Note 4 - Investment Securities - Schedule of Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value (Details) $ in Thousands	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	125	129
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (2)	$ (3)
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	370	532
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(83,121)	(98,020)
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	465,191	485,527
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	(83,123)	(98,023)
Debt Securities, Available-for-Sale, Unrealized Loss Position	$ 465,561	$ 486,059
US Treasury Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	1	1
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (2)	$ (3)
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	370	489
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	(2)	(3)
Debt Securities, Available-for-Sale, Unrealized Loss Position	$ 370	$ 489
Residential Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	108	112
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ 0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	43
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(74,529)	(88,547)
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	414,315	435,505
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	(74,529)	(88,547)
Debt Securities, Available-for-Sale, Unrealized Loss Position	$ 414,315	$ 435,548
Commercial Mortgage-Backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	1	1
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ 0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(59)	(123)
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,401	1,353
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	(59)	(123)
Debt Securities, Available-for-Sale, Unrealized Loss Position	$ 1,401	$ 1,353
Asset-Backed Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	3	3
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ 0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	(1)
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	20	25
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	0	(1)
Debt Securities, Available-for-Sale, Unrealized Loss Position	$ 20	$ 25
Corporate Bond Securities [Member]
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions	12	12
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ 0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(8,533)	(9,349)
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer	49,455	48,644
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	(8,533)	(9,349)
Debt Securities, Available-for-Sale, Unrealized Loss Position	$ 49,455	$ 48,644

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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