Note 6 - Goodwill and Intangible Assets (Details Textual) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill, Ending Balance	$ 60,506,000	$ 52,870,000	$ 13,728,000
Goodwill, Impairment Loss	0
Amortization of Intangible Assets, Total	1,498,000	353,000	$ 0
Core Deposits [Member]
Amortization of Intangible Assets, Total	1,498,000	$ 353,000
Valley Ridge Financial Corp. [Member]
Goodwill, Ending Balance	13,700,000
County Bank Corp [Member]
Goodwill, Ending Balance	$ 38,900,000
County Bank Corp [Member] \| Core Deposits [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)	10 years
Community Shores Bank Corporation [Member]
Goodwill, Ending Balance	$ 7,900,000
Community Shores Bank Corporation [Member] \| Core Deposits [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)	8 years

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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