Note 2 - Investment Securities - Available-for-sale Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Securities available-for-sale, amortized cost	$ 1,112,166	$ 1,114,961
Securities available-for-sale, unrealized gains	151	144
Securities available-for-sale, unrealized losses	(98,455)	(124,991)
Securities available-for-sale, fair value	1,013,862	990,114
US Treasury Securities and US Government Agencies Debt Securities [Member]
Securities available-for-sale, amortized cost	248,012	198,182
Securities available-for-sale, unrealized gains	0	33
Securities available-for-sale, unrealized losses	(8)	0
Securities available-for-sale, fair value	248,004	198,215
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale, amortized cost	82,169	88,895
Securities available-for-sale, unrealized gains	119	110
Securities available-for-sale, unrealized losses	(3,240)	(4,847)
Securities available-for-sale, fair value	79,048	84,158
Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member]
Securities available-for-sale, amortized cost	655,139	696,767
Securities available-for-sale, unrealized gains	29	0
Securities available-for-sale, unrealized losses	(82,977)	(105,790)
Securities available-for-sale, fair value	572,191	590,977
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, amortized cost	125,223	128,431
Securities available-for-sale, unrealized gains	3	1
Securities available-for-sale, unrealized losses	(12,172)	(14,198)
Securities available-for-sale, fair value	113,054	114,234
Other Debt Obligations [Member]
Securities available-for-sale, amortized cost	1,623	2,686
Securities available-for-sale, unrealized gains	0	0
Securities available-for-sale, unrealized losses	(58)	(156)
Securities available-for-sale, fair value	$ 1,565	$ 2,530