Note 3 - Investment Securities - Available-for-sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Securities available-for-sale, amortized cost	$ 1,114,961	$ 1,154,153
Securities available-for-sale, unrealized gains	144	245
Securities available-for-sale, unrealized losses	(124,991)	(123,219)
Securities available-for-sale, fair value	990,114	1,031,179
US Treasury Securities and US Government Agencies Debt Securities [Member]
Securities available-for-sale, amortized cost	198,182	119,931
Securities available-for-sale, unrealized gains	33	0
Securities available-for-sale, unrealized losses	0	(3,662)
Securities available-for-sale, fair value	198,215	116,269
US Government-sponsored Enterprises Debt Securities [Member]
Securities available-for-sale, amortized cost	88,895	104,677
Securities available-for-sale, unrealized gains	110	157
Securities available-for-sale, unrealized losses	(4,847)	(4,987)
Securities available-for-sale, fair value	84,158	99,847
Mortgage-Backed Security, Issued by US Government-Sponsored Enterprise [Member]
Securities available-for-sale, amortized cost	696,767	789,145
Securities available-for-sale, unrealized gains	0	83
Securities available-for-sale, unrealized losses	(105,790)	(101,189)
Securities available-for-sale, fair value	590,977	688,039
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, amortized cost	128,431	136,579
Securities available-for-sale, unrealized gains	1	5
Securities available-for-sale, unrealized losses	(14,198)	(13,094)
Securities available-for-sale, fair value	114,234	123,490
Other Debt Obligations [Member]
Securities available-for-sale, amortized cost	2,686	3,821
Securities available-for-sale, unrealized gains	0	0
Securities available-for-sale, unrealized losses	(156)	(287)
Securities available-for-sale, fair value	$ 2,530	$ 3,534