Note 9 - Fair Value Measurements - Fair Value Estimates for Financial Instruments, Excluding Financial Instruments on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Financial Liabilities:
Bank Term Funding Program borrowings	$ 200,000		$ 0
Reported Value Measurement [Member]
Cash and due from banks		$ 486,124	190,314
Debt securities held to maturity		860,868	878,396
Loans		815,890	849,735
Financial Liabilities:
Deposits		5,131,440	5,474,267
Bank Term Funding Program borrowings		200,000
Securities sold under repurchase agreements		100,167	58,162
Estimate of Fair Value Measurement [Member]
Cash and due from banks		486,124	190,314
Debt securities held to maturity		817,071	849,562
Loans		813,272	847,031
Financial Liabilities:
Deposits		5,129,495	5,474,012
Bank Term Funding Program borrowings		200,112
Securities sold under repurchase agreements		100,167	58,162
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and due from banks		486,124	190,314
Debt securities held to maturity		0	0
Loans		0	0
Financial Liabilities:
Deposits		0	0
Bank Term Funding Program borrowings		0
Securities sold under repurchase agreements		0	0
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and due from banks		0	0
Debt securities held to maturity		817,071	849,562
Loans		0	0
Financial Liabilities:
Deposits		5,042,434	5,377,465
Bank Term Funding Program borrowings		200,112
Securities sold under repurchase agreements		100,167	58,162
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and due from banks		0	0
Debt securities held to maturity		0	0
Loans		813,272	847,031
Financial Liabilities:
Deposits		87,061	96,547
Bank Term Funding Program borrowings		$ 0
Securities sold under repurchase agreements			$ 0