CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
CURRENT ASSETS
Cash and cash equivalents	$ 7,658	$ 4,832
Customer and other receivables	474,548	453,209
Accrued unbilled revenues	216,740	164,764
Allowance for doubtful accounts (Note 2)	(19,806)	(23,778)
Materials and supplies (at average cost)	442,735	410,481
Income tax receivable	4,240	14,086
Fossil fuel (at average cost)	50,057	40,155
Assets from risk management activities (Note 7)	12,105	87,835
Deferred fuel and purchased power regulatory asset (Note 4)	433,279	460,561
Other regulatory assets (Note 4)	128,600	78,318
Other current assets	101,581	60,091
Total current assets	1,851,737	1,750,554
INVESTMENTS AND OTHER ASSETS
Nuclear decommissioning trusts (Notes 11 and 12)	1,162,397	1,073,410
Other special use funds (Notes 11 and 12)	351,998	347,231
Assets from risk management activities (Note 7)	13,033	44,394
Other assets	127,318	125,672
Total investments and other assets	1,654,746	1,590,707
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	23,667,333	22,452,146
Accumulated depreciation and amortization	(8,198,608)	(7,929,878)
Net	15,468,725	14,522,268
Construction work in progress	1,495,494	1,882,791
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	88,361	90,296
Intangible assets, net of accumulated amortization	255,574	258,880
Nuclear fuel, net of accumulated amortization	100,019	100,119
Total property, plant and equipment	17,408,173	16,854,354
DEFERRED DEBITS
Regulatory assets (Note 4)	1,280,344	1,283,221
Operating lease right-of-use assets (Note 14)	1,337,355	801,688
Assets for pension and other postretirement benefits (Note 5)	396,615	396,599
Other	50,372	46,282
Total deferred debits	3,064,686	2,527,790
TOTAL ASSETS	23,979,342	22,723,405
CURRENT LIABILITIES
Accounts payable	436,808	430,425
Accrued taxes	163,797	164,440
Accrued interest	58,559	61,217
Common dividends payable	98,014	97,895
Short-term borrowings (Note 3)	305,350	340,720
Current maturities of long-term debt (Note 3)	318,907	50,685
Customer deposits	41,585	41,769
Liabilities from risk management activities (Note 7)	73,833	37,697
Liabilities for asset retirements (Note 15)	15,617	12,232
Operating lease liabilities (Note 14)	90,658	105,210
Regulatory liabilities (Note 4)	219,075	271,575
Other current liabilities	110,378	148,276
Total current liabilities	1,932,581	1,762,141
LONG-TERM DEBT LESS CURRENT MATURITIES (Note 3)	8,164,315	7,741,286
DEFERRED CREDITS AND OTHER
Deferred income taxes	2,357,517	2,384,421
Regulatory liabilities (Note 4)	2,032,525	2,061,776
Liabilities for asset retirements (Note 15)	823,502	785,530
Liabilities for pension benefits (Note 5)	112,537	116,286
Customer advances	536,579	422,103
Coal mine reclamation	181,636	179,255
Deferred investment tax credit	223,278	180,677
Unrecognized tax benefits	39,073	38,658
Operating lease liabilities (Note 14)	1,221,538	639,247
Other	278,124	252,149
Total deferred credits and other	7,806,309	7,060,102
COMMITMENTS AND CONTINGENCIES (Note 8)
EQUITY
Common stock, no par value; authorized 150,000,000 shares, 113,386,894 and 113,247,189 issued at respective dates	2,736,112	2,724,740
Treasury stock at cost; 75,767 and 73,613 shares at respective dates	(5,328)	(5,005)
Total common stock	2,730,784	2,719,735
Retained earnings	3,267,731	3,360,347
Accumulated other comprehensive loss (Note 13)	(31,591)	(31,435)
Total shareholders’ equity	5,966,924	6,048,647
Noncontrolling interests (Note 6)	109,213	111,229
Total equity	6,076,137	6,159,876
TOTAL LIABILITIES AND EQUITY	$ 23,979,342	$ 22,723,405