Note 7 - Derivatives and Hedging Activities - Significantly Impact of operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Assets	$ 222,757	$ 87,827
Derivative Liabilities	229,270	88,437
Interest rate swap
Derivative Assets	222,431	84,679
Derivative Liabilities	222,431	84,679
Fee Income On Derivative Contracts	74,800	28,300	$ 10,800
Not Designated as Hedging Instrument | Interest rate swap
Derivative Asset, Notional Amount	1,539,602	787,221
Derivative Assets	222,431	84,679
Derivative Liability, Notional Amount	1,539,602	787,221
Derivative Liabilities	$ 222,431	$ 84,679