Note 5 - Investment Securities (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Equity Securities without Readily Determinable Fair Value, Amount	$ 15,800	$ 800
Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Cumulative Amount	0
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Cumulative Amount	0
Equity Securities without Readily Determinable Fair Value, Downward Price Adjustment, Annual Amount	0	0
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount	0	0
Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount	0	0
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Cumulative Amount	0
Collateralized Loan Obligations [Member]
Other than Temporary Impairment Losses, Investments, Total	$ 4,200	$ 0