Note 5 - Loans - Age Analysis of Recorded Investment in Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans, past due	$ 22,056	$ 28,815
Loans, current	5,342,780	5,131,421
Total Loans	5,364,836	5,160,236
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	6,984	7,706
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due	3,139	4,124
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	11,933	16,985
Multi-family Residential Portfolio Segment [Member]
Loans, past due	4,582	6,410
Loans, current	2,230,788	2,267,185
Total Loans	2,235,370	2,273,595
Multi-family Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	3,233	2,533
Multi-family Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due	486	279
Multi-family Residential Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	863	3,598
Commercial Real Estate Portfolio Segment [Member]
Loans, past due	4,096	7,774
Loans, current	1,456,459	1,360,338
Total Loans	1,460,555	1,368,112
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	562	1,680
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due	2,025	2,197
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	1,509	3,897
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Loans, past due	2,815	4,297
Loans, current	562,487	559,909
Total Loans	565,302	564,206
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	1,657	1,570
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due	362	860
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	796	1,867
One-To-Four Family - Residential Portfolio Segment [Member]
Loans, past due	8,258	10,224
Loans, current	180,717	170,439
Total Loans	188,975	180,663
One-To-Four Family - Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	1,382	1,921
One-To-Four Family - Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due	266	680
One-To-Four Family - Residential Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	6,610	7,623
Co-Operative Apartments Portfolio Segment [Member]
Loans, past due
Loans, current	7,771	6,895
Total Loans	7,771	6,895
Co-Operative Apartments Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due
Co-Operative Apartments Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due
Co-Operative Apartments Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due
Construction Portfolio Segment [Member]
Loans, past due
Loans, current	40,239	8,479
Total Loans	40,239	8,479
Construction Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due
Construction Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due
Construction Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due
Small Business Administration Portfolio Segment [Member]
Loans, past due	1,540
Loans, current	12,782	18,479
Total Loans	14,322	18,479
Small Business Administration Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	145
Small Business Administration Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due
Small Business Administration Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	1,395
Taxi Medallion Portfolio Segment [Member]
Loans, past due		108
Loans, current	6,078	6,726
Total Loans	6,078	6,834
Taxi Medallion Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due
Taxi Medallion Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due		108
Taxi Medallion Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due
Commercial Business and Other Portfolio Segment [Member]
Loans, past due	765	2
Loans, current	845,459	732,971
Total Loans	846,224	732,973
Commercial Business and Other Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans, past due	5	2
Commercial Business and Other Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans, past due
Commercial Business and Other Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans, past due	$ 760