Note 4 - Stock-based Compensation - Compensation Cost (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based compensation	$ 160	$ 161	$ 323	$ 319
Share-based Payment Arrangement, Option [Member]
Share-based compensation	126	119	250	221
Restricted Stock Units (RSUs) [Member]
Share-based compensation	$ 34	$ 42	$ 73	$ 98

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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