Note 15 - Fair Values Measurements and Disclosures - Quantitative Information About Assets Measured at Fair Value (Details) - Fair Value, Inputs, Level 3 [Member] $ in Thousands	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Measurement Input, Discount Rate [Member]
Impaired loans, net range	10	10
Valuation, Market Approach [Member] | Measurement Input, Appraised Value [Member]
Foreclosed assets	$ 12,926	$ 78,926
Impaired loans, net	$ 287,815	$ 662,799
Impaired loans, net range	(46.67)
Valuation, Market Approach [Member] | Measurement Input, Appraised Value [Member] | Minimum [Member]
Foreclosed assets range	(50)	(36)
Impaired loans, net range		(44)
Valuation, Market Approach [Member] | Measurement Input, Appraised Value [Member] | Maximum [Member]
Foreclosed assets range	(76)	(49)
Impaired loans, net range		(69)
Valuation, Income Approach [Member] | Payment Stream [Member]
Impaired loans, net	$ 63,421	$ 54,199