Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 86,464	$ 76,290
Accounts receivable, net	44,192	40,259
Inventory	31,474	26,080
Other current assets	4,925	5,221
Total current assets	167,055	147,850
Property, plant & equipment, net	96,817	92,999
Intangibles, net	10,409	11,798
Goodwill	15,714	15,714
Deferred tax assets, net	82,039	87,010
Other long-term assets	29,769	28,487
Total assets	401,803	383,858
Current liabilities
Current portion of long-term debt	2,750	2,750
Revolving line of credit	0	0
Accounts payable	15,313	17,464
Accrued expenses and other liabilities	25,186	26,536
Total current liabilities	43,249	46,750
Asset retirement obligations	10,992	10,412
Long-term debt, net	264,551	265,393
Other long-term liabilities	38,478	38,012
Total liabilities	357,270	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; 38,298 and 37,765 shares issued and outstanding, respectively)	383	378
Additional paid-in capital	235,882	232,960
Accumulated deficit	(190,702)	(209,013)
Accumulated other comprehensive loss	(1,030)	(1,034)
Total stockholders’ equity	44,533	23,291
Total liabilities and stockholders’ equity	$ 401,803	$ 383,858