CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Plant and property, at original cost:
Electric	$ 2,194,959	$ 2,176,188
Natural gas	71,234	69,851
Other	38,748	37,983
Construction work in progress	99,755	56,347
Total plant and property, Gross	2,404,696	2,340,369
Accumulated depreciation and amortization	704,536	682,737
Total plant and property, Net	1,700,160	1,657,632
Current assets:
Cash and cash equivalents	10,850	3,375
Restricted cash	1,773	4,357
Accounts receivable - trade, net of allowance $1,889 and $945, respectively	46,035	38,874
Accrued unbilled revenues	20,968	23,254
Accounts receivable - other	19,652	13,277
Fuel, materials and supplies	51,564	61,870
Prepaid expenses and other	21,872	21,806
Unrealized gain in fair value of derivative contracts	53	96
Regulatory assets	6,478	6,377
Total current assets	179,245	173,286
Noncurrent assets and deferred charges:
Regulatory assets	234,496	243,958
Goodwill	39,492	39,492
Unamortized debt issuance costs	9,019	7,606
Unrealized gain in fair value of derivative contracts	127	191
Other	6,098	4,204
Total noncurrent assets and deferred charges	289,232	295,451
Total Assets	2,168,637	2,126,369
Capitalization and Liabilities
Common stock, $1 par value, 42,830,673 and 42,484,363 shares issued and outstanding, respectively	42,831	42,484
Capital in excess of par value	634,457	628,199
Retained earnings	50,070	47,115
Total common stockholders' equity	727,358	717,798
Long-term debt (net of current portion):
Obligations under capital lease	4,306	4,441
First mortgage bonds and secured debt	637,559	487,541
Unsecured debt	101,676	199,644
Total long-term debt	743,541	691,626
Total long-term debt and common stockholders' equity	1,470,899	1,409,424
Current liabilities:
Accounts payable and accrued liabilities	46,371	66,559
Current maturities of long-term debt	418	714
Short-term debt		24,000
Regulatory liabilities	5,003	5,470
Customer deposits	12,276	12,001
Interest accrued	6,748	5,902
Other current liabilities	1,369
Unrealized loss in fair value of derivative contracts	2,612	3,403
Taxes accrued	11,703	2,992
Total current liabilities	86,500	121,041
Commitments and contingencies (Note 7)
Noncurrent liabilities and deferred credits:
Regulatory liabilities	133,895	131,888
Deferred income taxes	312,871	301,967
Unamortized investment tax credits	18,629	18,897
Pension and other postretirement benefit obligations	122,604	120,808
Unrealized loss in fair value of derivative contracts	4,362	3,819
Other	18,877	18,525
Total noncurrent liabilities and deferred credits	611,238	595,904
Total Capitalization and Liabilities	$ 2,168,637	$ 2,126,369