Note 5 - Loans and the Allowance for Credit Losses - Analysis of Aging of Loans (Details) - USD ($) $ in Thousands		Sep. 30, 2022	Dec. 31, 2021
Loans and Leases Receivable, Gross		$ 7,910,013	$ 6,838,351
Nonaccrual		57,447	61,700
Financial Asset, 30 to 59 Days Past Due [Member]
Loans and Leases Receivable, Gross		842	7,364
Financial Asset, 60 to 89 Days Past Due [Member]
Loans and Leases Receivable, Gross		13	2,030
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans and Leases Receivable, Gross		10,068	13,531
Financial Asset, Past Due [Member]
Loans and Leases Receivable, Gross		68,370	84,625
Financial Asset, Not Past Due [Member]
Loans and Leases Receivable, Gross		7,841,643	6,753,726
Commercial Portfolio Segment [Member]
Loans and Leases Receivable, Gross	[1]	1,448,727	1,299,428
Nonaccrual		26,858	30,062
Commercial Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans and Leases Receivable, Gross		171	4,305
Commercial Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans and Leases Receivable, Gross		13	729
Commercial Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans and Leases Receivable, Gross		4,392	4,457
Commercial Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Loans and Leases Receivable, Gross		31,434	39,553
Commercial Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans and Leases Receivable, Gross		1,417,293	1,259,875
Commercial Real Estate Portfolio Segment [Member]
Loans and Leases Receivable, Gross		5,666,848	4,741,590
Nonaccrual		28,138	25,393
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	1,622
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	1,009
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans and Leases Receivable, Gross		5,676	5,935
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Loans and Leases Receivable, Gross		33,814	33,959
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans and Leases Receivable, Gross		5,633,034	4,707,631
Commercial Construction Portfolio Segment [Member]
Loans and Leases Receivable, Gross		537,323	540,178
Nonaccrual		0	3,150
Commercial Construction Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	0
Commercial Construction Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	0
Commercial Construction Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	0
Commercial Construction Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Loans and Leases Receivable, Gross		0	3,150
Commercial Construction Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans and Leases Receivable, Gross		537,323	537,028
Residential Portfolio Segment [Member]
Loans and Leases Receivable, Gross		256,085	255,269
Nonaccrual		2,451	3,095
Residential Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans and Leases Receivable, Gross		671	1,437
Residential Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	292
Residential Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	3,139
Residential Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Loans and Leases Receivable, Gross		3,122	7,963
Residential Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans and Leases Receivable, Gross		252,963	247,306
Consumer Portfolio Segment [Member]
Loans and Leases Receivable, Gross		1,030	1,886
Nonaccrual		0	0
Consumer Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	0
Consumer Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	0
Consumer Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans and Leases Receivable, Gross		0	0
Consumer Portfolio Segment [Member] | Financial Asset, Past Due [Member]
Loans and Leases Receivable, Gross		0	0
Consumer Portfolio Segment [Member] | Financial Asset, Not Past Due [Member]
Loans and Leases Receivable, Gross		$ 1,030	$ 1,886

[1] Includes PPP loans of $11.5 million and $93.1 million as of September 30, 2022 and December 31, 2021 , respectively.