Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 28,845	$ 39,885
Receivables, net	33,580	32,662
Material and supplies	9,126	9,337
Prepaid expenses	5,085	3,598
Deferred income taxes	6,481	6,840
Other current assets	3,633	3,481
Total current assets	86,750	95,803
Property, plant and equipment, net	572,242	565,956
Intangible assets, net	35,454	37,328
Goodwill	12,104	12,104
Deferred income taxes	82,917	81,626
Other assets	10,133	9,151
Total assets	799,600	801,968
Current liabilities
Current portion of long-term debt	3,000	3,000
Accounts payable	44,707	50,499
Accrued expenses	15,331	19,399
Advance billings and customer deposits	16,540	14,686
Other current liabilities	6,630	6,790
Total current liabilities	86,208	94,374
Long-term debt	287,752	289,423
Employee benefit obligations	102,762	99,366
Other liabilities	17,467	14,271
Total liabilities	494,189	497,434
Stockholders' equity
Common stock, par value of $0.01 per share, 245,000,000 shares authorized and 11,122,880 and 10,673,292 shares issued and outstanding at September 30, 2015 and December 31, 2014, respectively	111	107
Additional paid-in capital	174,005	170,521
Accumulated other comprehensive loss	(28,094)	(23,947)
Retained earnings	159,389	157,853
Total stockholders' equity	305,411	304,534
Total liabilities and stockholders' equity	$ 799,600	$ 801,968