Note 5 - Loans - Age Analysis of Recorded Investment in Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Loans, past due	$ 28,783	$ 22,997
Loans, current	5,721,617	5,513,299
Total Loans	5,750,400	5,536,296
Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	11,386	6,913
Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	3,553	1,740
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	13,844	14,344
Multi-family Residential Portfolio Segment [Member]
Loans, past due	6,090	4,636
Loans, current	2,226,215	2,264,412
Total Loans	2,232,305	2,269,048
Multi-family Residential Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	1,112	1,887
Multi-family Residential Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	1,401	339
Multi-family Residential Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	3,577	2,410
Commercial Real Estate Portfolio Segment [Member]
Loans, past due	7,756	1,758
Loans, current	1,551,825	1,540,789
Total Loans	1,559,581	1,542,547
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	5,944	379
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	940	0
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	872	1,379
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Loans, past due	2,735	2,253
Loans, current	584,365	575,488
Total Loans	587,100	577,741
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	1,458	1,003
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	869	322
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	408	928
One-To-Four Family - Residential Portfolio Segment [Member]
Loans, past due	6,313	7,708
Loans, current	178,119	182,642
Total Loans	184,432	190,350
One-To-Four Family - Residential Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	1,020	1,564
One-To-Four Family - Residential Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	243	0
One-To-Four Family - Residential Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	5,050	6,144
Co-Operative Apartments Portfolio Segment [Member]
Loans, past due	0	0
Loans, current	9,089	8,498
Total Loans	9,089	8,498
Co-Operative Apartments Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	0	0
Co-Operative Apartments Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	0	0
Co-Operative Apartments Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	0	0
Construction Portfolio Segment [Member]
Loans, past due	0	730
Loans, current	64,234	49,870
Total Loans	64,234	50,600
Construction Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	0	0
Construction Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	0	730
Construction Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	0	0
Small Business Administration Portfolio Segment [Member]
Loans, past due	3,000	2,109
Loans, current	10,982	13,101
Total Loans	13,982	15,210
Small Business Administration Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	1,849	774
Small Business Administration Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	0	68
Small Business Administration Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	1,151	1,267
Taxi Medallion Portfolio Segment [Member]
Loans, past due	766	0
Loans, current	2,747	4,539
Total Loans	3,513	4,539
Taxi Medallion Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	0	0
Taxi Medallion Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	0	0
Taxi Medallion Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	766	0
Commercial Business and Other Portfolio Segment [Member]
Loans, past due	2,123	3,803
Loans, current	1,094,041	873,960
Total Loans	1,096,164	877,763
Commercial Business and Other Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	3	1,306
Commercial Business and Other Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	100	281
Commercial Business and Other Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	$ 2,020	$ 2,216