Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Plant and property, at original cost:
Electric	$ 2,492,315	$ 2,473,927
Gas	84,586	83,402
Other	44,739	44,263
Construction work in progress	194,568	183,689
Total plant and property, Gross	2,816,208	2,785,281
Accumulated depreciation and amortization	779,891	764,895
Total plant and property, Net	2,036,317	2,020,386
Current assets:
Cash and cash equivalents	1,672	1,753
Restricted cash	4,727	4,726
Accounts receivable - trade, net of allowance $820 and $623, respectively	43,357	40,162
Accrued unbilled revenues	15,661	20,653
Accounts receivable - other	22,283	28,320
Fuel, materials and supplies	58,349	60,950
Prepaid expenses and other	8,070	8,835
Unrealized gain in fair value of derivative contracts	608	1,295
Regulatory assets	7,145	7,052
Total current assets	161,872	173,746
Noncurrent assets and deferred charges:
Regulatory assets	209,934	209,708
Goodwill	39,492	39,492
Unrealized gain in fair value of derivative contracts		16
Other	3,311	3,297
Total noncurrent assets and deferred charges	252,737	252,513
Total Assets	2,450,926	2,446,645
Capitalization and liabilities
Common stock, $1 par value, 43,911,310 and 43,820,726 shares issued and outstanding, respectively	43,911	43,821
Capital in excess of par value	660,364	657,466
Retained earnings	104,039	101,443
Total common stockholders' equity	808,314	802,730
Long-term debt (net of current portion):
Obligations under capital lease	3,500	3,580
First mortgage bonds and secured debt	724,996	724,838
Unsecured debt	100,949	100,935
Total long-term debt	829,445	829,353
Total long-term debt and common stockholders' equity	1,637,759	1,632,083
Current liabilities:
Accounts payable and accrued liabilities	43,477	66,946
Current maturities of long-term debt	25,267	25,246
Short-term debt	19,000	25,000
Regulatory liabilities	10,154	8,615
Customer deposits	14,793	14,623
Interest accrued	14,933	7,348
Unrealized loss in fair value of derivative contracts	4,743	4,472
Taxes accrued	9,076	2,832
Other current liabilities	297	323
Total current liabilities	$ 141,740	$ 155,405
Commitments and contingencies (Note 7)
Noncurrent liabilities and deferred credits:
Regulatory liabilities	$ 134,401	$ 132,457
Deferred income taxes	405,250	396,542
Unamortized investment tax credits	18,452	18,487
Pension and other postretirement benefit obligations	83,394	82,144
Unrealized loss in fair value of derivative contracts	3,873	3,696
Other	26,057	25,831
Total noncurrent liabilities	671,427	659,157
Total Capitalization and Liabilities	$ 2,450,926	$ 2,446,645