CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
CURRENT ASSETS
Cash and cash equivalents	$ 11,228	$ 33,583
Customer and other receivables	316,722	284,183
Accrued unbilled revenues	168,450	125,239
Allowance for doubtful accounts	(3,302)	(3,748)
Materials and supplies (at average cost)	217,222	204,387
Fossil fuel (at average cost)	30,177	22,000
Deferred income taxes	87,690	130,571
Income tax receivable (Note 6)	885	6,466
Assets from risk management activities (Note 8)	29,991	30,264
Deferred fuel and purchased power regulatory asset (Note 3)		27,549
Other regulatory assets (Note 3)	54,857	69,072
Other current assets	33,496	26,904
Total current assets	947,416	956,470
INVESTMENTS AND OTHER ASSETS
Assets from risk management activities (Note 8)	43,526	49,322
Nuclear decommissioning trust (Note 15)	544,933	513,733
Other assets	64,800	64,588
Total investments and other assets	653,259	627,643
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	14,048,957	13,753,971
Accumulated depreciation and amortization	(4,843,868)	(4,709,991)
Net	9,205,089	9,043,980
Construction work in progress	458,441	496,745
Palo Verde sale leaseback, net of accumulated depreciation (Note 7)	130,929	132,864
Intangible assets, net of accumulated amortization	163,727	170,571
Nuclear fuel, net of accumulated amortization	159,493	118,098
Total property, plant and equipment	10,117,679	9,962,258
DEFERRED DEBITS
Regulatory assets (Note 3)	1,283,322	1,352,079
Income tax receivable (Note 6)	69,508	68,633
Other	143,223	143,935
Total deferred debits	1,496,053	1,564,647
TOTAL ASSETS	13,214,407	13,111,018
CURRENT LIABILITIES
Accounts payable	316,329	326,987
Accrued taxes (Note 6)	133,766	120,289
Accrued interest	61,451	54,872
Common dividends payable	57,479
Short-term borrowings	109,000
Current maturities of long-term debt	57,962	477,435
Customer deposits	74,575	72,176
Liabilities from risk management activities (Note 8)	64,442	53,968
Deferred fuel and purchased power regulatory liability (Note 3)	325
Other regulatory liabilities (Note 3)	89,433	88,362
Other current liabilities	139,561	148,616
Total current liabilities	1,104,323	1,342,705
LONG-TERM DEBT LESS CURRENT MATURITIES
Long-term debt less current maturities	3,313,992	2,953,507
Palo Verde sale leaseback lessor notes less current maturities (Note 7)	57,420	65,547
Total long-term debt less current maturities	3,371,412	3,019,054
DEFERRED CREDITS AND OTHER
Deferred income taxes	1,946,540	1,925,388
Regulatory liabilities (Note 3)	738,693	737,332
Liability for asset retirements	289,641	279,643
Liabilities for pension and other postretirement benefits (Note 4)	1,243,256	1,268,910
Liabilities from risk management activities (Note 8)	108,554	82,495
Customer advances	111,655	116,805
Coal mine reclamation	118,374	117,896
Unrecognized tax benefits (Note 6)	72,977	72,270
Other	209,645	217,934
Total deferred credits and other	4,839,335	4,818,673
COMMITMENTS AND CONTINGENCIES (SEE NOTES)
EQUITY (Note 9)
Common stock, no par value	2,453,453	2,444,247
Treasury stock	(1,359)	(4,717)
Total common stock	2,452,094	2,439,530
Retained earnings	1,476,259	1,534,483
Accumulated other comprehensive loss:
Pension and other postretirement benefits	(63,675)	(65,447)
Derivative instruments	(86,643)	(86,716)
Total accumulated other comprehensive loss	(150,318)	(152,163)
Total shareholders' equity	3,778,035	3,821,850
Noncontrolling interests (Note 7)	121,302	108,736
Total equity	3,899,337	3,930,586
TOTAL LIABILITIES AND EQUITY	$ 13,214,407	$ 13,111,018