Loans and Allowance for Credit Losses - Foregone on Non-accrual Loans and Loans Classified as TDR (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Note 5 - Loans - Summary of Interest Foregone on Non-accrual Loans and Loans Classified as TDR (Details)
Interest income that would have been recognized had the loans performed in accordance with their original terms	$ 2,309	$ 1,691	$ 1,845
Less: Interest income included in the results of operations	746	620	412
Total foregone interest	$ 1,563	$ 1,071	$ 1,433

The gross interest income that would have been recorded in the period on troubled debt restructurings and nonaccrual loans, if the loans had been current in accordance with their original terms and had been outstanding throughout the period or since origination, if held for part of the period.

No definition available.

Name:	ffic_LoansAndLeasesReceivableImpairedTroubledDebtAndNonAccrualLoansInterestIncome
Namespace Prefix:	ffic_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration