CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
CURRENT ASSETS
Cash and cash equivalents	$ 9,161	$ 9,526
Customer and other receivables	325,352	299,904
Accrued unbilled revenues	172,444	96,796
Allowance for doubtful accounts	(2,731)	(3,203)
Materials and supplies (at average cost)	230,310	221,682
Fossil fuel (at average cost)	38,835	38,028
Deferred income taxes	83,633	91,152
Income tax receivable (Note 5)		135,517
Assets from risk management activities (Note 7)	15,420	17,169
Deferred fuel and purchased power regulatory asset (Note 3)	1,043	20,755
Other regulatory assets (Note 3)	77,148	76,388
Other current assets	48,457	39,895
Total current assets	999,072	1,043,609
INVESTMENTS AND OTHER ASSETS
Assets from risk management activities (Note 7)	21,581	23,815
Nuclear decommissioning trust (Note 13)	682,359	642,007
Other assets	61,380	60,875
Total investments and other assets	765,320	726,697
PROPERTY, PLANT AND EQUIPMENT
Plant in service and held for future use	15,448,087	15,200,464
Accumulated depreciation and amortization	(5,388,667)	(5,300,219)
Net	10,059,420	9,900,245
Construction work in progress	584,152	581,369
Palo Verde sale leaseback, net of accumulated depreciation (Note 6)	123,190	125,125
Intangible assets, net of accumulated amortization	137,037	157,689
Nuclear fuel, net of accumulated amortization	125,246	124,557
Total property, plant and equipment	11,029,045	10,888,985
DEFERRED DEBITS
Regulatory assets (Note 3)	755,174	711,712
Other	141,706	137,683
Total deferred debits	896,880	849,395
TOTAL ASSETS	13,690,317	13,508,686
CURRENT LIABILITIES
Accounts payable	320,779	284,516
Accrued taxes (Note 5)	161,707	130,998
Accrued interest	52,740	48,351
Common dividends payable	62,656	62,528
Short-term borrowings (Note 2)	176,650	153,125
Current maturities of long-term debt (Note 2)	368,841	540,424
Customer deposits	74,779	76,101
Liabilities from risk management activities (Note 7)	21,502	31,892
Liabilities for asset retirements	35,726	32,896
Regulatory liabilities (Note 3)	114,204	99,273
Other current liabilities	165,123	158,540
Total current liabilities	1,554,707	1,618,644
LONG-TERM DEBT LESS CURRENT MATURITIES (Note 2)	2,999,513	2,796,465
DEFERRED CREDITS AND OTHER
Deferred income taxes	2,396,026	2,351,882
Regulatory liabilities (Note 3)	809,442	801,297
Liabilities for asset retirements (Note 16)	356,436	313,833
Liabilities for pension and other postretirement benefits (Note 4)	439,490	513,628
Liabilities from risk management activities (Note 7)	23,367	70,315
Customer advances	120,330	114,480
Coal mine reclamation	208,951	207,453
Deferred investment tax credit	181,236	152,361
Unrecognized tax benefits (Note 5)	22,814	42,209
Other	196,143	185,659
Total deferred credits and other	4,754,235	4,753,117
COMMITMENTS AND CONTINGENCIES (SEE NOTES)
EQUITY (Note 8)
Common stock, no par value; authorized 150,000,000 shares, 110,430,456 and 110,280,703 issued at respective dates	2,500,064	2,491,558
Treasury stock at cost; 23,824 and 98,944 shares at respective dates	(189)	(4,308)
Total common stock	2,499,875	2,487,250
Retained earnings	1,808,232	1,785,273
Accumulated other comprehensive loss:
Pension and other postretirement benefits	(55,848)	(54,995)
Derivative instruments	(18,369)	(23,058)
Total accumulated other comprehensive loss	(74,217)	(78,053)
Total shareholders' equity	4,233,890	4,194,470
Noncontrolling interests (Note 6)	147,972	145,990
Total equity	4,381,862	4,340,460
TOTAL LIABILITIES AND EQUITY	$ 13,690,317	$ 13,508,686