Note 7 - Derivatives and Hedging Activities - Significantly Impact of operations (Details) - Interest rate swap - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fee Income On Derivative Contracts	$ 28,300	$ 10,800	$ 3,100
Not Designated as Hedging Instrument [Member]
Derivative Asset, Notional Amount	787,221	445,022
Derivative Assets	84,679	22,196
Derivative Liability, Notional Amount	787,221	445,022
Derivative Liabilities	$ 84,679	$ 22,196