Note 3 - Debt and Equity Securities (Details Textual) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale, Amortized Cost	$ 936,998,000	$ 972,315,000
Debt Securities, Available-for-Sale	799,841,000	822,812,000
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	137,189,000	149,504,000
Debt Securities, Available-for-Sale, Unrealized Loss Position	794,332,000	822,246,000
Asset Pledged as Collateral [Member] | Public Deposits and Other Required Purposes [Member]
Debt Securities, Available-for-Sale, Amortized Cost	502,138,000	477,051,000
Debt Securities, Available-for-Sale	429,123,000	405,403,000
Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-Sale, Amortized Cost	139,838,000	148,460,000
Debt Securities, Available-for-Sale	118,049,000	126,190,000
US Government Sponsored Entities and Agencies [Member]
Debt Securities, Available-for-Sale	9,500,000
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	$ 1,600,000
Percent of Mortgage Backed Securties	98.00%
Asset-Backed Securities [Member]
Debt Securities, Available-for-Sale, Amortized Cost	$ 45,048,000	47,538,000
Debt Securities, Available-for-Sale	42,886,000	45,250,000
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	2,192,000	2,288,000
Debt Securities, Available-for-Sale, Unrealized Loss Position	37,891,000	45,250,000
Corporate Debt Securities [Member]
Debt Securities, Available-for-Sale, Amortized Cost	2,500,000	2,500,000
Debt Securities, Available-for-Sale	2,381,000	2,403,000
Debt Securities, Available-for-Sale, Unrealized Loss Position, Accumulated Loss	119,000	97,000
Debt Securities, Available-for-Sale, Unrealized Loss Position	$ 2,381,000	$ 2,403,000