Note 3 - Mergers and Acquisitions - Cost and Allocation of Purchase Price (Details) - USD ($) $ / shares in Units, $ in Thousands	Nov. 30, 2018	Jan. 01, 2018	Dec. 31, 2019	Dec. 31, 2018
Net Assets Acquired:
Goodwill Resulting from Merger			$ 48,495	$ 49,488
Richland State Bancorp [Member]
Purchase Price:
Shares Issued to RSBI Shareholders on December 1, 2018 (in shares)	1,679,559
Closing Stock Price on November 30, 2018 (in dollars per share)	$ 25.29
Total Purchase Price	$ 42,476
Net Assets Acquired:
Cash and Cash Equivalents	40,648
Securities Available for Sale	63,823
Loans and Leases Receivable	190,802
Premises and Equipment, Net	5,282
Cash Value of Life Insurance	7,260
Core Deposit Intangible	3,947
Other Assets	4,668
Total Assets	316,430
Deposits	289,979
Other Liabilities	1,074
Total Liabilities	291,053
Net Assets Acquired	25,377
Goodwill Resulting from Merger	17,099
Net Assets Acquired	$ 25,377
Minden Bancorp [Member]
Purchase Price:
MBI Shares Cashed Out Under Terms of Merger		$ 2,409,107
Exchange Ratio (in dollars per share)		$ 23.20
Cash Paid to Shareholders for Shares of Common Stock		$ 55,891
Cash Paid on MBI Options		296
Total Purchase Price		56,187
Net Assets Acquired:
Cash and Cash Equivalents		15,891
Securities Available for Sale		99,867
Loans and Leases Receivable		192,714
Premises and Equipment, Net		2,678
Cash Value of Life Insurance		741
Core Deposit Intangible		2,494
Other Assets		3,055
Total Assets		317,440
Deposits		263,951
Borrowings		21,047
Other Liabilities		1,858
Total Liabilities		286,856
Net Assets Acquired		30,584
Goodwill Resulting from Merger		25,603
Net Assets Acquired		$ 30,584
Minden Bancorp [Member]
Purchase Price:
MBI Shares Outstanding at December 31, 2017 (in shares)		2,407,627
MBI Restricted Stock Awards Outstanding at December 31, 2017 (in shares)		1,480