Note 7 - Loans and the Allowance for Credit Losses - Composition of Loan Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	$ 11,435,643	$ 11,457,558
Net deferred loan fees	(3,110)	(4,278)
Total loans receivable	11,432,533	11,453,280
Commercial Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	1,656,916	1,565,963
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	7,981,622	8,054,696
Commercial Construction Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	585,707	623,902
Residential Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	1,207,092	1,210,980
Consumer Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Fee, and Loan in Process	$ 4,306	$ 2,017