recognized on the Consolidated Balance Sheets
Noncurrent asset	266,060	242,826
Current liability	0	0
Noncurrent liability	0	0
Net amount recognized (funded status)	$ 266,060	$ 242,826

Retirement Plans and Other Po_8

Retirement Plans and Other Postretirement Benefits - Impact to Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Details related to accumulated other comprehensive loss
Net actuarial loss (gain)	$ 743,003	$ 681,335
Prior service credit	0	0
APS’s portion recorded as a regulatory (asset) liability	(696,476)	(637,656)
Income tax expense (benefit)	(11,506)	(10,797)
Accumulated other comprehensive loss (gain)	35,021	32,882
Other Benefits
Details related to accumulated other comprehensive loss
Net actuarial loss (gain)	(188,630)	(195,095)
Prior service credit	(39,054)	(76,843)
APS’s portion recorded as a regulatory (asset) liability	226,726	270,604
Income tax expense (benefit)	691	784
Accumulated other comprehensive loss (gain)	$ (267)	$ (550)

Retirement Plans and Other Po_9

Retirement Plans and Other Postretirement Benefits - Weighted-Average Assumptions for Pensions and Other Benefits (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Weighted-average assumptions used to determine benefit obligations
Rate of compensation increase	4.52%	4.57%
Initial healthcare cost trend rate (pre-65 participants)	6.25%	6.50%
Ultimate healthcare cost trend rate (pre-65 participants)	4.75%	4.75%
Number of years to ultimate trend rate (pre-65 participants)	5 years	6 years
Initial and ultimate healthcare cost trend rate (post-65 participants)	2%	2%
Interest crediting rate – cash balance pension plans	4.54%	4.50%
Weighted-average assumptions used to determine net periodic benefit costs
Initial healthcare cost trend rate (pre-65 participants)	6.50%	6%	6.50%
Ultimate healthcare cost trend rate (pre-65 participants)	4.75%	4.75%	4.75%
Number of years to ultimate trend rate (pre-65 participants)	5 years	3 years	4 years
Initial and ultimate healthcare cost trend rate (post-65 participants)	2%	2%	2%
Interest crediting rate – cash balance pension plans	4.50%	4.50%	4.50%
Pension Benefits
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)	5.21%	5.56%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	5.56%	2.92%	2.53%
Rate of compensation increase	4.57%	4%	4%
Expected long-term return on plan assets (as a percent)	6.70%	5%	5.30%
Other Benefits
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)	5.23%	5.58%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	5.58%	2.98%	2.63%
Expected long-term return on plan assets (as a percent)	6.80%	5.35%	4.90%

Retirement Plans and Other P_10

Retirement Plans and Other Postretirement Benefits - Asset Allocation (Details)	Dec. 31, 2023
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	100%
Actual Allocation	100%
Pension Benefits | Long-term fixed income assets
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	80%
Actual Allocation	78%
Pension Benefits | Return-seeking assets
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	20%
Actual Allocation	22%
Target Allocation	20%
Pension Benefits | Equities in US and other developed markets
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	12%
Pension Benefits | Equities in emerging markets
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	4%
Pension Benefits | Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	4%
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation	100%
Other Benefits | Long-term fixed income assets
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation	62%
Other Benefits | Return-seeking assets
Defined Benefit Plan Disclosure [Line Items]
Actual Allocation	38%

Retirement Plans and Other P_11

Retirement Plans and Other Postretirement Benefits - Fair Value of Pinnacle West's Pension Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	$ 399,298	$ 429,391
Fair value of plan assets	2,835,549	2,829,485	$ 3,812,041
Pension Benefits | 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	885,721	893,285
Pension Benefits | 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	1,550,530	1,506,809
Other Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	107,201	106,356
Fair value of plan assets	696,494	652,287	$ 872,435
Other Benefits | 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	391,019	371,731
Other Benefits | 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	198,274	174,200
Cash and cash equivalents | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other		0
Fair value of plan assets		1,252
Cash and cash equivalents | Pension Benefits | 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		1,252
Cash and cash equivalents | Pension Benefits | 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
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other		0
Fair value of plan assets		204
Cash and cash equivalents | Other Benefits | 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
Cash and cash equivalents | Other Benefits | 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 Benefits
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	1,415,346	1,374,810
Corporate | Pension Benefits | 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 Benefits | 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	1,415,346	1,374,810
Corporate | Other Benefits
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	189,902	166,879
Corporate | Other Benefits | 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 | 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	189,902	166,879
U.S. Treasury | Pension Benefits
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	622,273	635,245
U.S. Treasury | Pension Benefits | 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	622,273	635,245
U.S. Treasury | Pension Benefits | 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
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	207,665	221,936
U.S. Treasury | Other Benefits | 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	207,665	221,936
U.S. Treasury | Other Benefits | 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 fixed income | Pension Benefits
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	135,184	131,999
Other fixed income | Pension Benefits | 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 fixed income | Pension Benefits | 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	135,184	131,999
Other fixed income | Other Benefits
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	8,372	7,321
Other fixed income | Other Benefits | 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 fixed income | Other Benefits | 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	8,372	7,321
Common stock equities | Pension Benefits
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	150,657	155,231
Common stock equities | Pension Benefits | 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	150,657	155,231
Common stock equities | Pension Benefits | 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
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	139,952	127,493
Common stock equities | Other Benefits | 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	139,952	127,493
Common stock equities | Other Benefits | 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 Benefits
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	112,791	101,557
Mutual funds | Pension Benefits | 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	112,791	101,557
Mutual funds | Pension Benefits | 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
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	22,256	18,824
Mutual funds | Other Benefits | 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	22,256	18,824
Mutual funds | Other Benefits | 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 Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	192,945	181,912
Fair value of plan assets	192,945	181,912
Equities | Pension Benefits | 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 Benefits | 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
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	81,724	73,956
Fair value of plan assets	81,724	73,956
Equities | Other Benefits | 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 | 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 Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	140,613	174,228
Fair value of plan assets	140,613	174,228
Real estate | Pension Benefits | 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 Benefits | 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
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	20,001	23,541
Fair value of plan assets	20,001	23,541
Real estate | Other Benefits | 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 | 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
Partnerships | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other		13,359
Fair value of plan assets		13,359
Partnerships | Pension Benefits | 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
Partnerships | Pension Benefits | 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
Short-term investments and other | Pension Benefits
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	65,740	59,892
Fair value of plan assets	65,740	59,892
Short-term investments and other | Pension Benefits | 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 Benefits | 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
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Other	5,476	8,859
Fair value of plan assets	26,622	12,133
Short-term investments and other | Other Benefits | 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	21,146	3,274
Short-term investments and other | Other Benefits | 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

Retirement Plans and Other P_12

Retirement Plans and Other Postretirement Benefits - Estimated Future Benefit Payments (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Pension Benefits
Estimated Future Benefit Payments
2024	$ 244,772
2025	226,748
2026	229,322
2027	226,906
2028	229,397
Years 2029-2033	1,136,944
Other Benefits
Estimated Future Benefit Payments
2024	31,024
2025	30,446
2026	30,396
2027	30,024
2028	29,741
Years 2029-2033	$ 149,312

Leases - Additional information

Leases - Additional information (Details) $ in Billions	Dec. 31, 2023 USD ($) lease	Jan. 31, 2023 agreement
Leases [Abstract]
Number of lease agreements, sell and lease back | lease	3
Number of purchase power operating lease agreements | agreement		2
Lease not yet commenced | $	$ 7.1

Leases - Lease costs (Details)

Leases - Lease costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Leased Assets [Line Items]
Operating Lease Cost	$ 145,890	$ 122,062	$ 124,260
Variable lease cost	135,007	122,040	118,969
Short-term Lease Cost	21,530	9,928	3,872
Purchased Power & Energy Storage Lease Contracts
Operating Leased Assets [Line Items]
Operating Lease Cost	126,655	104,001	105,762
Land, Property & Equipment Leases
Operating Leased Assets [Line Items]
Operating Lease Cost	19,235	18,061	18,498
Total Lease Cost	$ 302,427	$ 254,030	$ 247,101

Leases - Maturity of our operat

Leases - Maturity of our operating lease liabilities (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Lessee, Lease, Description [Line Items]
2024	$ 122,951
2025	137,116
2026	148,518
2027	172,344
2028	173,811
Thereafter	899,903
Total lease commitments	1,654,643
Less imputed interest	376,571
Total lease liabilities	1,278,072
Purchased Power & Energy Storage Lease Contracts
Lessee, Lease, Description [Line Items]
2024	108,201
2025	124,968
2026	138,692
2027	164,613
2028	168,410
Thereafter	835,813
Total lease commitments	1,540,697
Less imputed interest	334,693
Total lease liabilities	1,206,004
Land, Property & Equipment Leases
Lessee, Lease, Description [Line Items]
2024	14,750
2025	12,148
2026	9,826
2027	7,731
2028	5,401
Thereafter	64,090
Total lease commitments	113,946
Less imputed interest	41,878
Total lease liabilities	$ 72,068

Leases - Other additional infor

Leases - Other additional information related to operating lease liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 31, 2023 agreement
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities — operating cash flows:	$ 123,472	$ 118,463	$ 116,661
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	$ 602,301	$ 16,990	$ 500,582
Weighted average remaining lease term	10 years	7 years
Weighted average discount rate	4.53%	2.21%
Number of purchase power operating lease agreements | agreement				2

Jointly-Owned Facilities (Detai

Jointly-Owned Facilities (Details) - Arizona Public Service Company $ in Thousands	Dec. 31, 2023 USD ($)
Palo Verde Units 1 and 3
Interests in jointly-owned facilities
Percent Owned	29.10%
Plant in Service	$ 1,990,237
Accumulated Depreciation	1,087,614
Construction Work in Progress	$ 21,442
Palo Verde Unit 2
Interests in jointly-owned facilities
Percent Owned	16.80%
Plant in Service	$ 681,483
Accumulated Depreciation	387,485
Construction Work in Progress	$ 12,700
Palo Verde Common
Interests in jointly-owned facilities
Percent Owned	28%
Plant in Service	$ 857,807
Accumulated Depreciation	356,962
Construction Work in Progress	65,911
Palo Verde Sale Leaseback
Interests in jointly-owned facilities
Plant in Service	351,050
Accumulated Depreciation	264,624
Construction Work in Progress	$ 0
Four Corners Generating Station
Interests in jointly-owned facilities
Percent Owned	63%
Plant in Service	$ 1,748,436
Accumulated Depreciation	659,780
Construction Work in Progress	$ 29,586
Cholla Common Facilities
Interests in jointly-owned facilities
Percent Owned	50.50%
Plant in Service	$ 250,994
Accumulated Depreciation	167,357
Construction Work in Progress	$ 7,487
ANPP 500kV System
Interests in jointly-owned facilities
Percent Owned	33.40%
Plant in Service	$ 136,145
Accumulated Depreciation	58,252
Construction Work in Progress	$ 4,801
Navajo Southern System
Interests in jointly-owned facilities
Percent Owned	25.20%
Plant in Service	$ 87,185
Accumulated Depreciation	36,743
Construction Work in Progress	$ 550
Palo Verde — Yuma 500kV System
Interests in jointly-owned facilities
Percent Owned	25.30%
Plant in Service	$ 24,057
Accumulated Depreciation	7,912
Construction Work in Progress	$ 432
Four Corners Switchyards
Interests in jointly-owned facilities
Percent Owned	57.50%
Plant in Service	$ 84,279
Accumulated Depreciation	21,918
Construction Work in Progress	$ 161
Phoenix — Mead System
Interests in jointly-owned facilities
Percent Owned	17.10%
Plant in Service	$ 39,772
Accumulated Depreciation	20,679
Construction Work in Progress	$ 257
Palo Verde — Rudd 500kV System
Interests in jointly-owned facilities
Percent Owned	50%
Plant in Service	$ 95,736
Accumulated Depreciation	32,665
Construction Work in Progress	$ 731
Morgan — Pinnacle Peak System
Interests in jointly-owned facilities
Percent Owned	63.20%
Plant in Service	$ 117,080
Accumulated Depreciation	26,990
Construction Work in Progress	$ 229
Round Valley System
Interests in jointly-owned facilities
Percent Owned	50%
Plant in Service	$ 548
Accumulated Depreciation	205
Construction Work in Progress	$ 0
Palo Verde — Morgan System
Interests in jointly-owned facilities
Percent Owned	87.50%
Plant in Service	$ 268,629
Accumulated Depreciation	40,962
Construction Work in Progress	$ 8,053
Hassayampa — North Gila System
Interests in jointly-owned facilities
Percent Owned	80%
Plant in Service	$ 151,684
Accumulated Depreciation	24,618
Construction Work in Progress	$ 0
Cholla 500kV Switchyard
Interests in jointly-owned facilities
Percent Owned	85.70%
Plant in Service	$ 8,445
Accumulated Depreciation	2,760
Construction Work in Progress	$ 0
Saguaro 500kV Switchyard
Interests in jointly-owned facilities
Percent Owned	60%
Plant in Service	$ 21,627
Accumulated Depreciation	14,060
Construction Work in Progress	$ 17
Kyrene — Knox System
Interests in jointly-owned facilities
Percent Owned	50%
Plant in Service	$ 578
Accumulated Depreciation	340
Construction Work in Progress	$ 0
Agua Fria Switchyard
Interests in jointly-owned facilities
Percent Owned	10%
Plant in Service	$ 0
Accumulated Depreciation	0
Construction Work in Progress	$ 77

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Thousands									1 Months Ended	12 Months Ended		132 Months Ended
	Jan. 01, 2024 USD ($) trust	Oct. 31, 2023 claim	Jan. 17, 2023 USD ($)	Sep. 30, 2022 USD ($)	Nov. 02, 2021 USD ($)	Jul. 03, 2018 USD ($)	Jul. 06, 2016	Aug. 14, 2014 USD ($)	Feb. 29, 2024 USD ($)	Dec. 31, 2023 USD ($) trust MW	Dec. 31, 2022 USD ($)	Jun. 30, 2022 timePeriod claim	Apr. 18, 2023 USD ($)
Schedule of Commitments and Contingencies [Line Items]
Coal mine reclamation										$ 184,007	$ 179,255
Non-recourse construction financing agreement													$ 140,000
Financing agreement of sponsor equity													$ 40,000
Production tax credit guarantees										$ 31,000
Kūpono Solar
Schedule of Commitments and Contingencies [Line Items]
Project plant capacity (in MW's) | MW										42
Asset purchase power agreement										20 years
Arizona Public Service Company
Schedule of Commitments and Contingencies [Line Items]
Number of VIE lessor trusts | trust										3
Amount of "all risk" (including nuclear hazards) insurance for property damage to, and decontamination of, property at Palo Verde										$ 2,800,000
Request second-year energy price for exported energy										22,400
Collateral assurance based on rating triggers										$ 62,600
Period to provide collateral assurance based on rating triggers										20 days
2024										$ 1,034,000
2025										1,190,000
2026										1,310,000
2027										1,284,000
2028										1,292,000
Thereafter										14,700,000
Coal mine reclamation										184,007	179,255
Arizona Public Service Company | Subsequent Event
Schedule of Commitments and Contingencies [Line Items]
Maximum insurance against public liability per occurrence for a nuclear incident	$ 16,300,000
Maximum available nuclear liability insurance	500,000
Remaining nuclear liability insurance through mandatory industry wide retrospective assessment program	15,800,000
Maximum assessment per reactor for each nuclear incident	165,900
Annual limit per incident with respect to maximum assessment	$ 24,700
Number of VIE lessor trusts | trust	3
Maximum potential retrospective assessment per incident of APS	$ 144,900
Annual payment limitation with respect to maximum potential retrospective assessment	$ 21,600
Arizona Public Service Company | Surety Bonds Expiring in 2025
Schedule of Commitments and Contingencies [Line Items]
Surety bonds expiring, amount										20,000
Arizona Public Service Company | Letter of Credit
Schedule of Commitments and Contingencies [Line Items]
Outstanding letters of credit										27,000
Arizona Public Service Company | SCE | Four Corners Units 4 and 5
Schedule of Commitments and Contingencies [Line Items]
Disallowance of plant investments					$ 194,000
Cost deferrals					$ 215,500
Arizona Public Service Company | Contaminated Groundwater Wells
Schedule of Commitments and Contingencies [Line Items]
Costs related to investigation and study under Superfund site										3,000
Remedial investigation work			$ 1,700
Arizona Public Service Company | Contaminated Groundwater Wells | Pending Litigation
Schedule of Commitments and Contingencies [Line Items]
Settlement amount				$ 20,700
Arizona Public Service Company | Renewable Energy Credits
Schedule of Commitments and Contingencies [Line Items]
2024										29,000
2025										27,000
2026										24,000
2027										20,000
2028										17,000
Thereafter										52,000
Arizona Public Service Company | Coal Mine Reclamation Balance Sheet Obligations
Schedule of Commitments and Contingencies [Line Items]
Coal mine reclamation										184,000	179,000
Arizona Public Service Company | Coal Mine Reclamation Obligations
Schedule of Commitments and Contingencies [Line Items]
2024										19,000
2025										20,000
2026										21,000
2027										22,000
2028										23,000
Thereafter										2,000
4CA | Four Corners
Schedule of Commitments and Contingencies [Line Items]
Percentage share cost of control							7%
NTEC | Four Corners
Schedule of Commitments and Contingencies [Line Items]
Option to purchase, ownership interest (as a percent)						7%
Proceeds from operating and maintenance cost reimbursement						$ 70,000
Asset purchase agreement, option to purchase, ownership interest, percentage						7%
Bright Canyon Energy Corporation | Clear Creek Wind Farm
Schedule of Commitments and Contingencies [Line Items]
Equity method investments				$ 17,100							0
Impairment of equity method investments											$ 12,800
Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal
Schedule of Commitments and Contingencies [Line Items]
Settlement amount, awarded to company								$ 18,460		138,200
Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal | Subsequent Event
Schedule of Commitments and Contingencies [Line Items]
Settlement amount, awarded to company									$ 18,390
Arizona Public Service Company and Palo Verde Owners vs. United States Department of Energy - Spent Nuclear Fuel and Waste Disposal | Arizona Public Service Company
Schedule of Commitments and Contingencies [Line Items]
Gain contingency, new claims filed, number | claim		10										9
Gain contingency, number of settlement agreement time periods | timePeriod												9
Settlement amount, awarded to company								$ 5,400		$ 40,200

Commitments and Contingencies_2

Commitments and Contingencies - Estimated Coal Take-or-pay Commitments and Actual Amount Purchased (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
Total take-or-pay commitments	$ 184,007	$ 179,255
Arizona Public Service Company
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2024	1,034,000
2025	1,190,000
2026	1,310,000
2027	1,284,000
2028	1,292,000
Thereafter	14,700,000
Total take-or-pay commitments	184,007	179,255
Arizona Public Service Company | Coal Take-or-Pay Commitments
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2024	208,694
2025	229,111
2026	221,122
2027	200,256
2028	205,237
Thereafter	647,377
Total take-or-pay commitments	1,700,000
Present value of commitments	1,400,000
Total purchases	255,219	305,502	$ 219,958
Arizona Public Service Company | Renewable Energy Credits
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2024	29,000
2025	27,000
2026	24,000
2027	20,000
2028	17,000
Thereafter	52,000
Arizona Public Service Company | Coal Mine Reclamation Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
2024	19,000
2025	20,000
2026	21,000
2027	22,000
2028	23,000
Thereafter	2,000
Arizona Public Service Company | Coal Mine Reclamation Balance Sheet Obligations
Fuel and Purchased Power Commitments and Purchase Obligations [Abstract]
Total take-or-pay commitments	$ 184,000	$ 179,000

Asset Retirement Obligations -

Asset Retirement Obligations - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Schedule of Asset Retirement Obligations [Line Items]
Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation	$ 17,980,157	$ 16,854,354
Arizona Public Service Company
Schedule of Asset Retirement Obligations [Line Items]
Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation	17,979,860	$ 16,800,254
Cholla | Arizona Public Service Company
Schedule of Asset Retirement Obligations [Line Items]
Increase (decrease) in asset retirement obligation	71,000
Four Corners Coal-Fired Power Plant | Arizona Public Service Company
Schedule of Asset Retirement Obligations [Line Items]
Increase (decrease) in asset retirement obligation	(7,000)
Navajo Coal-Fired Power Plant | Arizona Public Service Company
Schedule of Asset Retirement Obligations [Line Items]
Increase (decrease) in asset retirement obligation	8,000
Palo Verde | Arizona Public Service Company
Schedule of Asset Retirement Obligations [Line Items]
Increase (decrease) in asset retirement obligation	63,000
Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation	59,000
Decrease in regulatory liability	$ 4,000

Asset Retirement Obligations _2

Asset Retirement Obligations - Roll-Forward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Change in asset retirement obligations
Asset retirement obligations at the beginning of year	$ 797,762	$ 767,382
Changes attributable to:
Accretion expense	44,269	41,240
Settlements	(14,039)	(10,860)
Estimated cash flow revisions	135,323	0
Newly incurred obligation	2,686	0
Asset retirement obligations at the end of year	$ 966,001	$ 797,762

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Derivative liability statement of financial position not disclosed flag	interest rate derivative instruments
ASSETS
Cash equivalents		$ 10
Commodity contracts, assets	$ 132,229
Commodity contracts assets, other	(21,163)
Nuclear decommissioning trust	1,073,410	1,201,246
Nuclear decommissioning trust, other	476,409	408,849
Other special use fund	347,231	362,781
Other special use funds, other	963	2,196
Total assets	1,552,870	1,570,845
Total assets, other	456,209	409,356
LIABILITIES
Derivative instruments, other	15,357
Derivative instruments, total	(42,446)
Total liabilities	(42,446)
Total liabilities, other	15,357
Commodity contracts
ASSETS
Commodity contracts, assets	132,098	6,808
Commodity contracts assets, other	(21,163)	(1,689)
LIABILITIES
Derivative instruments, other	15,357	4,823
Derivative instruments, total	(41,537)	(123,888)
Interest rate swaps
ASSETS
Commodity contracts, assets	131
Commodity contracts assets, other	0
LIABILITIES
Derivative instruments, other	0
Derivative instruments, total	(909)
Equity securities
ASSETS
Nuclear decommissioning trust	18,485	10,297
Nuclear decommissioning trust, other	3,827	(767)
Other special use fund	67,937	43,187
Other special use funds, other	963	2,196
U.S. commingled equity funds
ASSETS
Nuclear decommissioning trust	472,582	409,616
U.S. Treasury debt
ASSETS
Nuclear decommissioning trust	211,923	319,734
Other special use fund	275,267	319,594
Corporate debt
ASSETS
Nuclear decommissioning trust	149,226	188,317
Mortgage-backed securities
ASSETS
Nuclear decommissioning trust	147,938	208,306
Municipal bonds
ASSETS
Nuclear decommissioning trust	64,881	59,323
Other special use fund	4,027	0
Other fixed income
ASSETS
Nuclear decommissioning trust	8,375	5,653
Level 1
ASSETS
Cash equivalents		10
Commodity contracts, assets	0
Nuclear decommissioning trust	226,581	330,798
Other special use fund	342,241	360,585
Total assets	568,822	691,393
LIABILITIES
Derivative instruments	0
Total liabilities	0
Level 1 | Commodity contracts
ASSETS
Commodity contracts, assets	0	0
LIABILITIES
Derivative instruments	0	0
Level 1 | Interest rate swaps
ASSETS
Commodity contracts, assets	0
LIABILITIES
Derivative instruments	0
Level 1 | Equity securities
ASSETS
Nuclear decommissioning trust	14,658	11,064
Other special use fund	66,974	40,991
Level 1 | U.S. commingled equity funds
ASSETS
Nuclear decommissioning trust	0	0
Level 1 | U.S. Treasury debt
ASSETS
Nuclear decommissioning trust	211,923	319,734
Other special use fund	275,267	319,594
Level 1 | Corporate debt
ASSETS
Nuclear decommissioning trust	0	0
Level 1 | Mortgage-backed securities
ASSETS
Nuclear decommissioning trust	0	0
Level 1 | Municipal bonds
ASSETS
Nuclear decommissioning trust	0	0
Other special use fund	0	0
Level 1 | Other fixed income
ASSETS
Nuclear decommissioning trust	0	0
Level 2
ASSETS
Cash equivalents		0
Commodity contracts, assets	127,260
Nuclear decommissioning trust	370,420	461,599
Other special use fund	4,027	0
Total assets	501,707	463,480
LIABILITIES
Derivative instruments	(26,783)
Total liabilities	(26,783)
Level 2 | Commodity contracts
ASSETS
Commodity contracts, assets	127,129	1,881
LIABILITIES
Derivative instruments	(25,874)	(127,016)
Level 2 | Interest rate swaps
ASSETS
Commodity contracts, assets	131
LIABILITIES
Derivative instruments	(909)
Level 2 | Equity securities
ASSETS
Nuclear decommissioning trust	0	0
Other special use fund	0	0
Level 2 | U.S. commingled equity funds
ASSETS
Nuclear decommissioning trust	0	0
Level 2 | U.S. Treasury debt
ASSETS
Nuclear decommissioning trust	0	0
Other special use fund	0	0
Level 2 | Corporate debt
ASSETS
Nuclear decommissioning trust	149,226	188,317
Level 2 | Mortgage-backed securities
ASSETS
Nuclear decommissioning trust	147,938	208,306
Level 2 | Municipal bonds
ASSETS
Nuclear decommissioning trust	64,881	59,323
Other special use fund	4,027	0
Level 2 | Other fixed income
ASSETS
Nuclear decommissioning trust	8,375	5,653
Level 3
ASSETS
Cash equivalents		0
Commodity contracts, assets	26,132
Nuclear decommissioning trust	0	0
Other special use fund	0	0
Total assets	26,132	6,616
LIABILITIES
Derivative instruments	(31,020)
Total liabilities	(31,020)
Level 3 | Commodity contracts
ASSETS
Commodity contracts, assets	26,132	6,616
LIABILITIES
Derivative instruments	(31,020)	(1,695)
Level 3 | Interest rate swaps
ASSETS
Commodity contracts, assets	0
LIABILITIES
Derivative instruments	0
Level 3 | Equity securities
ASSETS
Nuclear decommissioning trust	0	0
Other special use fund	0	0
Level 3 | U.S. commingled equity funds
ASSETS
Nuclear decommissioning trust	0	0
Level 3 | U.S. Treasury debt
ASSETS
Nuclear decommissioning trust	0	0
Other special use fund	0	0
Level 3 | Corporate debt
ASSETS
Nuclear decommissioning trust	0	0
Level 3 | Mortgage-backed securities
ASSETS
Nuclear decommissioning trust	0	0
Level 3 | Municipal bonds
ASSETS
Nuclear decommissioning trust	0	0
Other special use fund	0	0
Level 3 | Other fixed income
ASSETS
Nuclear decommissioning trust	0	0
Fair Value Measured at Net Asset Value Per Share | U.S. commingled equity funds
ASSETS
Nuclear decommissioning trust	$ 472,582	$ 409,616

Fair Value Measurements - Signi

Fair Value Measurements - Significant Unobservable Inputs Used to Value Level 3 Instruments (Details 2) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / MWh $ / MMBTU	Dec. 31, 2022 USD ($) $ / MMBTU $ / MWh
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	$ 1,570,845	$ 1,552,870
Liabilities		42,446
Level 3
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	6,616	26,132
Liabilities		31,020
Level 3 | Forward Contracts | Commodity Contracts
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	6,616	26,132
Liabilities	$ 1,695	$ 31,020
Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Commodity Contracts | Weighted Average
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (in usd per MWh) | $ / MWh	158.08	163.92
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	0.03	(5.08)
Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Commodity Contracts | Minimum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (in usd per MWh) | $ / MWh	37.79	37.79
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	0	(11.81)
Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Commodity Contracts | Maximum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (in usd per MWh) | $ / MWh	259.04	310.69
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	0.08	0
Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Electricity: | Commodity Contracts
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	$ 6,587	$ 26,132
Liabilities	658	1,759
Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Natural Gas: | Commodity Contracts
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	29	0
Liabilities	$ 1,037	$ 29,261

Fair Value Measurements - Fair

Fair Value Measurements - Fair value for our risk management activities (Details) - Commodity Contracts - Level 3 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative balance at beginning of period	$ (4,888)	$ (2,738)
Deferred as a regulatory asset or liability	(70,214)	(374)
Settlements	69,706	(1,123)
Transfers into Level 3 from Level 2	(1,289)	(846)
Transfers from Level 3 into Level 2	11,606	193
Net derivative balance at end of period	4,921	(4,888)
Net unrealized gains included in earnings related to instruments still held at end of period	$ 0	$ 0

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 501,557	$ 483,602	$ 618,720
Weighted average common shares outstanding — basic (in shares)	113,442	113,196	112,910
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units (in shares)	362	220	282
Weighted average common shares outstanding — diluted (in shares)	113,804	113,416	113,192
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic (in dollars per share)	$ 4.42	$ 4.27	$ 5.48
Net Income attributable to common shareholders - diluted (in dollars per share)	$ 4.41	$ 4.26	$ 5.47

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) program shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) performance_criteria
Stock-Based Compensation
Compensation cost that has been charged against income	$ 17	$ 16	$ 18
Total income tax benefit recognized	3	2	3
Total unrecognized compensation cost related to nonvested share-based compensation arrangements granted	$ 31
Expected weighted-average period of recognition of unrecognized compensation cost	2 years
Total fair value of shares vested	$ 24	25	$ 22
Performance Share Awards
Performance period	3 years
Number of unrelated performance element criteria | program	3
Number of performance element criteria | performance_criteria			2
Restricted Stock Units
Stock-Based Compensation
Share-based liabilities paid	$ 6	3	$ 4
Cash flow effect, cash used to settle awards	$ 3	$ 3	$ 3
Restricted Stock Units, Stock Grants and Stock Units
Vesting period	4 years
Percentage of cash that the participant may elect as a dividend for the first option available under the plan			50%
Percentage of stock that the participant may elect as dividend under second option of plan			50%
Performance Shares | Minimum
Performance Share Awards
Exact number of shares issued as a percentage of the target award	0%		0%
Performance Shares | Maximum
Performance Share Awards
Exact number of shares issued as a percentage of the target award	200%		200%
Officers and Key Employees | Restricted Stock Units
Restricted Stock Units, Stock Grants and Stock Units
Percentage of fully transferable shares of stock that the participant may elect as a deferral for the first option available under the plan			100%
Percentage of fully transferable shares of stock in that participant may receive cash			100%
Non-Officer Board of Director Member | Restricted Stock Units
Restricted Stock Units, Stock Grants and Stock Units
Percentage of fully transferable shares of stock that the participant may elect as a deferral for the first option available under the plan			100%
Percentage of cash that the participant may elect as a dividend for the first option available under the plan			100%
Percentage of stock that the participant may elect as dividend under second option of plan			50%
Percentage of fully transferable shares of stock that the participant may elect as a dividend equivalent deferral for the first option available under the plan			50%
2012 Plan
Stock-Based Compensation
Common shares available for grant (in shares) | shares	4.3
Common shares available for issuance (in shares) | shares	3.5

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Restricted Stock, Stock Grants, Stock Units and Performance Shares (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restricted Stock Units, Stock Grants, and Stock Units
Stocks granted and the weighted average fair value
Units granted (in shares)	192,295	174,791	152,345
Weighted-average grant date fair value (in dollars per share)	$ 74.32	$ 69.66	$ 76.72
Number of granted awards to be settled in cash (in shares)	0	0	51,074
Performance Shares
Stocks granted and the weighted average fair value
Units granted (in shares)	202,562	208,736	161,840
Weighted-average grant date fair value (in dollars per share)	$ 79.61	$ 77.63	$ 82.42

Stock-Based Compensation - Stat

Stock-Based Compensation - Status of Nonvested Restricted Stock, Stock Grants, Stock Units and Performance Shares (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restricted Stock Units, Stock Grants, and Stock Units
Nonvested shares
Balance at the beginning of the period (in shares)	317,587
Granted (in shares)	192,295	174,791	152,345
Vested (in shares)	(119,077)
Forfeited (in shares)	(16,438)
Balance at the end of the period (in shares)	374,367	317,587
Weighted-Average Grant-Date Fair Value
Balance at the beginning of the period (in dollars per share)	$ 73.91
Granted (in dollars per share)	74.32	$ 69.66	$ 76.72
Vested (in dollars per share)	80.71
Forfeited (in dollars per share)	73.95
Balance at the end of the period (in dollars per share)	$ 73.29	$ 73.91
Vested awards outstanding at end of year (in shares)	70,766
Vested awards outstanding at end of year (in dollars per share)
Number of nonvested awards to be settled in cash (in shares)	34,367
Performance Shares
Nonvested shares
Balance at the beginning of the period (in shares)	330,694
Granted (in shares)	202,562	208,736	161,840
Vested (in shares)	(169,290)
Forfeited (in shares)	(16,683)
Balance at the end of the period (in shares)	347,283	330,694
Weighted-Average Grant-Date Fair Value
Balance at the beginning of the period (in dollars per share)	$ 78.91
Granted (in dollars per share)	79.61	$ 77.63	$ 82.42
Vested (in dollars per share)	83.12
Forfeited (in dollars per share)	78.40
Balance at the end of the period (in dollars per share)	$ 77.29	$ 78.91
Vested awards outstanding at end of year (in shares)	155,708
Vested awards outstanding at end of year (in dollars per share)

Derivative Accounting - Additio

Derivative Accounting - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Oct. 18, 2022
Commodity Contracts
Derivative [Line Items]
Derivative asset	$ 6,808	$ 132,098
Additional collateral to counterparties for energy related non-derivative instrument contracts	$ 205,000
Interest rate swaps
Derivative [Line Items]
Derivative asset			$ 200
Arizona Public Service Company
Derivative [Line Items]
Percentage of unrealized gains and losses on certain derivatives deferred for future rate treatment before accounting treatment change	100%

Derivative Accounting - Outstan

Derivative Accounting - Outstanding Gross Notional Amounts Outstanding (Details) - Commodity Contracts MWh in Thousands	12 Months Ended
	Dec. 31, 2023 MWh Bcf	Dec. 31, 2022 MWh Bcf
Outstanding gross notional amount of derivatives
Power | MWh	1,212	1,197
Gas | Bcf	200	149

Derivative Accounting - Gains a

Derivative Accounting - Gains and Losses from Derivative Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Commodity Contracts | Fuel and purchased power | Not Designated as Hedging Instruments
Derivative Instruments Not Designated as Cash Flows Hedges
Net Gain (Loss) Recognized in Income	$ (370,145)	$ 307,287	$ 216,847

Derivative Accounting - Derivat

Derivative Accounting - Derivative Instruments in the Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets
Gross Recognized Derivatives		$ 132,229
Liabilities
Amounts  Reported on  Balance Sheets		(42,446)
Commodity Contracts
Assets
Gross Recognized Derivatives	$ 8,497	153,261
Amounts Offset	(1,694)	(21,191)
Net Recognized Derivatives	6,803	132,070
Other	5	28
Amounts  Reported on  Balance Sheets	6,808	132,098
Liabilities
Gross Recognized Derivatives	(128,711)	(56,893)
Amounts Offset	10,894	21,191
Net Recognized Derivatives	(117,817)	(35,702)
Other	(6,071)	(5,835)
Amounts  Reported on  Balance Sheets	(123,888)	(41,537)
Assets and Liabilities
Gross Recognized Derivatives	(120,214)	96,368
Amounts Offset	9,200	0
Net Recognized Derivatives	(111,014)	96,368
Other	(6,066)	(5,807)
Amounts  Reported on  Balance Sheets	(117,080)	90,561
Cash collateral provided or received subject to offsetting	9,200	0
Cash collateral received from counterparties	6,071	5,835
Cash margin provided to counterparties	5	28
Commodity Contracts | Current assets
Assets
Gross Recognized Derivatives	8,497	103,484
Amounts Offset	(1,694)	(15,808)
Net Recognized Derivatives	6,803	87,676
Other	5	28
Amounts  Reported on  Balance Sheets	6,808	87,704
Assets and Liabilities
Cash margin provided to counterparties	5	28
Commodity Contracts | Other Investments
Assets
Gross Recognized Derivatives	0	49,777
Amounts Offset	0	(5,383)
Net Recognized Derivatives	0	44,394
Other	0	0
Amounts  Reported on  Balance Sheets	0	44,394
Assets and Liabilities
Cash margin provided to counterparties	0	0
Commodity Contracts | Current liabilities
Liabilities
Gross Recognized Derivatives	(85,736)	(47,670)
Amounts Offset	10,894	15,808
Net Recognized Derivatives	(74,842)	(31,862)
Other	(6,071)	(5,835)
Amounts  Reported on  Balance Sheets	(80,913)	(37,697)
Assets and Liabilities
Cash collateral received from counterparties	6,071	5,835
Commodity Contracts | Deferred credits and other
Liabilities
Gross Recognized Derivatives	(42,975)	(9,223)
Amounts Offset	0	5,383
Net Recognized Derivatives	(42,975)	(3,840)
Other	0	0
Amounts  Reported on  Balance Sheets	(42,975)	(3,840)
Assets and Liabilities
Cash collateral received from counterparties	$ 0	$ 0

Derivative Accounting - Credit

Derivative Accounting - Credit Risk and Related Contingent Features (Details) - Commodity Contracts $ in Thousands	Dec. 31, 2023 USD ($)
Credit Risk and Credit-Related Contingent Features
Aggregate fair value of derivative instruments in a net liability position	$ 128,711
Cash collateral posted	9,200
Additional cash collateral in the event credit-risk related contingent features were fully triggered	$ 117,566

Other Income and Other Expens_2

Other Income and Other Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other income:
Interest income	$ 27,242	$ 7,326	$ 6,726
Gain on Sale of BCE (Note 20)	6,205	0	0
Miscellaneous	219	590	53
Total other income	33,666	7,916	45,100
Other expense:
Non-operating costs	(15,260)	(18,619)	(13,008)
Investment gains (losses) — net	(3,402)	(20,537)	(1,367)
Miscellaneous	(6,394)	(13,229)	(11,021)
Total other expense	(25,056)	(52,385)	(25,396)
Arizona Public Service Company
Other income:
Interest income	26,853	5,332	4,692
Miscellaneous	219	556	40
Total other income	27,072	5,888	43,053
Other expense:
Non-operating costs	(14,070)	(15,579)	(10,080)
Miscellaneous	(4,194)	(10,529)	(8,817)
Total other expense	(18,264)	(26,108)	(18,897)
ACC | Navajo Nation, Electrification Projects | Coal Community Transition Plan
Other expense:
Amount funded by shareholders		7,000
SCR deferral
Other income:
Debt return			14,955
SCR deferral | Arizona Public Service Company
Other income:
Debt return	0	0	14,955
Octotillo modernization project
Other income:
Debt return			23,366
Octotillo modernization project | Arizona Public Service Company
Other income:
Debt return	$ 0	$ 0	$ 23,366

Palo Verde Sale Leaseback Var_3

Palo Verde Sale Leaseback Variable Interest Entities - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) lease trust	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 1986 Trust
Palo Verde Sale Leaseback Variable Interest Entities
Net income attributable to noncontrolling interest	$ 17,224	$ 17,224	$ 17,224
Arizona Public Service Company
Palo Verde Sale Leaseback Variable Interest Entities
Number of VIE lessor trusts | trust	3
Net income attributable to noncontrolling interest	$ 17,224	17,224	17,224
Arizona Public Service Company | Variable Interest Entity
Palo Verde Sale Leaseback Variable Interest Entities
Number of VIE lessor trusts | Trust				3
Net income attributable to noncontrolling interest	17,000	$ 17,000	$ 17,000
Initial loss exposure to the VIEs noncontrolling equity participants during lease extension period	334,000
Arizona Public Service Company | Variable Interest Entity | Maximum
Palo Verde Sale Leaseback Variable Interest Entities
Maximum loss exposure to the VIE's noncontrolling equity participants during lease extension period (up to)	$ 501,000
Arizona Public Service Company | Period 2022 through 2023 | Variable Interest Entity
Palo Verde Sale Leaseback Variable Interest Entities
Number of leases under which assets are retained | lease	3
Annual lease payments	$ 21,000
Arizona Public Service Company | Period 2022 through 2023 | Variable Interest Entity | Maximum
Palo Verde Sale Leaseback Variable Interest Entities
Lease period (up to)	2 years

Palo Verde Sale Leaseback Var_4

Palo Verde Sale Leaseback Variable Interest Entities - Schedule of VIEs (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Palo Verde Sale Leaseback Variable Interest Entities
Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation	$ 17,980,157	$ 16,854,354
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Equity-Noncontrolling interests	107,198	111,229
Arizona Public Service Company
Palo Verde Sale Leaseback Variable Interest Entities
Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation	17,979,860	16,800,254
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Equity-Noncontrolling interests	107,198	111,229
Palo Verde VIE | Arizona Public Service Company
Palo Verde Sale Leaseback Variable Interest Entities
Palo Verde sale leaseback property, plant and equipment, net of accumulated depreciation	86,426	90,296
Amounts relating to the VIEs included in Condensed Consolidated Balance Sheets
Equity-Noncontrolling interests	$ 107,198	$ 111,229

Investments in Nuclear Decomm_3

Investments in Nuclear Decommissioning Trusts and Other Special Use Funds - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Arizona Public Service Company
Schedule of Equity Method Investments [Line Items]
Employee medical claims amount	$ 14	$ 15

Investments in Nuclear Decomm_4

Investments in Nuclear Decommissioning Trusts and Other Special Use Funds (Details) - Arizona Public Service Company - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Nuclear decommissioning trust fund assets
Fair Value	$ 1,564,027	$ 1,420,641
Total Unrealized Gains	358,112	337,994
Total Unrealized Losses	(40,868)	(69,091)
Amortized cost	1,120,000	927,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	112,094	9,437	$ 134,659
Realized losses	(41,780)	(40,239)	(8,438)
Proceeds from the sale of securities	1,679,722	1,207,197	1,720,966
Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Fair Value	1,201,246	1,073,410
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	111,922	9,017	134,610
Realized losses	(41,212)	(40,239)	(8,431)
Proceeds from the sale of securities	1,324,978	979,639	1,457,305
Other Special Use Funds
Nuclear decommissioning trust fund assets
Fair Value	362,781	347,231
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	172	420	49
Realized losses	(568)	0	(7)
Proceeds from the sale of securities	354,744	227,558	$ 263,661
Equity securities
Nuclear decommissioning trust fund assets
Equity securities	461,671	554,214
Total Unrealized Gains	336,555	334,817
Total Unrealized Losses	0	(267)
Equity securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Equity securities	420,680	487,240
Equity securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Equity securities	40,991	66,974
Available for sale-fixed income securities
Nuclear decommissioning trust fund assets
Fair Value	1,100,927	861,637
Total Unrealized Gains	21,518	3,177
Total Unrealized Losses	(40,868)	(68,795)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	121,606
1 year – 5 years	424,772
5 years – 10 years	201,452
Greater than 10 years	353,097
Total	1,100,927
Available for sale-fixed income securities | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Fair Value	781,333	582,343
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	26,057
1 year – 5 years	225,891
5 years – 10 years	176,288
Greater than 10 years	353,097
Total	781,333
Available for sale-fixed income securities | Other Special Use Funds
Nuclear decommissioning trust fund assets
Fair Value	319,594	279,294
Available for sale-fixed income securities | Coal Reclamation Escrow Account
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	58,692
1 year – 5 years	46,120
5 years – 10 years	0
Greater than 10 years	0
Total	104,812
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	36,857
1 year – 5 years	152,761
5 years – 10 years	25,164
Greater than 10 years	0
Total	214,782
Other
Nuclear decommissioning trust fund assets
Fair Value	1,429	4,790
Total Unrealized Gains	39	0
Total Unrealized Losses	0	(29)
Other | Nuclear Decommissioning Trusts
Nuclear decommissioning trust fund assets
Fair Value	(767)	3,827
Other | Other Special Use Funds
Nuclear decommissioning trust fund assets
Fair Value	$ 2,196	$ 963

Changes in Accumulated Other _3

Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	$ 6,159,876	$ 6,021,460
Ending balance	6,284,862	6,159,876
Accumulated Other Comprehensive Loss
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(31,435)	(54,861)
OCI (loss) before reclassifications	(3,707)	19,423
Amounts reclassified from accumulated other comprehensive loss	1,998	4,003
Ending balance	(33,144)	(31,435)
Pension and Other Postretirement Benefits
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(32,332)	(53,885)
OCI (loss) before reclassifications	(4,420)	17,550
Amounts reclassified from accumulated other comprehensive loss	1,998	4,003
Ending balance	(34,754)	(32,332)
Derivative Instruments
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	897	(976)
OCI (loss) before reclassifications	713	1,873
Amounts reclassified from accumulated other comprehensive loss	0	0
Ending balance	1,610	897
Arizona Public Service Company
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	7,052,955	6,750,473
Ending balance	7,349,136	7,052,955
Arizona Public Service Company | Accumulated Other Comprehensive Loss
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(15,596)	(34,880)
OCI (loss) before reclassifications	(3,383)	15,646
Amounts reclassified from accumulated other comprehensive loss	1,760	3,638
Ending balance	(17,219)	(15,596)
Arizona Public Service Company | Pension and Other Postretirement Benefits
Changes in accumulated other comprehensive income (loss) by component
Beginning balance	(15,596)	(34,880)
OCI (loss) before reclassifications	(3,383)	15,646
Amounts reclassified from accumulated other comprehensive loss	1,760	3,638
Ending balance	$ (17,219)	$ (15,596)

Sale of Bright Canyon Energy (D

Sale of Bright Canyon Energy (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 31, 2024	Aug. 04, 2023	Feb. 11, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale relating to BCE	$ 6,423	$ 0	$ 0
Bridge Loan | Equity Bridge Loan Facility | Bright Canyon Energy Corporation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt instrument, face amount					$ 31,000	$ 31,000
Term Loan | Non-Recourse Construction Term Loan Facility | Bright Canyon Energy Corporation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt instrument, face amount						$ 36,000
Discontinued Operations, Disposed of by Sale | Bright Canyon Energy Corporation
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received					$ 44,000
Gain on sale relating to BCE	6,000
Assets held-for-sale	35,000
Discontinued Operations, Disposed of by Sale | Bright Canyou Energy Corportion | Ameresco, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Note receivable, net book value	$ 28,000
Discontinued Operations, Disposed of by Sale | Bright Canyou Energy Corportion | Subsequent Event
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Investment tax credits				$ 28,000

Schedule I - Condensed Financ_2

Schedule I - Condensed Financial Information of Registrant - Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CONDENSED FINANCIAL STATEMENTS
Operating expenses	$ 3,871,351	$ 3,592,474	$ 2,998,525
Other
Total	102,376	99,281	173,982
Interest expense	374,887	283,569	254,314
Income tax benefit	76,912	74,827	110,086
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	501,557	483,602	618,720
Other comprehensive income (loss) — attributable to common shareholders	(1,709)	23,426	7,935
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	499,848	507,028	626,655
Pinnacle West
CONDENSED FINANCIAL STATEMENTS
Operating expenses	11,249	8,850	10,245
Other
Equity in earnings of subsidiaries	539,962	500,042	628,916
Other income (expense)	2,823	(4,725)	(4,919)
Total	542,785	495,317	623,997
Interest expense	47,251	18,861	10,672
Income before income taxes	484,285	467,606	603,080
Income tax benefit	(17,272)	(15,996)	(15,640)
NET INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	501,557	483,602	618,720
Other comprehensive income (loss) — attributable to common shareholders	(1,709)	23,426	7,935
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON SHAREHOLDERS	$ 499,848	$ 507,028	$ 626,655

Schedule I - Condensed Financ_3

Schedule I - Condensed Financial Information of Registrant - Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 4,955	$ 4,832
Accounts receivable	513,892	453,209
Income tax receivable	332	14,086
Assets held for sale (Note 20)	35,139	0
Other current assets	101,417	60,091
Total current assets	1,926,967	1,750,554
Investments and other assets
Other assets	102,845	125,672
Total investments and other assets	1,666,872	1,590,707
TOTAL ASSETS	24,661,153	22,723,405
Current liabilities
Accounts payable	442,455	430,425
Accrued taxes	166,833	164,440
Common dividends payable	99,813	97,895
Outstanding short-term borrowings	609,500	340,720
Current maturities of long-term debt	875,000	50,685
Operating lease liabilities	67,883	105,210
Other current liabilities	193,524	148,276
Total current liabilities	2,889,347	1,762,141
Deferred credits and other
Long-term debt less current maturities	7,540,622	7,741,286
Operating lease liabilities	1,210,189	639,247
Other	251,469	247,400
Total deferred credits and other	7,946,322	7,060,102
COMMITMENTS AND CONTINGENCIES (Note 10)
Common stock equity
Common stock	2,752,676	2,724,740
Accumulated other comprehensive loss (Note 19)	(33,144)	(31,435)
Retained earnings	3,466,317	3,360,347
Total shareholders’ equity	6,177,664	6,048,647
Noncontrolling interests	107,198	111,229
Total equity	6,284,862	6,159,876	$ 6,021,460	$ 5,752,793
TOTAL LIABILITIES AND EQUITY	24,661,153	22,723,405
Pinnacle West
Current assets
Cash and cash equivalents	9	0
Accounts receivable	163,829	132,061
Income tax receivable	1,832	14,494
Assets held for sale (Note 20)	35,139	0
Other current assets	28,379	288
Total current assets	229,188	146,843
Investments and other assets
Investments in subsidiaries	7,369,159	7,105,789
Deferred income taxes	15,746	1,521
Other assets	22,839	23,153
Total investments and other assets	7,407,744	7,130,463
TOTAL ASSETS	7,636,932	7,277,306
Current liabilities
Accounts payable	8,176	6,499
Accrued taxes	4,543	7,694
Common dividends payable	99,813	97,895
Outstanding short-term borrowings	76,650	15,720
Current maturities of long-term debt	625,000	0
Operating lease liabilities	127	117
Other current liabilities	11,400	14,637
Total current liabilities	825,709	142,562
Deferred credits and other
Long-term debt less current maturities	498,731	947,892
Pension liabilities	6,487	8,218
Operating lease liabilities	1,332	1,459
Other	19,811	17,299
Total deferred credits and other	27,630	26,976
COMMITMENTS AND CONTINGENCIES (Note 10)
Common stock equity
Common stock	2,744,491	2,719,735
Accumulated other comprehensive loss (Note 19)	(33,144)	(31,435)
Retained earnings	3,466,317	3,360,347
Total shareholders’ equity	6,177,664	6,048,647
Noncontrolling interests	107,198	111,229
Total equity	6,284,862	6,159,876
TOTAL LIABILITIES AND EQUITY	$ 7,636,932	$ 7,277,306

Schedule I - Condensed Financ_4

Schedule I - Condensed Financial Information of Registrant - Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income	$ 518,781	$ 500,826	$ 635,944
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	854,136	817,814	719,141
Deferred income taxes	(24,310)	43,202	117,471
Accounts receivable	(61,983)	(63,869)	(72,559)
Accounts payable	(75,623)	90,076	20,267
Net cash provided by operating activities	1,207,697	1,241,441	860,014
Cash flows from investing activities
Proceeds from sale relating to BCE	23,400	0	0
Net cash used for investing activities	(1,694,249)	(1,618,046)	(1,386,929)
Cash flows from financing activities
Issuance of long-term debt	689,349	875,537	746,999
Short-term debt repayments under revolving credit facility	0	0	(19,000)
Short-term borrowings and (repayments) — net	241,900	48,720	142,000
Dividends paid on common stock	(386,486)	(378,881)	(369,478)
Repayment of long-term debt	(32,740)	(150,000)	0
Common stock equity issuance and purchases — net	(4,093)	(2,653)	(2,350)
Net cash provided by financing activities	486,675	371,468	476,916
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	123	(5,137)	(49,999)
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	4,832	9,969	59,968
CASH AND CASH EQUIVALENTS AT END OF YEAR	4,955	4,832	9,969
Pinnacle West
Cash flows from operating activities
Net income	501,557	483,602	618,720
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in earnings of subsidiaries — net	(539,962)	(500,042)	(628,916)
Gain on sale relating to BCE	(6,423)	0	0
Depreciation and amortization	76	76	93
Deferred income taxes	(13,955)	17,256	(11,381)
Accounts receivable	(28,273)	(8,535)	8,897
Accounts payable	1,839	3,431	(2,598)
Accrued taxes and income tax receivables — net	9,505	(25,157)	16,079
Dividends received from subsidiaries	393,600	385,800	376,500
Other	(14,201)	47,719	4,214
Net cash provided by operating activities	303,763	404,150	381,608
Cash flows from investing activities
Proceeds from sale relating to BCE	23,400	0	0
Investments in subsidiaries	(119,682)	(186,630)	(145,266)
Repayments of loans from subsidiaries and other	6,526	14,308	4,017
Advances of loans to subsidiaries	(59,349)	(3,308)	(12,256)
Net cash used for investing activities	(149,105)	(175,630)	(153,505)
Cash flows from financing activities
Issuance of long-term debt	175,000	300,000	300,000
Short-term debt repayments under revolving credit facility	0	0	(19,000)
Short-term borrowings and (repayments) — net	60,930	2,420	(136,700)
Dividends paid on common stock	(386,486)	(378,881)	(369,478)
Repayment of long-term debt	0	(150,000)	0
Common stock equity issuance and purchases — net	(4,093)	(2,653)	(2,350)
Net cash provided by financing activities	(154,649)	(229,114)	(227,528)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	9	(594)	575
CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR	0	594	19
CASH AND CASH EQUIVALENTS AT END OF YEAR	$ 9	$ 0	$ 594