Note 3 - Investment Securities - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	$ 603,221	$ 686,556
Unrealized Gains, Available-for-sale	765	19
Unrealized Losses, Available-for-sale	(72,972)	(98,522)
Allowance for Credit Losses, Available-for-sale	0	0
Available-for-sale, at fair value (amortized cost of $603,221 and $686,556, respectively)	531,014	588,053
Amortized Cost, Held-to-maturity	259,351
Unrealized Gains, Held-to-maturity	0	0
Unrealized Losses, Held-to-maturity	(28,754)	(38,730)
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	126	131
Debt Securities, Held-to-maturity, Fair Value	230,597	236,986
Amortized Cost, Total investment securities	862,572	962,272
Unrealized Gains, Total investment securities	765	19
Unrealized Losses, Total investment securities	(101,726)	(137,252)
Allowance for Credit Losses, Total investment securities	126	131
Fair Value, Total investment securities	761,611	825,039
US Treasury Securities [Member]
Unrealized Gains, Available-for-sale	0	18
Unrealized Losses, Available-for-sale	(2)	(2)
Allowance for Credit Losses, Available-for-sale	0	0
Available-for-sale, at fair value (amortized cost of $603,221 and $686,556, respectively)	446	30,707
Residential Mortgage-Backed Securities [Member]
Unrealized Gains, Available-for-sale	765	1
Unrealized Losses, Available-for-sale	(69,173)	(92,805)
Allowance for Credit Losses, Available-for-sale	0	0
Available-for-sale, at fair value (amortized cost of $603,221 and $686,556, respectively)	479,837	503,706
Unrealized Gains, Held-to-maturity	0	0
Unrealized Losses, Held-to-maturity	(21,535)	(27,092)
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	51	54
Debt Securities, Held-to-maturity, Fair Value	124,331	129,001
Commercial Mortgage-Backed Securities [Member]
Unrealized Gains, Available-for-sale	0	0
Unrealized Losses, Available-for-sale	(50)	(99)
Allowance for Credit Losses, Available-for-sale	0	0
Available-for-sale, at fair value (amortized cost of $603,221 and $686,556, respectively)	1,279	1,251
Asset-Backed Securities [Member]
Unrealized Gains, Available-for-sale	0	0
Unrealized Losses, Available-for-sale	0	0
Allowance for Credit Losses, Available-for-sale	0	0
Available-for-sale, at fair value (amortized cost of $603,221 and $686,556, respectively)	16	19
Corporate Bond Securities [Member]
Unrealized Gains, Available-for-sale	0	0
Unrealized Losses, Available-for-sale	(3,747)	(5,616)
Allowance for Credit Losses, Available-for-sale	0	0
Available-for-sale, at fair value (amortized cost of $603,221 and $686,556, respectively)	49,436	52,370
US States and Political Subdivisions Debt Securities [Member]
Unrealized Gains, Held-to-maturity	0	0
Unrealized Losses, Held-to-maturity	(7,219)	(11,638)
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest	75	77
Debt Securities, Held-to-maturity, Fair Value	106,266	107,985
Reported Value Measurement [Member]
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	603,221	686,556
Amortized Cost, Held-to-maturity	259,351	275,716
Reported Value Measurement [Member] | US Treasury Securities [Member]
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	448	30,691
Reported Value Measurement [Member] | Residential Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	548,245	596,510
Amortized Cost, Held-to-maturity	145,866	156,093
Reported Value Measurement [Member] | Commercial Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	1,329	1,350
Reported Value Measurement [Member] | Asset-Backed Securities [Member]
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	16	19
Reported Value Measurement [Member] | Corporate Bond Securities [Member]
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	53,183	57,986
Reported Value Measurement [Member] | US States and Political Subdivisions Debt Securities [Member]
Amortized Cost, Held-to-maturity	$ 113,485	$ 119,623