Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 28,228	$ 39,885
Receivables, net	34,053	32,662
Material and supplies	9,792	9,337
Prepaid expenses	5,334	3,598
Deferred income taxes	6,840	6,840
Other current assets	3,289	3,481
Total current assets	87,536	95,803
Property, plant and equipment, net	570,667	565,956
Intangible assets, net	36,079	37,328
Goodwill	12,104	12,104
Deferred income taxes	79,213	81,626
Other assets	10,513	9,151
Total assets	796,112	801,968
Current liabilities
Current portion of long-term debt	3,000	3,000
Accounts payable	45,797	50,499
Accrued expenses	16,102	19,399
Advance billings and customer deposits	15,354	14,686
Other current liabilities	7,488	6,790
Total current liabilities	87,741	94,374
Long-term debt	288,307	289,423
Employee benefit obligations	93,728	99,366
Other liabilities	15,774	14,271
Total liabilities	$ 485,550	$ 497,434
Commitments and contingencies (Note 11)
Stockholders' equity
Common stock, par value of $0.01 per share, 245,000,000 shares authorized and 11,005,434 and 10,673,292 shares issued and outstanding at June 30, 2015 and December 31, 2014, respectively	$ 110	$ 107
Additional paid-in capital	173,831	170,521
Accumulated other comprehensive loss	(22,664)	(23,947)
Retained earnings	159,285	157,853
Total stockholders' equity	310,562	304,534
Total liabilities and stockholders' equity	$ 796,112	$ 801,968