Note 15 - Financial Derivatives - Cash Flow Swap Hedges (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Net change in unrealized holding (loss)/gain on cash flow hedge derivatives				$ (1,323,000)	$ 5,803,000
Fair Value Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Notional		$ 857,341,000	$ 874,034,000	$ 857,341,000	$ 874,034,000
Weighted average fixed rate-pay		1.80%	2.12%	1.80%	2.12%
Weighted average variable rate spread		0.27%	0.68%	0.27%	0.68%
Weighted average variable rate-receive		5.33%	2.61%	5.33%	2.61%
Net change in unrealized holding (loss)/gain on cash flow hedge derivatives				$ 27,378	$ 38,589
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Notional		$ 56,000,000		56,000,000		$ 50,000,000
Periodic net settlement of swaps	[1]	$ 7,659,000	$ 1,461,000	$ 21,065,000	$ (1,628,000)

[1] the amount of periodic net settlement of interest rate swaps was included in interest expense.