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Note 3 - Debt Securities Available for Sale and Held to Maturity - Gross Unrealized Losses, Investment Securities Portfolio (Details) $ in Thousands	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Available for sale securities, less than 12 months, number of investment positions	42	22
Held to Maturity securities, less than 12 months, number of investment positions	3	47
Available for sale securities, less than 12 months, fair value	$ 278,653	$ 66,670
Held to Maturity securities, less than 12 months, fair value	5,070	267,612
Available for sale securities, less than 12 months, unrealized loss	(2,627)	(692)
Held to Maturity securities, less than 12 months, unrealized loss	$ (9)	$ (4,308)
Available for sale securities, 12 months or longer, number of investment positions	291	332
Held to Maturity securities, 12 months or longer, number of investment positions	110	141
Available for sale securities, 12 months or longer, fair value	$ 2,383,031	$ 2,653,765
Held to Maturity securities, 12 months or longer, fair value	434,944	530,005
Available for sale securities, 12 months or longer, unrealized loss	(140,591)	(238,759)
Held to Maturity securities, 12 months or longer, unrealized loss	$ (11,926)	$ (32,524)
Available for sale securities, total, number of investment positions	333	354
Held to Maturity securities, total, number of investment positions	113	188
Available for sale securities, total, fair value	$ 2,661,684	$ 2,720,435
Held to Maturity securities, total, fair value	440,014	797,617
Available for sale securities, total, unrealized loss	(143,218)	(239,451)
Held to Maturity securities, total, unrealized loss	$ (11,935)	$ (36,832)
Agency Residential MBS [Member]
Available for sale securities, less than 12 months, number of investment positions	5	12
Held to Maturity securities, less than 12 months, number of investment positions	0	0
Available for sale securities, less than 12 months, fair value	$ 18,550	$ 18,030
Held to Maturity securities, less than 12 months, fair value	0	0
Available for sale securities, less than 12 months, unrealized loss	(337)	(471)
Held to Maturity securities, less than 12 months, unrealized loss	$ 0	$ 0
Available for sale securities, 12 months or longer, number of investment positions	104	103
Held to Maturity securities, 12 months or longer, number of investment positions	63	80
Available for sale securities, 12 months or longer, fair value	$ 173,381	$ 192,963
Held to Maturity securities, 12 months or longer, fair value	42,819	52,771
Available for sale securities, 12 months or longer, unrealized loss	(11,108)	(17,520)
Held to Maturity securities, 12 months or longer, unrealized loss	$ (2,566)	$ (4,218)
Available for sale securities, total, number of investment positions	109	115
Held to Maturity securities, total, number of investment positions	63	80
Available for sale securities, total, fair value	$ 191,931	$ 210,993
Held to Maturity securities, total, fair value	42,819	52,771
Available for sale securities, total, unrealized loss	(11,445)	(17,991)
Held to Maturity securities, total, unrealized loss	$ (2,566)	$ (4,218)
US States and Political Subdivisions Debt Securities [Member]
Available for sale securities, less than 12 months, number of investment positions	1	2
Held to Maturity securities, less than 12 months, number of investment positions	1	24
Available for sale securities, less than 12 months, fair value	$ 1,311	$ 2,764
Held to Maturity securities, less than 12 months, fair value	365	15,822
Available for sale securities, less than 12 months, unrealized loss	(2)	(21)
Held to Maturity securities, less than 12 months, unrealized loss	$ 0	$ (78)
Available for sale securities, 12 months or longer, number of investment positions	30	40
Held to Maturity securities, 12 months or longer, number of investment positions	20	26
Available for sale securities, 12 months or longer, fair value	$ 40,371	$ 51,759
Held to Maturity securities, 12 months or longer, fair value	18,465	25,814
Available for sale securities, 12 months or longer, unrealized loss	(571)	(1,680)
Held to Maturity securities, 12 months or longer, unrealized loss	$ (45)	$ (299)
Available for sale securities, total, number of investment positions	31	42
Held to Maturity securities, total, number of investment positions	21	50
Available for sale securities, total, fair value	$ 41,682	$ 54,523
Held to Maturity securities, total, fair value	18,830	41,636
Available for sale securities, total, unrealized loss	(573)	(1,701)
Held to Maturity securities, total, unrealized loss	$ (45)	$ (377)
Agency Commercial MBS [Member]
Available for sale securities, less than 12 months, number of investment positions	33	2
Available for sale securities, less than 12 months, fair value	$ 233,147	$ 6,966
Available for sale securities, less than 12 months, unrealized loss	$ (2,210)	$ (132)
Available for sale securities, 12 months or longer, number of investment positions	0	0
Available for sale securities, 12 months or longer, fair value	$ 0	$ 0
Available for sale securities, 12 months or longer, unrealized loss	$ 0	$ 0
Available for sale securities, total, number of investment positions	33	2
Available for sale securities, total, fair value	$ 233,147	$ 6,966
Available for sale securities, total, unrealized loss	$ (2,210)	$ (132)
Corporate Debt Securities [Member]
Available for sale securities, less than 12 months, number of investment positions	0	0
Held to Maturity securities, less than 12 months, number of investment positions	2	23
Available for sale securities, less than 12 months, fair value	$ 0	$ 0
Held to Maturity securities, less than 12 months, fair value	4,705	251,790
Available for sale securities, less than 12 months, unrealized loss	0	0
Held to Maturity securities, less than 12 months, unrealized loss	$ (9)	$ (4,230)
Available for sale securities, 12 months or longer, number of investment positions	129	138
Held to Maturity securities, 12 months or longer, number of investment positions	27	35
Available for sale securities, 12 months or longer, fair value	$ 1,796,562	$ 1,824,327
Held to Maturity securities, 12 months or longer, fair value	373,660	451,420
Available for sale securities, 12 months or longer, unrealized loss	(119,619)	(195,334)
Held to Maturity securities, 12 months or longer, unrealized loss	$ (9,315)	$ (28,007)
Available for sale securities, total, number of investment positions	129	138
Held to Maturity securities, total, number of investment positions	29	58
Available for sale securities, total, fair value	$ 1,796,562	$ 1,824,327
Held to Maturity securities, total, fair value	378,365	703,210
Available for sale securities, total, unrealized loss	(119,619)	(195,334)
Held to Maturity securities, total, unrealized loss	$ (9,324)	$ (32,237)
US Government Agencies Debt Securities [Member]
Available for sale securities, less than 12 months, number of investment positions	0	3
Available for sale securities, less than 12 months, fair value	$ 0	$ 12,085
Available for sale securities, less than 12 months, unrealized loss	$ 0	$ (53)
Available for sale securities, 12 months or longer, number of investment positions	19	19
Available for sale securities, 12 months or longer, fair value	$ 288,409	$ 275,467
Available for sale securities, 12 months or longer, unrealized loss	$ (7,888)	$ (19,032)
Available for sale securities, total, number of investment positions	19	22
Available for sale securities, total, fair value	$ 288,409	$ 287,552
Available for sale securities, total, unrealized loss	$ (7,888)	$ (19,085)
Collateralized Debt Obligations [Member]
Available for sale securities, less than 12 months, number of investment positions	3	3
Available for sale securities, less than 12 months, fair value	$ 25,645	$ 26,825
Available for sale securities, less than 12 months, unrealized loss	$ (78)	$ (15)
Available for sale securities, 12 months or longer, number of investment positions	9	32
Available for sale securities, 12 months or longer, fair value	$ 84,308	$ 309,249
Available for sale securities, 12 months or longer, unrealized loss	$ (1,405)	$ (5,193)
Available for sale securities, total, number of investment positions	12	35
Available for sale securities, total, fair value	$ 109,953	$ 336,074
Available for sale securities, total, unrealized loss	$ (1,483)	$ (5,208)

X

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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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