Note 14 - Termination of Deferred Compensation Plan (Details Textual) - 2015 Equity Incentive Plan [Member] $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($) shares
Deferred Compensation Arrangement with Individual, Shares Issued (in shares) \| shares	394,056
Deferred Compensation Arrangement with Individual, Compensation Expense \| $	$ 6.8

The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration