Note 12 - Fair Value Measurements and Fair Value of Financial Instruments - Financial Assets and Liabilities Measured on a Non-recurring Basis (Details) - USD ($) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Total at Fair Value		$ 1,740,019		$ 1,699,623
Total Losses		1,289	$ 6,783	4,296	$ 4,145
Fair Value, Nonrecurring [Member]
Total at Fair Value		40,670		27,756
Fair Value, Inputs, Level 1 [Member]
Total at Fair Value		573,178		535,706
Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Fair Value, Inputs, Level 2 [Member]
Total at Fair Value		1,166,841		1,163,917
Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Fair Value, Inputs, Level 3 [Member]
Total at Fair Value		0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		40,670		27,756
Impaired Loans [Member]
Total Losses		1,289	6,783	4,069	3,877
Impaired Loans [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		20,131		7,073
Impaired Loans [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Impaired Loans [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		20,131		7,073
Impaired Loans [Member] | Commercial Portfolio Segment [Member]
Total Losses		1,038	2,793	0	1,786
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		129		191
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Impaired Loans [Member] | Commercial Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		129		191
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member]
Total Losses		251	3,990	4,069	2,091
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		20,002		6,882
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		20,002		6,882
Other Real Estate Owned [Member]
Total Losses	[1]	0	0	0	0
Other Real Estate Owned [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value	[1]	20,446		20,446
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value	[1]	0		0
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value	[1]	0		0
Other Real Estate Owned [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value	[1]	20,446		20,446
Investments in Venture Capital [Member]
Total Losses		0	$ 0	227	$ 268
Investments in Venture Capital [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		93		237
Investments in Venture Capital [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Investments in Venture Capital [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		0		0
Investments in Venture Capital [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Nonrecurring [Member]
Total at Fair Value		$ 93		$ 237

[1] Other real estate owned balance of $19.4 million in the Consolidated Balance Sheets is net of estimated disposal costs.