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Note 16 - Shareholders' Equity and Stock Plans (Details Textual) - USD ($)				1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 18, 2019	Jan. 31, 2019	May 10, 2017	Jan. 31, 2019	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares						1,834,142
Proceeds from Issuance of Common Stock						$ (1,010,000)
Stock Repurchased and Retired During Period, Value					$ 1,000,000	$ 1,010,000
Stock Repurchased and Retired During Period, Shares					90,501
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant					486,900	486,900
Proceeds from Stock Options Exercised						$ 52,000	216,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross						0
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount					$ 0	$ 0
Common Stock, Dividends, Per Share, Declared	$ 0.05
Dividends Payable, Date Declared	Jan. 10, 2020
Dividends Payable, Date of Record	Dec. 31, 2019
Restricted Stock [Member]
Share-based Payment Arrangement, Expense, Tax Benefit						$ 9,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition						1 year
Share-based Payment Arrangement, Expense						$ 414,000	288,000
Restricted Stock [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period						3 years
Restricted Stock [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period						5 years
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition						2 years
Share-based Payment Arrangement, Expense						$ 0	$ 8,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Per Year						20.00%
Public Offering [Member]
Stock Issued During Period, Shares, New Issues			2,738,096
Share Price			$ 10.50
Proceeds from Issuance of Common Stock			$ 26,800,000
Bank of Commerce [Member] \| Merchants Holding Company [Member]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		10.00%		10.00%
Merchants Holding Company [Member]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares		1,834,142		1,834,142
Payments to Acquire Businesses, Gross		$ 15,300,000		$ 15,300,000		$ 15,300,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deposits		190,200,000		190,200,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans		85,300,000		85,300,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Investment Securities		$ 107,400,000		$ 107,400,000