Note 6 - Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Amortization of right-of-use assets	$ 106	$ 110	$ 211	$ 219
Interest on lease liabilities	20	14	42	29
Operating lease cost	947	480	1,752	905
Short-term lease cost	217	313	407	575
Variable lease cost	40	35	82	75
Total lease cost	$ 1,330	$ 952	$ 2,494	$ 1,803

Amount of interest expense on finance lease liability.

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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Amount of amortization expense attributable to right-of-use asset from finance lease.

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Amount of lease cost recognized by lessee for lease contract.

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Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

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Amount of short-term lease cost, excluding expense for lease with term of one month or less.

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Amount of variable lease cost, excluded from lease liability, recognized when obligation for payment is incurred for finance and operating leases.

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