Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 30,312	$ 39,885
Receivables, net	32,736	32,662
Material and supplies	8,499	9,337
Prepaid expenses	4,068	3,598
Other current assets	2,102	3,481
Total current assets	77,717	88,963
Property, plant and equipment, net	579,107	565,956
Intangible assets, net	34,828	37,328
Goodwill	12,104	12,104
Deferred income taxes, net	89,896	88,466
Other assets	6,043	3,907
Total assets	799,695	796,724
Current liabilities
Current portion of long-term debt	3,000	3,000
Accounts payable	44,841	50,499
Accrued expenses	14,491	19,399
Advance billings and customer deposits	17,551	14,686
Other current liabilities	5,932	6,790
Total current liabilities	85,815	94,374
Long-term debt	283,046	284,179
Employee benefit obligations	104,597	99,366
Other liabilities	18,538	14,271
Total liabilities	$ 491,996	$ 492,190
Commitments and contingencies (Note 14)
Stockholders' equity
Common stock, par value of $0.01 per share, 245,000,000 shares authorized and 11,466,398 and 10,673,292 shares issued and outstanding at December 31, 2015 and 2014, respectively	$ 115	$ 107
Additional paid-in capital	178,019	170,521
Accumulated other comprehensive loss	(29,388)	(23,947)
Retained earnings	158,953	157,853
Total stockholders' equity	307,699	304,534
Total liabilities and stockholders' equity	$ 799,695	$ 796,724