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Note 8 - Business Combination (Details Textual)			3 Months Ended
	Jul. 01, 2020 USD ($) shares	Oct. 01, 2019 USD ($) shares	Mar. 31, 2021 USD ($)
County Bank Corp ("County") [Member]
Number of Branch Offices		14
Number of Loan Office		1
Community Shores Bank Corp ("Community Shores") [Member]
Number of Branch Offices	4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Total	$ 244,535,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Total Loans	174,800,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Total Deposits	$ 227,832,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in shares) | shares	524,139
Business Acquisition, Equity Interest Issued or Issuable, Number of Fractional Shares (in shares) | shares	84
Payments to Acquire Businesses, Gross	$ 5,390,000
Business Combination, Consideration Transferred, Total	$ 20,881,000
Business Combination, Provisional Information Initial Accounting Incomplete Adjustment, Loans			$ 828,000
Business Combination, Provisional Information Initial Accounting Incomplete Adjustment, Other Assets			(268,000)
Goodwill, Purchase Accounting Adjustments			$ (560,000)
County Bank Corp ("County") [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Total		$ 672,762,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Total Loans		424,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Total Deposits		573,601,000
Business Combination, Consideration Transferred, Total		$ 107,945,000
County Bank Corp ("County") [Member] | Common Stock [Member]
Stock Issued During Period, Shares, Acquisitions (in shares) | shares		3,603,872
Stock Issued During Period, Value, Acquisitions		$ 108,000,000
County Bank Corp ("County") [Member] | Fractional Stock [Member]
Stock Issued During Period, Shares, Acquisitions (in shares) | shares		299

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- Definition

Number of fractional shares of equity interests issued or issuable to acquire entity.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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