Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Assets
Cash and cash equivalents	$ 25,127	$ 24,353
Restricted cash	179	183
Short-term investments	15,876	20,562
Accounts receivable, net	7,553	8,323
Inventories	21,798	22,739
Other inventory supplies	8,000	8,208
Prepaid expenses and other current assets	920	1,035
Total current assets	79,453	85,403
Property and equipment, net	104,593	107,676
Other assets	1,604	1,827
Total assets	185,650	194,906
Liabilities and stockholders' equity
Accounts payable	2,640	3,754
Accrued payroll	249	514
Accrued and other current liabilities	1,174	925
Corporate income and franchise taxes	80	270
Accrued real estate taxes	335	280
Advance payments	7	10
Total current liabilities	4,485	5,753
Deferred tax liability	622	593
Total liabilities	5,107	6,346
Commitments and contingencies
Stockholders' equity
Preferred stock, $0.001 par value, 5,000,000 undesignated shares authorized, no shares issued or outstanding
Common stock, $0.001 par value, 40,000,000 shares authorized and 27,972,687 and 27,913,788 shares issued; 26,197,843 and 26,138,944 shares outstanding	28	28
Additional paid-in capital	372,644	372,319
Treasury stock, at cost, 1,774,844 shares	(12,148)	(12,148)
Accumulated other comprehensive loss	(37)	(43)
Accumulated deficit	(179,944)	(171,596)
Total stockholders' equity	180,543	188,560
Total liabilities and stockholders' equity	$ 185,650	$ 194,906