Note 3 - Loans and Allowance for Loan Losses (Details Textual) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Impaired Financing Receivable, Guaranteed by Small Business Administration	$ 0.1	$ 1.5
Servicing Mortgage Loans [Member]
Servicing Asset, Loans Serviced, Amount	38.8
Servicing SBA Loans [Member]
Servicing Asset, Loans Serviced, Amount	$ 14.9
Multi-family Residential Property and Commercial Real Estate and Commerical Business and Other Loans [Member]
Loan Origination, Underwriting Requirements, Minimum Debt Service Coverage	125.00%
Loan Origination, Value, Maximum Percentage	75.00%
Multi-family Residential Property and Commercial Real Estate and Commerical Business and Other Loans [Member] \| Gross Loans [Member] \| Credit Concentration Risk [Member]
Concentration Risk, Percentage	84.80%	83.50%

The portion of recorded impaired financing receivable that has been guaranteed by the Small Business Administration.

No definition available.

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

- Definition

The minimum debt service coverage percentage required to meet the company's underwriting requirements for loan origination.

+ References

No definition available.

+ Details

Name:	ffic_LoanOriginationUnderwritingRequirementsMinimumDebtServiceCoverage
Namespace Prefix:	ffic_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The maximum percentage of appraised value or purchase price of property of which the company will originate loans.

+ References

No definition available.

+ Details

Name:	ffic_LoanOriginationValueMaximumPercentage
Namespace Prefix:	ffic_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate amount of loans serviced for others as part of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method.

+ References

No definition available.

+ Details

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

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13537-108611

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancialInstrumentAxis=ffic_ServicingMortgageLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=ffic_ServicingSBALoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=ffic_GrossLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CreditConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: