Concentration of Credit Risk (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Note to Financial Statements
Lending Limit to Single Borrower	$ 123.8	$ 137.3
Largest Aggregate Amount of Outstanding Loans to Single Borrower	$ 103.2	$ 109.4

Largest aggregate amount of loans to a single borrower.

No definition available.

Name:	ffic_LargestAggregateAmountOfLoansToSingleBorrower
Namespace Prefix:	ffic_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant