CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
CURRENT ASSETS
Cash and cash equivalents	$ 9,634	$ 4,955
Customer and other receivables	425,716	513,892
Accrued unbilled revenues	166,479	167,553
Allowance for doubtful accounts (Note 2)	(19,224)	(22,433)
Materials and supplies (at average cost)	438,943	444,344
Income tax receivable	0	332
Fossil fuel (at average cost)	50,230	49,203
Assets from risk management activities (Note 7)	78	6,808
Assets held for sale (Note 14)	0	35,139
Deferred fuel and purchased power regulatory asset (Note 4)	387,737	463,195
Other regulatory assets (Note 4)	191,132	162,562
Other current assets	131,257	101,417
Total current assets	1,781,982	1,926,967
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trusts (Notes 11 and 12)	1,239,024	1,201,246
Other special use funds (Notes 11 and 12)	364,225	362,781
Other assets	106,830	102,845
Total investments and other assets	1,710,079	1,666,872
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	24,461,914	24,211,167
Accumulated depreciation and amortization	(8,594,795)	(8,408,040)
Net	15,867,119	15,803,127
Construction work in progress	1,685,365	1,724,004
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	85,459	86,426
Intangible assets, net of accumulated amortization	512,874	267,110
Nuclear fuel, net of accumulated amortization	113,825	99,490
Total property, plant and equipment	18,264,642	17,980,157
DEFERRED DEBITS
Regulatory assets (Note 4)	1,371,260	1,390,279
Operating lease right-of-use assets	1,325,138	1,309,975
Assets for pension and other postretirement benefits (Note 5)	334,765	323,438
Other	59,847	63,465
Total deferred debits	3,091,010	3,087,157
TOTAL ASSETS	24,847,713	24,661,153
CURRENT LIABILITIES
Accounts payable	476,629	442,455
Accrued taxes	224,851	166,833
Accrued interest	74,001	72,916
Common dividends payable	0	99,813
Short-term borrowings (Note 3)	793,500	609,500
Current maturities of long-term debt (Note 3)	875,000	875,000
Customer deposits	42,059	42,037
Liabilities from risk management activities (Note 7)	113,530	80,913
Liabilities for asset retirements	33,048	28,550
Operating lease liabilities	69,102	67,883
Regulatory liabilities (Note 4)	221,552	209,923
Other current liabilities	132,597	193,524
Total current liabilities	3,055,869	2,889,347
LONG-TERM DEBT LESS CURRENT MATURITIES (Note 3)	7,541,871	7,540,622
DEFERRED CREDITS AND OTHER
Deferred income taxes	2,396,743	2,416,480
Regulatory liabilities (Note 4)	1,966,120	1,965,865
Liabilities for asset retirements	946,457	937,451
Liabilities for pension benefits (Note 5)	110,597	112,702
Liabilities from risk management activities (Note 7)	34,872	42,975
Customer advances	533,180	533,580
Coal mine reclamation	185,229	184,007
Deferred investment tax credit	257,448	257,743
Unrecognized tax benefits	34,511	33,861
Operating lease liabilities	1,225,468	1,210,189
Other	248,815	251,469
Total deferred credits and other	7,939,440	7,946,322
COMMITMENTS AND CONTINGENCIES (Note 8)
EQUITY
Common stock, no par value; authorized 150,000,000 shares, 113,686,849 and 113,537,689 issued at respective dates	2,757,506	2,752,676
Treasury stock at cost; 128,234 and 113,272 shares at respective dates	(9,073)	(8,185)
Total common stock	2,748,433	2,744,491
Retained earnings	3,483,178	3,466,317
Accumulated other comprehensive loss (Note 13)	(32,582)	(33,144)
Total shareholder equity	6,199,029	6,177,664
Noncontrolling interests (Note 6)	111,504	107,198
Total equity	6,310,533	6,284,862
TOTAL LIABILITIES AND EQUITY	$ 24,847,713	$ 24,661,153