Note 13 - Fair Value Measurements - Fair Value Adjustments for Assets Measured On a Nonrecurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net decrease in fair value:
Fair value adjustments	$ 148	$ 175
Impaired Loans [Member]
Net decrease in fair value:
Fair value adjustments	115	65
OREO [Member]
Net decrease in fair value:
Fair value adjustments	$ 33	$ 110