Loans - Foregone on Non-accrual Loans and Loans Classified as TDR (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Loans
Interest income that would have been recognized had the loans performed in accordance with their original terms	$ 900	$ 425	$ 2,246	$ 1,405
Less: Interest income included in the results of operations	(5)	(2)	(10)	(20)
Total foregone interest	$ 895	$ 423	$ 2,236	$ 1,385

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