Note 12 - Fair Value Measurement and Disclosure - Quantitative Information About Assets Measured at Fair Value (Details) - Fair Value, Inputs, Level 3 [Member] $ in Thousands	Mar. 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	$ 214,392	$ 78,926
Impaired loans, net	$ 438,883	$ 662,799
Valuation, Market Approach [Member] | Measurement Input, Appraised Value [Member] | Minimum [Member]
Foreclosed assets range	(38)	(36)
Impaired loans, net range	(46)	(44)
Valuation, Market Approach [Member] | Measurement Input, Appraised Value [Member] | Maximum [Member]
Foreclosed assets range	(56)	49
Impaired loans, net range	(100)	69
Valuation, Income Approach [Member] | Payment Stream [Member]
Impaired loans, net	$ 3,098	$ 54,199