Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 40,759	$ 15,821
Receivables, net	32,229	33,377
Material and supplies	6,810	8,090
Prepaid expenses	4,899	4,093
Other current assets	1,328	7,229
Total current assets	86,025	68,610
Property, plant and equipment, net	608,298	595,997
Intangible assets, net	31,026	32,728
Goodwill	12,104	12,104
Deferred income taxes, net		92,171
Other assets	2,053	2,311
Total assets	739,506	803,921
Current liabilities
Current portion of long-term debt	10,250	3,000
Accounts payable	56,874	53,506
Accrued expenses	11,736	15,293
Advance billings and customer deposits	14,807	15,013
Other current liabilities	6,774	6,327
Total current liabilities	100,441	93,139
Long-term debt	299,066	281,699
Employee benefit obligations	79,953	105,930
Deferred income taxes, net	910
Other liabilities	38,927	18,239
Total liabilities	519,297	499,007
Commitments and contingencies (Note 13)
Stockholders’ equity
Common stock, par value of $0.01 per share, 245,000,000 shares authorized and 11,587,963 and 11,513,279 shares issued and outstanding at December 31, 2017 and 2016, respectively	116	115
Additional paid-in capital	182,689	179,958
Accumulated other comprehensive loss	(15,964)	(35,218)
Retained earnings	53,368	160,059
Total stockholders’ equity	220,209	304,914
Total liabilities and stockholders’ equity	$ 739,506	$ 803,921