Note 9 - Off-balance Sheet Financial Instruments - Summary of Off-balance Sheet Financial Instruments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Commitments to Extend Credit [Member]
Contractual amounts with off-balance-sheet risk	$ 5,352
Construction Loans In Process [Member]
Contractual amounts with off-balance-sheet risk	21,408
Unused lines of Credit [Member]
Contractual amounts with off-balance-sheet risk	39,380
Standby Financial Letters of Credit [Member]
Contractual amounts with off-balance-sheet risk	1,961
Performance Standby Letters Of Credit [Member]
Contractual amounts with off-balance-sheet risk	378
Guaranteed Accounts [Member]
Contractual amounts with off-balance-sheet risk	$ 1,330