Note 8 - Derivatives and Hedging Activities - Cash flow hedging and fair value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest And Dividend Income | Unhedged Derivatives
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Income and expense line items presented in the consolidated statements of income	$ 413,410	$ 292,571	$ 200,155
Interest Expense | Unhedged Derivatives
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Income and expense line items presented in the consolidated statements of income	192,404	61,451	21,922
Gain on interest rate caps on deposits | Interest Expense | Unhedged Derivatives
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Gain Loss From Components Excluded From Assessment Of Cash Flow Hedge Effectiveness Net	(7,639)	(1,422)	697
Interest Rate Swaps on Variable Rate Loans | Interest And Dividend Income | Unhedged Derivatives
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Gain Loss From Components Excluded From Assessment Of Cash Flow Hedge Effectiveness Net	(10,763)	(829)	1,006
Gain on interest rate swaps on fixed rate loans | Interest And Dividend Income
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Gain Loss From Components Excluded From Assessment Of Cash Flow Hedge Effectiveness Net	1,746
Gain on interest rate swaps on junior subordinated debentures | Interest Expense
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net [Abstract]
Income and expense line items presented in the consolidated statements of income	$ (1,167)	$ 500	$ 1,116