Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 73,739	$ 76,290
Accounts receivable, net	47,834	40,259
Inventory	32,086	26,080
Other current assets	5,598	5,221
Total current assets	159,257	147,850
Property, plant & equipment, net	93,777	92,999
Intangibles, net	11,106	11,798
Goodwill	15,714	15,714
Deferred tax assets, net	83,655	87,010
Other long-term assets	29,080	28,487
Total assets	392,589	383,858
Current liabilities
Current portion of long-term debt	2,750	2,750
Revolving line of credit	0	0
Accounts payable	21,012	17,464
Accrued expenses and other liabilities	21,634	26,536
Total current liabilities	45,396	46,750
Asset retirement obligations	10,702	10,412
Long-term debt, net	264,972	265,393
Other long-term liabilities	37,855	38,012
Total liabilities	358,925	360,567
Commitments and contingencies (See Note 13)
Stockholders’ equity
Preferred stock ($0.01 par value, 25,000 shares authorized; no shares issued and outstanding)	0	0
Common stock ($0.01 par value, 250,000 shares authorized; 37,997 and 37,765 shares issued and outstanding, respectively)	380	378
Additional paid-in capital	234,765	232,960
Accumulated deficit	(200,447)	(209,013)
Accumulated other comprehensive loss	(1,034)	(1,034)
Total stockholders’ equity	33,664	23,291
Total liabilities and stockholders’ equity	$ 392,589	$ 383,858