Note 3 - Loans and Allowance for Loan Losses - Non-performing Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Loans ninety days or more past due and still accruing		$ 2,424
Non-accrual loans	16,253	15,710
Total non-performing loans	16,253	18,134
Mortgage Receivable [Member]
Non-accrual loans	10,861	14,746
Non-Mortgage Loans [Member]
Non-accrual loans	5,392	964
Commercial Real Estate Portfolio Segment [Member]
Loans ninety days or more past due and still accruing		2,424
Commercial Real Estate Portfolio Segment [Member] \| Mortgage Receivable [Member]
Non-accrual loans	1,379	1,473
Multi-family Residential Portfolio Segment [Member] \| Mortgage Receivable [Member]
Non-accrual loans	2,410	3,598
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member] \| Mortgage Receivable [Member]
Non-accrual loans	928	1,867
One-To-Four Family - Residential Portfolio Segment [Member] \| Mortgage Receivable [Member]
Non-accrual loans	6,144	7,808
Small Business Administration Portfolio Segment [Member] \| Non-Mortgage Loans [Member]
Non-accrual loans	1,267	46
Taxi Medallion Portfolio Segment [Member] \| Non-Mortgage Loans [Member]
Non-accrual loans	613	918
Commercial Business and Other Portfolio Segment [Member] \| Non-Mortgage Loans [Member]
Non-accrual loans	$ 3,512

Total non-accrual loans and loans ninety days or more past due and are still accruing.

No definition available.

Name:	ffic_TotalNonAccrualLoansAndLoansNinetyDaysOrMorePastDueAndStillAccruing
Namespace Prefix:	ffic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_MortgageReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=ffic_NonMortgageLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ffic_MultiFamilyResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ffic_OneToFourFamilyMixedUsePropertyPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ffic_OneToFourFamilyResidentialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ffic_SmallBusinessAdministrationPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ffic_TaxiMedallionPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ffic_CommercialBusinessAndOtherPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: