Note 5 - Loans - Age Analysis of Recorded Investment in Loans (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Loans, past due	$ 25,745,000	$ 22,997,000
Loans, current	5,597,390,000	5,513,299,000
Total Loans	5,623,135,000	5,536,296,000
Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	9,990,000	6,913,000
Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	926,000	1,740,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	14,829,000	14,344,000
Multi-family Residential Portfolio Segment [Member]
Loans, past due	3,820,000	4,636,000
Loans, current	2,260,055,000	2,264,412,000
Total Loans	2,263,875,000	2,269,048,000
Multi-family Residential Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	1,466,000	1,887,000
Multi-family Residential Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	346,000	339,000
Multi-family Residential Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	2,008,000	2,410,000
Commercial Real Estate Portfolio Segment [Member]
Loans, past due	4,829,000	1,758,000
Loans, current	1,519,864,000	1,540,789,000
Total Loans	1,524,693,000	1,542,547,000
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	3,341,000	379,000
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	0	0
Commercial Real Estate Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	1,488,000	1,379,000
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Loans, past due	2,532,000	2,253,000
Loans, current	579,732,000	575,488,000
Total Loans	582,264,000	577,741,000
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	986,000	1,003,000
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	72,000	322,000
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	1,474,000	928,000
One-To-Four Family - Residential Portfolio Segment [Member]
Loans, past due	6,864,000	7,708,000
Loans, current	177,160,000	182,642,000
Total Loans	184,024,000	190,350,000
One-To-Four Family - Residential Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	945,000	1,564,000
One-To-Four Family - Residential Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	508,000	0
One-To-Four Family - Residential Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	5,411,000	6,144,000
Co-Operative Apartments Portfolio Segment [Member]
Loans, past due	0	0
Loans, current	8,137,000	8,498,000
Total Loans	8,137,000	8,498,000
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	730,000
Loans, current	58,503,000	49,870,000
Total Loans	58,503,000	50,600,000
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	730,000
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	1,224,000	2,109,000
Loans, current	13,287,000	13,101,000
Total Loans	14,511,000	15,210,000
Small Business Administration Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	0	774,000
Small Business Administration Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	0	68,000
Small Business Administration Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	1,224,000	1,267,000
Taxi Medallion Portfolio Segment [Member]
Loans, past due	766,000	0
Loans, current	2,789,000	4,539,000
Total Loans	3,555,000	4,539,000
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	766,000	0
Commercial Business and Other Portfolio Segment [Member]
Loans, past due	5,710,000	3,803,000
Loans, current	977,863,000	873,960,000
Total Loans	983,573,000	877,763,000
Commercial Business and Other Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Loans, past due	3,252,000	1,306,000
Commercial Business and Other Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Loans, past due	0	281,000
Commercial Business and Other Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Loans, past due	$ 2,458,000	$ 2,216,000