Note 10 - Acquisition (Details Textual) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended
	Jan. 31, 2019	Jan. 31, 2019	Mar. 31, 2019	Mar. 31, 2018
Payments to Acquire Businesses, Gross	$ 15,300
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	1,834,142		1,834,142
Amortization of Intangible Assets, Total			$ 146	$ 55
Merchants Holding Company [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Total			211,660
Bank of Commerce [Member] | Merchants Holding Company [Member]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	10.00%	10.00%
Merchants Holding Company [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Total	$ 211,700	$ 211,700	215,015
Payments to Acquire Businesses, Gross		$ 15,300	15,300
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares		1,834,142
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
Goodwill, Ending Balance	11,000	$ 11,000	11,045
Goodwill, Amortization period		15 years
Impairment of Intangible Assets, Finite-lived			0
Business Acquisition, Transaction Costs			1,900
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual			940
Merchants Holding Company [Member] | Core Deposits [Member]
Finite-Lived Intangible Assets, Gross, Total	$ 4,400	$ 4,400
Finite-Lived Intangible Asset, Useful Life		8 years
Amortization of Intangible Assets, Total			$ 91