CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
CURRENT ASSETS
Cash and cash equivalents	$ 564,712	$ 110,188
Customer and other receivables	365,868	324,207
Accrued unbilled revenues	184,169	103,292
Allowance for doubtful accounts	(4,126)	(7,981)
Materials and supplies (at average cost)	203,118	181,414
Fossil fuel (at average cost)	25,403	21,575
Deferred income taxes	107,732	124,897
Income tax receivable (Note 6)		2,483
Assets from risk management activities (Note 8)	27,713	73,788
Deferred fuel and purchased power regulatory asset (Note 3)	31,611
Other regulatory assets (Note 3)	55,852	62,286
Other current assets	29,183	28,362
Total current assets	1,591,235	1,024,511
INVESTMENTS AND OTHER ASSETS
Assets from risk management activities (Note 8)	32,316	39,032
Nuclear decommissioning trust (Note 17)	488,551	469,886
Other assets	63,731	116,216
Total investments and other assets	584,598	625,134
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	13,423,406	13,201,960
Accumulated depreciation and amortization	(4,684,760)	(4,514,204)
Net	8,738,646	8,687,756
Construction work in progress	618,728	459,361
Palo Verde sale leaseback, net of accumulated depreciation (Note 7)	133,832	137,956
Intangible assets, net of accumulated amortization	176,401	184,952
Nuclear fuel, net of accumulated amortization	134,232	108,794
Total property, plant and equipment	9,801,839	9,578,819
DEFERRED DEBITS
Regulatory assets (Note 3)	977,975	986,370
Income tax receivable (Note 6)	68,201	65,103
Other	126,515	113,061
Total deferred debits	1,172,691	1,164,534
TOTAL ASSETS	13,150,363	12,392,998
CURRENT LIABILITIES
Accounts payable	281,647	236,354
Accrued taxes (Note 6)	191,507	104,711
Accrued interest	56,174	54,831
Short-term borrowings		16,600
Current maturities of long-term debt	876,363	631,879
Customer deposits	71,772	68,322
Liabilities from risk management activities (Note 8)	60,667	58,976
Deferred fuel and purchased power regulatory liability (Note 3)		58,442
Other regulatory liabilities (Note 3)	94,374	80,526
Other current liabilities	150,764	139,063
Total current liabilities	1,783,268	1,449,704
LONG-TERM DEBT LESS CURRENT MATURITIES
Long-term debt less current maturities	2,963,457	2,948,991
Palo Verde sale leaseback lessor notes less current maturities (Note 7)	83,130	96,803
Total long-term debt less current maturities	3,046,587	3,045,794
DEFERRED CREDITS AND OTHER
Deferred income taxes	1,955,458	1,863,861
Regulatory liabilities (Note 3)	689,120	614,063
Liability for asset retirements (Note 15)	258,332	328,571
Liabilities for pension and other postretirement benefits (Note 4)	877,485	813,121
Liabilities from risk management activities (Note 8)	58,745	65,390
Customer advances	112,730	121,645
Coal mine reclamation	117,779	117,243
Unrecognized tax benefits (Note 6)	76,936	66,349
Other	170,928	132,031
Total deferred credits and other	4,317,513	4,122,274
COMMITMENTS AND CONTINGENCIES (SEE NOTES)
EQUITY (Note 9)
Common stock, no par value	2,441,621	2,421,372
Treasury stock	(5,232)	(2,239)
Total common stock	2,436,389	2,419,133
Retained earnings	1,579,240	1,423,961
Accumulated other comprehensive loss:
Pension and other postretirement benefits	(56,582)	(59,420)
Derivative instruments	(64,962)	(100,347)
Total accumulated other comprehensive loss	(121,544)	(159,767)
Total shareholders' equity	3,894,085	3,683,327
Noncontrolling interests (Note 7)	108,910	91,899
Total equity	4,002,995	3,775,226
TOTAL LIABILITIES AND EQUITY	$ 13,150,363	$ 12,392,998