Note 7 - Derivatives and Hedging Activities - Cash flow hedging and fair value (Details) - Non Designated - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest And Dividend Income
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	$ 200,155	$ 198,373	$ 216,076
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	21,922	31,423	60,517
Interest Rate Caps On Deposits | Interest Expense
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	697	551
Interest Rate Swaps on Variable 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	1,006
Interest Rate Swaps on Variable Rate Loans | Interest Expense
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		185
Interest rate swaps on TRUPS | Interest Expense
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	$ 1,114	$ 832	$ 215