CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
CURRENT ASSETS
Cash and cash equivalents	$ 30,885	$ 3,838
Customer and other receivables	778,097	525,608
Accrued unbilled revenues (Note 4)	257,874	176,903
Allowance for doubtful accounts (Note 4)	(21,867)	(24,849)
Materials and supplies (at average cost)	519,178	469,022
Fossil fuel (at average cost)	19,515	32,420
Assets from risk management activities (Note 9)	6,636	10,578
Deferred fuel and purchased power regulatory asset (Note 6)	205,053	287,597
Other regulatory assets (Note 6)	130,572	133,372
Other current assets	74,712	74,915
Total current assets	2,000,655	1,689,404
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trusts (Notes 13 and 14)	1,393,446	1,282,845
Other special use funds (Notes 13 and 14)	429,932	408,357
Assets from risk management activities (Note 9)	15,600	5,980
Other assets	138,383	115,095
Total investments and other assets	1,977,361	1,812,277
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	26,268,660	25,860,950
Accumulated depreciation and amortization	(8,952,278)	(9,027,426)
Net	17,316,382	16,833,524
Construction work in progress	2,323,115	1,592,659
Palo Verde sale leaseback, net of accumulated depreciation (Note 8)	32,416	82,556
Intangible assets, net of accumulated amortization	544,356	591,310
Nuclear fuel, net of accumulated amortization	115,097	97,850
Total property, plant and equipment	20,331,366	19,197,899
DEFERRED DEBITS
Regulatory assets (Note 6)	1,471,310	1,389,489
Operating lease right-of-use assets (Note 16)	3,652,128	1,605,463
Assets for pension and other postretirement benefits (Note 7)	376,338	342,102
Other	83,747	66,126
Total deferred debits	5,583,523	3,403,180
TOTAL ASSETS	29,892,905	26,102,760
CURRENT LIABILITIES
Accounts payable	536,924	485,426
Accrued taxes	348,376	175,863
Accrued interest	99,233	81,799
Common dividends payable	0	106,592
Short-term borrowings (Note 5)	675,700	568,450
Current maturities of long-term debt (Note 5)	600,000	800,000
Customer deposits	61,716	44,345
Liabilities from risk management activities (Note 9)	39,078	52,340
Liabilities for asset retirements (Note 17)	59,800	50,009
Operating lease liabilities (Note 16)	203,740	100,367
Regulatory liabilities (Note 6)	194,094	206,955
Other current liabilities	146,818	171,651
Total current liabilities	2,965,479	2,843,797
LONG-TERM DEBT LESS CURRENT MATURITIES (Note 5)	9,204,259	8,058,648
DEFERRED CREDITS AND OTHER
Deferred income taxes	2,491,779	2,444,473
Regulatory liabilities (Note 6)	1,769,900	1,855,278
Liabilities for asset retirements (Note 17)	1,158,979	1,096,577
Liabilities for pension benefits (Note 7)	150,086	139,317
Liabilities from risk management activities (Note 9)	0	9,446
Customer advances	661,274	569,343
Coal mine reclamation	157,593	171,483
Deferred investment tax credit	239,470	249,490
Unrecognized tax benefits	87,245	44,233
Operating lease liabilities (Note 16)	3,562,895	1,520,877
Other	232,853	242,320
Total deferred credits and other	10,512,074	8,342,837
COMMITMENTS AND CONTINGENCIES (Note 10)
EQUITY
Common stock, no par value; 300,000,000 and 150,000,000 shares authorized at respective dates, 119,736,525 and 119,143,782 shares issued at respective dates	3,147,069	3,121,617
Treasury stock at cost; 46,968 and 46,968 shares at respective dates	(3,323)	(3,323)
Total common stock	3,143,746	3,118,294
Retained earnings	4,054,355	3,666,959
Accumulated other comprehensive loss (Note 15)	(30,091)	(30,942)
Total shareholder equity	7,168,010	6,754,311
Noncontrolling interests (Note 8)	43,083	103,167
Total equity	7,211,093	6,857,478
TOTAL LIABILITIES AND EQUITY	$ 29,892,905	$ 26,102,760