Note 5 - Loans - Loans Evaluated for Impairment (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Financing receivables, ending balance	$ 5,623,135,000	$ 5,536,296,000
Financing receivables, individually evaluated for impairment	22,491,000	25,519,000
Financing receivables, collectively evaluated for impairment	5,600,644,000	5,510,777,000
Ending balance: individually evaluated for impairment	372,000	1,160,000
Ending balance: collectively evaluated for impairment	21,138,000	19,785,000
Multi-family Residential Portfolio Segment [Member]
Financing receivables, ending balance	2,263,875,000	2,269,048,000
Financing receivables, individually evaluated for impairment	4,119,000	4,500,000
Financing receivables, collectively evaluated for impairment	2,259,756,000	2,264,548,000
Ending balance: individually evaluated for impairment	96,000	100,000
Ending balance: collectively evaluated for impairment	5,410,000	5,576,000
Commercial Real Estate Portfolio Segment [Member]
Financing receivables, ending balance	1,524,693,000	1,542,547,000
Financing receivables, individually evaluated for impairment	1,555,000	1,435,000
Financing receivables, collectively evaluated for impairment	1,523,138,000	1,541,112,000
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	4,265,000	4,315,000
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Financing receivables, ending balance	582,264,000	577,741,000
Financing receivables, individually evaluated for impairment	3,430,000	3,098,000
Financing receivables, collectively evaluated for impairment	578,834,000	574,643,000
Ending balance: individually evaluated for impairment	49,000	143,000
Ending balance: collectively evaluated for impairment	1,737,000	1,724,000
One-To-Four Family - Residential Portfolio Segment [Member]
Financing receivables, ending balance	184,024,000	190,350,000
Financing receivables, individually evaluated for impairment	6,150,000	6,889,000
Financing receivables, collectively evaluated for impairment	177,874,000	183,461,000
Ending balance: individually evaluated for impairment	49,000	51,000
Ending balance: collectively evaluated for impairment	697,000	698,000
Co-Operative Apartments Portfolio Segment [Member]
Financing receivables, ending balance	8,137,000	8,498,000
Financing receivables, individually evaluated for impairment	0	0
Financing receivables, collectively evaluated for impairment	8,137,000	8,498,000
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	0	0
Construction Portfolio Segment [Member]
Financing receivables, ending balance	58,503,000	50,600,000
Financing receivables, individually evaluated for impairment	0	0
Financing receivables, collectively evaluated for impairment	58,503,000	50,600,000
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	381,000	329,000
Small Business Administration Portfolio Segment [Member]
Financing receivables, ending balance	14,511,000	15,210,000
Financing receivables, individually evaluated for impairment	1,224,000	1,267,000
Financing receivables, collectively evaluated for impairment	13,287,000	13,943,000
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	382,000	418,000
Taxi Medallion Portfolio Segment [Member]
Financing receivables, ending balance	3,555,000	4,539,000
Financing receivables, individually evaluated for impairment	3,555,000	4,539,000
Financing receivables, collectively evaluated for impairment	0	0
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	0	0
Commercial Business and Other Portfolio Segment [Member]
Financing receivables, ending balance	983,573,000	877,763,000
Financing receivables, individually evaluated for impairment	2,458,000	3,791,000
Financing receivables, collectively evaluated for impairment	981,115,000	873,972,000
Ending balance: individually evaluated for impairment	178,000	866,000
Ending balance: collectively evaluated for impairment	$ 8,266,000	$ 6,725,000

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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 (g)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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