Note 6 - Long-term Debt - Balance of Future Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Long-term debt	$ 25,147
Long-term debt, current portion	4,630	$ 8,611
Long-term debt, net of current portion	20,517	$ 3,380
Site Readiness Agreement [Member]
Long-term debt	899
Long-term debt, current portion	463
Long-term debt, net of current portion	$ 436

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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