Note 6 - Derivative and Hedging Transactions - Effect of Fair Value and Cash Flow Hedge Accounting on the Consolidated Statements of Income and Comprehensive Income (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
Amount of gain or (loss) reclassified from accumulated other comprehensive income into income	$ (2)
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income Excluded Component
Interest Rate Contract [Member] | Interest Income [Member]
Total amounts of income and expense line items presented in the cash flow statement of financial performance in which the effects of fair value or hedges are recorded
Amount of gain or (loss) reclassified from accumulated other comprehensive income into income
Amount of gain or (loss) reclassified from accumulated other comprehensive income into income as a result that a forecasted transaction is no longer probable of occurring
Amount of gain or (loss) reclassified from accumulated OCI into income - included component
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income Excluded Component
Interest Rate Contract [Member] | Interest Expense [Member]
Total amounts of income and expense line items presented in the cash flow statement of financial performance in which the effects of fair value or hedges are recorded	2
Amount of gain or (loss) reclassified from accumulated other comprehensive income into income	2
Amount of gain or (loss) reclassified from accumulated other comprehensive income into income as a result that a forecasted transaction is no longer probable of occurring
Amount of gain or (loss) reclassified from accumulated OCI into income - included component	2
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income Excluded Component