Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Plant and property, at original cost:
Electric	$ 2,473,927	$ 2,420,824
Gas	83,402	79,364
Other	44,263	41,394
Construction work in progress	183,689	112,097
Total plant and property, Gross	2,785,281	2,653,679
Accumulated depreciation and amortization	764,895	743,407
Total plant and property, Net	2,020,386	1,910,272
Current assets:
Cash and cash equivalents	1,753	2,105
Restricted cash	4,726	4,726
Accounts receivable - trade, net of allowance $623 and $1,021, respectively	40,162	45,444
Accrued unbilled revenues	20,653	25,945
Accounts receivable - other	28,320	41,256
Fuel, materials and supplies	60,950	57,799
Prepaid expenses and other	8,835	8,679
Unrealized gain in fair value of derivative contracts	1,295	3,901
Regulatory assets	7,052	10,752
Total current assets	173,746	200,607
Noncurrent assets and deferred charges:
Regulatory assets	209,708	209,717
Goodwill	39,492	39,492
Unamortized debt issuance costs	8,658	8,821
Unrealized gain in fair value of derivative contracts	16
Other	3,297	2,147
Total noncurrent assets and deferred charges	261,171	260,177
Total Assets	2,455,303	2,371,056
Capitalization and liabilities
Common stock, $1 par value, 43,820,726 and 43,479,186 shares issued and outstanding, respectively	43,821	43,479
Capital in excess of par value	657,466	649,543
Retained earnings	101,443	90,276
Total common stockholders' equity	802,730	783,298
Long-term debt (net of current portion):
Obligations under capital lease	3,580	3,875
First mortgage bonds and secured debt	732,653	697,615
Unsecured debt	101,714	101,699
Total long-term debt	837,947	803,189
Total long-term debt and common stockholders' equity	1,640,677	1,586,487
Current liabilities:
Accounts payable and accrued liabilities	66,946	83,420
Current maturities of long-term debt	25,310	292
Short-term debt	25,000	44,000
Regulatory liabilities	8,615	7,898
Customer deposits	14,623	13,747
Interest accrued	7,348	6,565
Unrealized loss in fair value of derivative contracts	4,472	6,469
Taxes accrued	2,832	3,380
Other current liabilities	323	206
Total current liabilities	$ 155,469	$ 165,977
Commitments and contingencies (Note 7)
Noncurrent liabilities and deferred credits:
Regulatory liabilities	$ 132,457	$ 128,471
Deferred income taxes	396,542	358,252
Unamortized investment tax credits	18,487	18,517
Pension and other postretirement benefit obligations	82,144	93,863
Unrealized loss in fair value of derivative contracts	3,696	3,243
Other	25,831	16,246
Total noncurrent liabilities	659,157	618,592
Total Capitalization and Liabilities	$ 2,455,303	$ 2,371,056