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Note 17 - Shareholders' Equity and Stock Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended	12 Months Ended
	Jan. 31, 2019	Dec. 19, 2018	May 10, 2017	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares				1,834,142
Proceeds from Issuance of Common Stock						$ 26,778
Fair Market Value Percentage Under Incentive Option Plan					100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant					152,000
Proceeds from Stock Options Exercised					$ 216	$ 245	$ 10
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross					0	0	0
Common Stock, Dividends, Per Share, Declared		$ 0.04
Dividends Payable, Date Declared		Jan. 11, 2019
Dividends Payable, Date of Record		Jan. 02, 2019
Restricted Stock [Member]
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense					$ 46
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition					2 years
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
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Per Year					20.00%
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition					2 years
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
Subsequent Event [Member] \| Bank of Commerce [Member] \| Merchants Holding Company [Member]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	10.00%			10.00%
Subsequent Event [Member] \| 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			$ 15,300
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans	85,300			85,300
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deposits	190,200			190,200
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Investment Securities	$ 107,400			$ 107,400