CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 40,955	$ 26,271
Restricted cash	5,000	5,000
Short-term investments	583	2,350
Accounts receivable, net of allowance for doubtful accounts of $250 at December 31, 2020 and 2019	7,343	24,356
Current maturities of notes receivable		66
Prepaid expenses and other current assets	4,709	7,575
Total current assets	58,590	65,618
Property and equipment	271,480	284,647
Less accumulated depreciation	(232,580)	(231,098)
Property and equipment, net	38,900	53,549
Right-of-use assets	5,494	6,605
Notes receivable, net of current maturities		1,394
Intangibles, net	393	385
Long-term deferred tax assets, net		57
Total assets	103,377	127,608
Current liabilities:
Accounts payable	1,603	3,952
Accrued liabilities:
Payroll costs and other taxes	1,045	1,963
Other	1,811	3,599
Deferred revenue	1,779	3,481
Current maturities of notes payable and finance leases	94	4,062
Current maturities of operating lease liabilities	1,109	1,200
Total current liabilities	7,441	18,257
Long-term liabilities:
Notes payable and finance leases, net of current maturities	44	96
Operating lease liabilities, net of current maturities	4,899	5,940
Deferred tax liabilities, net	19
Other accrued liabilities		150
Total long-term liabilities	4,962	6,186
Operating commitments and contingencies
Stockholders' equity:
Preferred stock-par value $1.00 per share; 4,000,000 shares authorized, none outstanding
Common stock-par value $0.01 per share; 35,000,000 shares authorized, 23,526,517 and 23,335,855 shares issued, and 23,478,072 and 23,287,410 shares outstanding at December 31, 2020 and 2019, respectively	235	233
Additional paid-in capital	154,866	154,235
Retained deficit	(62,927)	(49,731)
Treasury stock, at cost; 48,445 shares
Accumulated other comprehensive loss, net	(1,200)	(1,572)
Total stockholders' equity	90,974	103,165
Total liabilities and stockholders' equity	$ 103,377	$ 127,608