Note 3 - Debt Securities - Debt and Equity Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Available-for-sale, amortized cost	$ 972,315	$ 972,315	$ 906,135
Securities, Available-for-sale, Gross Unrealized Gains	1		5,645
Securities, Available-for-sale, Gross Unrealized Losses	149,504		14,195
Debt Securities, Available-for-Sale, Total	822,812	$ 822,812	897,585
US Treasury and Other US Government Agencies Debt Securities [Member]
Available-for-sale, amortized cost	7,353		7,320
Securities, Available-for-sale, Gross Unrealized Gains	0		0
Securities, Available-for-sale, Gross Unrealized Losses	856		99
Debt Securities, Available-for-Sale, Total	6,497		7,221
US Government-sponsored Enterprises Debt Securities [Member]
Available-for-sale, amortized cost	177,261		163,700
Securities, Available-for-sale, Gross Unrealized Gains	0		20
Securities, Available-for-sale, Gross Unrealized Losses	32,049		4,490
Debt Securities, Available-for-Sale, Total	145,212		159,230
Collateralized Mortgage-Backed Securities [Member]
Available-for-sale, amortized cost	518,727		465,588
Securities, Available-for-sale, Gross Unrealized Gains	1		2,726
Securities, Available-for-sale, Gross Unrealized Losses	74,290		6,537
Debt Securities, Available-for-Sale, Total	444,438		461,777
Asset-Backed Securities [Member]
Available-for-sale, amortized cost	47,538		46,583
Securities, Available-for-sale, Gross Unrealized Gains	0		213
Securities, Available-for-sale, Gross Unrealized Losses	2,288		83
Debt Securities, Available-for-Sale, Total	45,250		46,713
Corporate Debt Securities [Member]
Available-for-sale, amortized cost	2,500		2,500
Securities, Available-for-sale, Gross Unrealized Gains	0		75
Securities, Available-for-sale, Gross Unrealized Losses	97		0
Debt Securities, Available-for-Sale, Total	2,403		2,575
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale, amortized cost	218,936		220,444
Securities, Available-for-sale, Gross Unrealized Gains	0		2,611
Securities, Available-for-sale, Gross Unrealized Losses	39,924		2,986
Debt Securities, Available-for-Sale, Total	$ 179,012		$ 220,069

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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