Note 5 - Loans - Age Analysis of Recorded Investment in Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Past due	$ 31,481	$ 36,823
Current	5,021,970	4,782,311
Total Loans	5,053,451	4,819,134
Multi-family Residential Portfolio Segment [Member]
Past due	7,994	4,699
Current	2,228,179	2,173,805
Total Loans	2,236,173	2,178,504
Commercial Real Estate Portfolio Segment [Member]
Past due	5,121	4,533
Current	1,347,654	1,241,599
Total Loans	1,352,775	1,246,132
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Past due	6,035	9,844
Current	550,688	548,658
Total Loans	556,723	558,502
One-To-Four Family - Residential Portfolio Segment [Member]
Past due	10,935	12,072
Current	166,643	173,695
Total Loans	177,578	185,767
Co-Operative Apartments Portfolio Segment [Member]
Past due	0	0
Current	7,035	7,418
Total Loans	7,035	7,418
Construction Portfolio Segment [Member]
Past due		0
Current	15,811	11,495
Total Loans	15,811	11,495
Small Business Administration Portfolio Segment [Member]
Past due	245	1,827
Current	14,240	13,371
Total Loans	14,485	15,198
Taxi Medallion Portfolio Segment [Member]
Past due	1,147	3,825
Current	17,018	15,171
Total Loans	18,165	18,996
Commercial Business and Other [Member]
Past due	4
Current	674,702
Total Loans	674,706
Commercial Business and Other Portfolio Segment [Member]
Past due		23
Current		597,099
Total Loans	674,706	597,122
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	16,793	14,475
Financing Receivables, 30 to 59 Days Past Due [Member] | Multi-family Residential Portfolio Segment [Member]
Past due	6,115	2,575
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Past due	3,455	3,363
Financing Receivables, 30 to 59 Days Past Due [Member] | One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Past due	3,577	4,671
Financing Receivables, 30 to 59 Days Past Due [Member] | One-To-Four Family - Residential Portfolio Segment [Member]
Past due	3,646	3,831
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
Financing Receivables, 30 to 59 Days Past Due [Member] | Taxi Medallion Portfolio Segment [Member]
Past due		0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Business and Other [Member]
Past due
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Business and Other Portfolio Segment [Member]
Past due		22
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	1,036	1,266
Financing Receivables, 60 to 89 Days Past Due [Member] | Multi-family Residential Portfolio Segment [Member]
Past due	155	287
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Past due	481	22
Financing Receivables, 60 to 89 Days Past Due [Member] | One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Past due	112	762
Financing Receivables, 60 to 89 Days Past Due [Member] | One-To-Four Family - Residential Portfolio Segment [Member]
Past due	43	194
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
Financing Receivables, 60 to 89 Days Past Due [Member] | Small Business Administration Portfolio Segment [Member]
Past due	245	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
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Business and Other Portfolio Segment [Member]
Past due		1
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	13,652	21,082
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Multi-family Residential Portfolio Segment [Member]
Past due	1,724	1,837
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Past due	1,185	1,148
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Past due	2,346	4,411
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | One-To-Four Family - Residential Portfolio Segment [Member]
Past due	7,246	8,047
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
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Small Business Administration Portfolio Segment [Member]
Past due		1,814
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Taxi Medallion Portfolio Segment [Member]
Past due	1,147	3,825
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Business and Other [Member]
Past due	$ 4
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Business and Other Portfolio Segment [Member]
Past due