Note 3 - Loans and Allowance for Loan Losses - Age Analysis of Recorded Investment in Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Past due	$ 36,823	$ 53,062
Current	4,782,311	4,319,549
Loans	4,819,134	4,372,611
Multi-family Residential Portfolio Segment [Member]
Past due	4,699	14,019
Current	2,173,805	2,041,209
Loans	2,178,504	2,055,228
Commercial Real Estate Portfolio Segment [Member]
Past due	4,533	6,553
Current	1,241,599	994,683
Loans	1,246,132	1,001,236
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Past due	9,844	16,451
Current	548,658	556,592
Loans	558,502	573,043
One-To-Four Family - Residential Portfolio Segment [Member]
Past due	12,072	14,549
Current	173,695	173,289
Loans	185,767	187,838
Co-Operative Apartments Portfolio Segment [Member]
Past due	0	0
Current	7,418	8,285
Loans	7,418	8,285
Construction Portfolio Segment [Member]
Past due	0	1,000
Current	11,495	6,284
Loans	11,495	7,284
Small Business Administration Portfolio Segment [Member]
Past due	1,827	260
Current	13,371	11,934
Loans	15,198	12,194
Taxi Medallion Portfolio Segment [Member]
Past due	3,825	0
Current	15,171	20,881
Loans	18,996	20,881
Commercial Business and Other [Member]
Past due	23
Current	597,099
Loans	597,122	506,622
Commercial Business and Other Portfolio Segment [Member]
Past due		230
Current		506,392
Loans	597,122	506,622
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	14,475	25,174
Financing Receivables, 30 to 59 Days Past Due [Member] | Multi-family Residential Portfolio Segment [Member]
Past due	2,575	9,421
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Past due	3,363	2,820
Financing Receivables, 30 to 59 Days Past Due [Member] | One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Past due	4,671	8,630
Financing Receivables, 30 to 59 Days Past Due [Member] | One-To-Four Family - Residential Portfolio Segment [Member]
Past due	3,831	4,261
Financing Receivables, 30 to 59 Days Past Due [Member] | Co-Operative Apartments Portfolio Segment [Member]
Past due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction Portfolio Segment [Member]
Past due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Small Business Administration Portfolio Segment [Member]
Past due	13	42
Financing Receivables, 30 to 59 Days Past Due [Member] | Taxi Medallion Portfolio Segment [Member]
Past due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Business and Other [Member]
Past due	22
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Business and Other Portfolio Segment [Member]
Past due		0
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	1,266	2,371
Financing Receivables, 60 to 89 Days Past Due [Member] | Multi-family Residential Portfolio Segment [Member]
Past due	287	804
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Past due	22	153
Financing Receivables, 60 to 89 Days Past Due [Member] | One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Past due	762	1,258
Financing Receivables, 60 to 89 Days Past Due [Member] | One-To-Four Family - Residential Portfolio Segment [Member]
Past due	194	154
Financing Receivables, 60 to 89 Days Past Due [Member] | Co-Operative Apartments Portfolio Segment [Member]
Past due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction Portfolio Segment [Member]
Past due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Small Business Administration Portfolio Segment [Member]
Past due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Taxi Medallion Portfolio Segment [Member]
Past due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Business and Other [Member]
Past due	1
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Business and Other Portfolio Segment [Member]
Past due		2
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	21,082	25,517
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Multi-family Residential Portfolio Segment [Member]
Past due	1,837	3,794
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Past due	1,148	3,580
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Past due	4,411	6,563
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | One-To-Four Family - Residential Portfolio Segment [Member]
Past due	8,047	10,134
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Co-Operative Apartments Portfolio Segment [Member]
Past due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction Portfolio Segment [Member]
Past due	0	1,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Small Business Administration Portfolio Segment [Member]
Past due	1,814	218
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Taxi Medallion Portfolio Segment [Member]
Past due	3,825	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Business and Other [Member]
Past due	$ 0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Business and Other Portfolio Segment [Member]
Past due		$ 228