Note 2 - Acquisitions (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended
Apr. 01, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Business Combination, Acquisition Related Costs		$ 0	$ 10,871	$ 0	$ 11,322
HomeTown Bankshares Corporation [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares Issued Per Share Of Common Stock (in dollars per share)	$ 0.4150
Business Combination, Acquisition Related Costs				$ 0	$ 11,300

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=116868678&loc=d3e1043-128460

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration