Note 5 - Loans - Activity in the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Beginning balance	$ 20,220	$ 22,157	$ 20,351	$ 22,229
Charge-off's	(220)	(324)	(721)	(853)
Recoveries	309	170	526	627
Provision (Benefit)		3,266	153	3,266
Ending balance	20,309	25,269	20,309	25,269
Multi-family Residential Portfolio Segment [Member]
Beginning balance	5,538	5,917	5,823	5,923
Charge-off's	(18)	(290)	(99)	(452)
Recoveries		66	2	297
Provision (Benefit)	37	43	(169)	(32)
Ending balance	5,557	5,736	5,557	5,736
Commercial Real Estate Portfolio Segment [Member]
Beginning balance	4,726	4,688	4,643	4,487
Charge-off's				(4)
Recoveries		25		93
Provision (Benefit)	(650)	(86)	(567)	51
Ending balance	4,076	4,627	4,076	4,627
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Beginning balance	2,297	2,568	2,545	2,903
Charge-off's	(3)	(1)	(3)	(36)
Recoveries	39		118	68
Provision (Benefit)	(407)	(49)	(734)	(417)
Ending balance	1,926	2,518	1,926	2,518
One-To-Four Family - Residential Portfolio Segment [Member]
Beginning balance	1,003	990	1,082	1,015
Charge-off's			(1)	(170)
Recoveries	258	58	370	58
Provision (Benefit)	(382)	(90)	(572)	55
Ending balance	879	958	879	958
Construction Portfolio Segment [Member]
Beginning balance	264	130	68	92
Charge-off's	0	0
Recoveries	0	0
Provision (Benefit)	(2)	(13)	194	25
Ending balance	262	117	262	117
Small Business Administration Portfolio Segment [Member]
Beginning balance	549	306	669	481
Charge-off's	(144)		(196)	(89)
Recoveries	10	17	25	66
Provision (Benefit)	138	70	55	(65)
Ending balance	553	393	553	393
Taxi Medallion Portfolio Segment [Member]
Beginning balance		2,330		2,243
Charge-off's	(40)		(393)	(54)
Recoveries
Provision (Benefit)	40	3,661	393	3,802
Ending balance		5,991		5,991
Commercial Business and Other Portfolio Segment [Member]
Beginning balance	5,832	4,668	5,521	4,492
Charge-off's	(15)	(33)	(29)	(48)
Recoveries	2	4	11	45
Provision (Benefit)	1,186	290	1,502	440
Ending balance	7,005	4,929	7,005	4,929
Unallocated Financing Receivables [Member]
Beginning balance	11	560		593
Charge-off's
Recoveries
Provision (Benefit)	40	(560)	51	(593)
Ending balance	$ 51		$ 51

A valuation allowance for financing receivables that are expected to be uncollectible.

Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of recovery of financing receivables doubtful of collection that were previously charged off.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of direct write-downs of financing receivables charged against the allowance.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

+ Details

Name:	us-gaap_ProvisionForLoanLeaseAndOtherLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=ffic_MultiFamilyResidentialPortfolioSegmentMember
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_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_ConstructionPortfolioSegmentMember
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:

- Details

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