Consolidated Balance Sheets - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 113,401,000	$ 76,290,000
Accounts receivable, net	43,753,000	40,259,000
Inventory	33,019,000	26,080,000
Other current assets	5,242,000	5,221,000
Total current assets	195,415,000	147,850,000
Property, plant and equipment, net	107,888,000	92,999,000
Intangibles, net	9,133,000	11,798,000
Goodwill	15,714,000	15,714,000
Deferred tax assets, net	81,449,000	87,010,000
Other long-term assets	30,232,000	28,487,000
Total assets	439,831,000	383,858,000
Current liabilities
Current portion of long-term debt	2,750,000	2,750,000
Revolving line of credit	0	0
Accounts payable	17,955,000	17,464,000
Accrued expenses and other liabilities	32,050,000	26,536,000
Total current liabilities	52,755,000	46,750,000
Asset retirement obligations	11,572,000	10,412,000
Long-term debt, net	263,709,000	265,393,000
Other long-term liabilities	40,793,000	38,012,000
Total liabilities	368,829,000	360,567,000
Commitments and contingencies (see Note 15)
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; 38,466 and 37,765 shares issued and outstanding, respectively)	385,000	378,000
Additional paid-in capital	239,865,000	232,960,000
Accumulated deficit	(168,140,000)	(209,013,000)
Accumulated other comprehensive loss	(1,108,000)	(1,034,000)
Total stockholders’ equity	71,002,000	23,291,000
Total liabilities and stockholders’ equity	$ 439,831,000	$ 383,858,000