Note 4 - Loans and the Allowance for Credit Losses (Details Textual) Pure in Thousands			12 Months Ended
		Jan. 01, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Financing Receivable, before Allowance for Credit Loss, Fee and Loan in Process			$ 8,109,161,000	$ 6,838,351,000
Financing Receivable, after Allowance for Credit Loss, Total			8,009,176,000	6,749,849,000
Allowance for Loan Losses Included in Unallocated		$ 6,600,000
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend			0
Financing Receivable, Troubled Debt Restructuring			75,100,000	79,500,000
Financing Receivable, Allowance for Credit Loss, Ending Balance			$ 90,513,000	$ 78,773,000	$ 79,226,000	$ 38,293,000
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts			0	0	0
Troubled Debt Restructurings [Member]
Financing Receivable, Allowance for Credit Loss, Ending Balance			$ 4,200,000	$ 10,400,000
Taxi Medallion Loans [Member]
Financing Receivable, Troubled Debt Restructuring			300,000
Nonperforming Financial Instruments [Member]
Financing Receivable, Troubled Debt Restructuring			23,700,000	35,900,000
Performing Financial Instruments [Member]
Financing Receivable, Troubled Debt Restructuring			51,400,000	43,600,000
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member]
Financing Receivable, after Allowance for Credit Loss, Total			2,700,000,000	2,500,000,000
Commercial Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Fee and Loan in Process	[1]		1,472,734,000	1,299,428,000
Financing Receivable, Allowance for Credit Loss, Ending Balance			28,903,000	25,969,000	$ 28,443,000	8,349,000
Commercial Portfolio Segment [Member] | Paycheck Protection Program CARES Act [Member]
Financing Receivable, before Allowance for Credit Loss, Fee and Loan in Process			11,400,000	93,100,000
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss, Fee and Loan in Process			5,795,228,000	4,741,590,000
Financing Receivable, Allowance for Credit Loss, Ending Balance			53,742,000	$ 45,589,000	$ 39,330,000	$ 20,853,000
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Financing Receivable, Troubled Debt Restructuring, One Time Principal Payment			$ 500,000

[1] Included in commercial loans as of December 31, 2022 and December 31, 2021 were Paycheck Protection Program (“PPP”) loans of $11.4 million and $93.1 million, respectively. These loans are 100% federally guaranteed and currently not subject to any allocation of allowance for credit losses.