Note 9 - Acquisition (Details Textual)		3 Months Ended		9 Months Ended
	Jul. 01, 2021 USD ($) $ / shares shares	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Goodwill, Ending Balance		$ 19,628,000		$ 19,628,000		$ 19,628,000
Share Price (in dollars per share) | $ / shares	$ 54.10
Business Combination, Acquisition Related Costs		0	$ 2,201,000	0	$ 3,143,000
Landmark Bancorp Inc. [Member]
Number of Banks Held	1
Number of Bank Centers	5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets Including Goodwill	$ 375,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Receivables	298,860,000		298,860,000		298,860,000
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Deposits	308,500,000
Goodwill, Ending Balance	$ 12,575,000		12,575,000		12,575,000
Business Combination, Consideration Transferred, Equity Interests Issued And Issuable, Share Exchange Rate	0.272
Business Acquisition, Share Price (in dollars per share) | $ / shares	$ 3.26
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in shares) | shares	647,990
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	$ 35,056,259
Payments to Acquire Businesses, Gross	7,767,586
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Receivable, Gross Amortized Cost Basis	309,800,000		309,767,000		309,767,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Assets, Interest Rate Fair Value Adjustment, Homogeneous Loans	1,900,000				(1,855,000)
Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Financial Assets, Credit Fair Value Adjustment, Homogeneous Loans	$ 7,900,000				(7,915,000)
Number of Branches where Leases were Assumed	2
Number of Sold Participations Acquired	19
Business Combination, Acquisition Related Costs		$ 0	$ 2,200,000	$ 0	$ 3,100,000
Landmark Bancorp Inc. [Member] | Core Deposits [Member]
Finite-Lived Intangible Asset, Useful Life (Year)	10 years