Note 13 - Fair Value Measurements - Quantitative Information About Unobservable Inputs for Assets Measured on a Nonrecurring Basis Using Level 3 Measurements (Details) - Fair Value, Inputs, Level 3 [Member] - Valuation, Market Approach [Member] $ in Thousands	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Collateral-dependent impaired loans, fair value	$ 5,434	$ 8,885
OREO, fair value	$ 1,074	$ 4,446
Measurement Input, Discount for Lack of Marketability [Member]
Collateral-dependent impaired loans, measurement input
Measurement Input, Discount for Lack of Marketability [Member] | Weighted Average [Member]
Collateral-dependent impaired loans, measurement input		0.031
OREO, measurement input	0.053	0.04
Measurement Input, Discount for Lack of Marketability [Member] | Minimum [Member]
Collateral-dependent impaired loans, measurement input		0
OREO, measurement input	0	0
Measurement Input, Discount for Lack of Marketability [Member] | Maximum [Member]
Collateral-dependent impaired loans, measurement input		0.228
OREO, measurement input	0.06	0.717