Note 5 - Loans - Troubled Debt Restructurings That Are Performing According to Their Restructured Terms (Details) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017	Dec. 31, 2017 USD ($)
Financing Receivable, Modifications, Number of Contracts	0	0	5
Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		38		41
Recorded investment	$ 10,609	$ 10,609		$ 13,207
Multi-Family Residential [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		9		9
Recorded investment	2,488	$ 2,488		$ 2,518
Commercial Real Estate Loans [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts				2
Recorded investment				$ 1,986
One-To-Four Family - Mixed Used Property [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		5		5
Recorded investment	1,726	$ 1,726		$ 1,753
One-To-Four Family - Residential [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		3		3
Recorded investment	562	$ 562		$ 572
Taxi Medallion Portfolio Segment [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		19		20
Recorded investment	5,482	$ 5,482		$ 5,916
Commercial Business and Other [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		2		2
Recorded investment	$ 351	$ 351		$ 462