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