Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 19,191	$ 40,759
Receivables, net	24,119	32,229
Material and supplies	6,805	6,810
Prepaid expenses	4,187	4,899
Other current assets	3,639	1,328
Total current assets	57,941	86,025
Property, plant and equipment, net	607,087	608,298
Intangible assets, net	30,699	31,026
Goodwill	12,104	12,104
Other assets	6,512	2,053
Total assets	714,343	739,506
Current liabilities
Current portion of long-term debt	10,250	10,250
Accounts payable	53,290	56,874
Accrued expenses	11,832	11,736
Advance billings and customer deposits	9,349	14,807
Other current liabilities	3,934	6,774
Total current liabilities	88,655	100,441
Long-term debt	294,804	299,066
Employee benefit obligations	78,036	79,953
Deferred income taxes, net	910	910
Other liabilities	33,638	38,927
Total liabilities	496,043	519,297
Commitments and contingencies (Note 11)
Stockholders’ equity
Common stock, par value of $0.01 per share, 245,000,000 shares authorized and 11,635,116 and 11,587,963 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	116	116
Additional paid-in capital	182,546	182,689
Accumulated other comprehensive loss	(16,053)	(15,964)
Retained earnings	51,691	53,368
Total stockholders’ equity	218,300	220,209
Total liabilities and stockholders’ equity	$ 714,343	$ 739,506