Note 10 - Acquisition - Assets and Liabilities Acquired (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended		12 Months Ended
	Jan. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Consideration paid:
Total consideration		$ 0	$ 34,907
Liabilities assumed:
Goodwill		$ 11,671		$ 11,671
Merchants Holding Company [Member]
Consideration paid:
Cash and fed funds sold				12,425
Investment securities				107,931
Loans, gross				87,570
Allowance for loan and lease losses				(1,286)
Interest receivable				688
Premises and equipment, net				378
Deferred tax assets, net				1,374
Federal Home Loan Bank of San Francisco stock				1,454
Life insurance				755
Other assets				371
Core deposit intangible				0
Total assets acquired				211,660
Liabilities assumed:
Demand, money market and savings				152,213
Certificates of deposit				38,003
Total deposits				190,216
Other liabilities				916
Total liabilities assumed				191,132
Net identifiable assets acquired over liabilities assumed				20,528
Merchants Holding Company [Member]
Consideration paid:
Cash	$ 15,300			15,300
Stock 1,834,142 shares at $10.69 per share				19,607
Total consideration				34,907
Cash and fed funds sold				12,425
Investment securities				107,380
Investment securities, adjustment				(551)
Loans, gross				85,278
Loans, gross, adjustment				(2,292)
Allowance for loan and lease losses				0
Allowance for loan and lease losses, adjustment				1,286
Interest receivable				688
Premises and equipment, net				2,234
Premises and equipment, net, adjustment				1,856
Deferred tax assets, net				22
Deferred tax assets, net, adjustment				(1,352)
Federal Home Loan Bank of San Francisco stock				1,454
Life insurance				755
Other assets				466
Other assets, adjustment				95
Core deposit intangible				4,353
Core deposit intangible, adjustment				4,353
Total assets acquired	211,700			215,055
Total assets acquired, adjustment				3,395
Liabilities assumed:
Demand, money market and savings				152,213
Certificates of deposit				38,003
Total deposits				190,216
Other liabilities				938
Other liabilities, adjustment				22
Total liabilities assumed				191,154
Total liabilities assumed, adjustment				22
Net identifiable assets acquired over liabilities assumed				23,901
Net identifiable assets acquired over liabilities assumed, adjustment				3,373
Goodwill	$ 11,000			$ 11,006