Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Plant and property, at original cost:
Electric	$ 2,682,604	$ 2,473,927
Gas	85,309	83,402
Other	44,988	44,263
Construction work in progress	26,365	183,689
Total plant and property, Gross	2,839,266	2,785,281
Accumulated depreciation and amortization	790,683	764,895
Total plant and property, Net	2,048,583	2,020,386
Current assets:
Cash and cash equivalents	1,619	1,753
Restricted cash	4,727	4,726
Accounts receivable - trade, net of allowance $460 and $623, respectively	41,511	40,162
Accrued unbilled revenues	23,361	20,653
Accounts receivable - other	16,603	28,320
Fuel, materials and supplies	57,735	60,950
Prepaid expenses and other	8,378	8,835
Unrealized gain in fair value of derivative contracts	6,234	1,295
Regulatory assets	7,120	7,052
Total current assets	167,288	173,746
Noncurrent assets and deferred charges:
Regulatory assets	209,682	209,708
Goodwill	39,492	39,492
Unrealized gain in fair value of derivative contracts	410	16
Other	3,180	3,297
Total noncurrent assets and deferred charges	252,764	252,513
Total Assets	2,468,635	2,446,645
Capitalization and liabilities
Common stock, $1 par value, 44,024,803 and 43,820,726 shares issued and outstanding, respectively	44,025	43,821
Capital in excess of par value	662,477	657,466
Retained earnings	101,821	101,443
Total common stockholders' equity	808,323	802,730
Long-term debt (net of current portion):
Obligations under capital lease	3,418	3,580
First mortgage bonds and secured debt	725,155	724,838
Unsecured debt	100,964	100,935
Total long-term debt	829,537	829,353
Total long-term debt and common stockholders' equity	1,637,860	1,632,083
Current liabilities:
Accounts payable and accrued liabilities	45,628	66,946
Current maturities of long-term debt	25,289	25,246
Short-term debt	30,500	25,000
Regulatory liabilities	12,290	8,615
Customer deposits	15,016	14,623
Interest accrued	7,642	7,348
Unrealized loss in fair value of derivative contracts	1,175	4,472
Taxes accrued	13,619	2,832
Other current liabilities	272	323
Total current liabilities	151,431	155,405
Commitments and contingencies (Note 7)
Noncurrent liabilities and deferred credits:
Regulatory liabilities	142,017	132,457
Deferred income taxes	410,922	396,542
Unamortized investment tax credits	18,432	18,487
Pension and other postretirement benefit obligations	78,513	82,144
Unrealized loss in fair value of derivative contracts	2,676	3,696
Other	26,784	25,831
Total noncurrent liabilities	679,344	659,157
Total Capitalization and Liabilities	$ 2,468,635	$ 2,446,645