Note 9 - Share-based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Stock-based compensation	$ 779	$ 746
Share-based Payment Arrangement, Option [Member]
Stock-based compensation	500	447
Restricted Stock Units (RSUs) [Member]
Stock-based compensation	$ 279	$ 299

Amount of noncash expense for share-based payment arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

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Balance Type:	debit
Period Type:	duration