Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Plant and property, at original cost:
Electric	$ 2,063,208	$ 2,001,142
Natural gas	66,918	63,581
Water	11,540	11,128
Other	34,984	32,264
Construction work in progress	24,141	9,337
Total plant and property, Gross	2,200,791	2,117,452
Accumulated depreciation and amortization	637,139	598,363
Total plant and property, Net	1,563,652	1,519,089
Current assets:
Cash and cash equivalents	5,408	10,525
Restricted cash	4,357	1,771
Accounts receivable - trade, net of allowance of $1,138 and $865, respectively	42,296	41,380
Accrued unbilled revenues	20,326	23,595
Accounts receivable - other	16,269	25,445
Fuel, materials and supplies	62,239	45,557
Prepaid expenses and other	14,629	7,891
Regulatory assets	7,724	4,974
Total current assets	173,248	161,138
Noncurrent assets and deferred charges:
Regulatory assets	231,922	189,404
Goodwill	39,492	39,492
Unamortized debt issuance costs	9,331	9,257
Other	4,190	2,931
Total noncurrent assets and deferred charges	284,935	241,084
Total assets	2,021,835	1,921,311
Capitalization and liabilities
Common stock, $1 par value, 100,000,000 shares authorized, 41,977,725 and 41,576,869 shares issued and outstanding, respectively	41,978	41,577
Capital in excess of par value	618,304	610,579
Retained earnings	33,707	5,468
Total common stockholders' equity	693,989	657,624
Long-term debt (net of current portion)
Obligations under capital lease	4,739	4,995
First mortgage bonds and secured debt	487,948	488,577
Unsecured debt	199,572	199,500
Total long-term debt	692,259	693,072
Total long-term debt and common stockholders' equity	1,386,248	1,350,696
Current liabilities:
Accounts payable and accrued liabilities	59,307	58,820
Current maturities of long-term debt	933	881
Short-term debt	12,000	24,000
Customer deposits	11,428	11,061
Interest accrued	5,958	6,004
Other current liabilities		578
Unrealized loss in fair value of derivative contracts	4,769	760
Taxes accrued	2,634	3,935
Regulatory liabilities		1,243
Total current liabilities	97,029	107,282
Commitments and contingencies (Note 11)
Noncurrent liabilities and deferred credits:
Regulatory liabilities	128,440	87,579
Deferred income taxes	263,933	212,003
Unamortized investment tax credits	19,226	19,597
Pension and other postretirement benefit obligations	103,371	93,405
Unrealized loss in fair value of derivative contracts	5,081	3,564
Other	18,507	47,185
Total noncurrent liabilities and deferred credits	538,558	463,333
Total capitalization and liabilities	$ 2,021,835	$ 1,921,311