Note 5 - Loans - Troubled Debt Restructurings That Are Performing According to Their Restructured Terms (Details) $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2019 USD ($)	Mar. 31, 2018	Dec. 31, 2018 USD ($)
Financing Receivable, Modifications, Number of Contracts		0	0
Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		25		31
Recorded investment		$ 6,645		$ 8,365
Multi-Family Residential [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		7		7
Recorded investment		$ 1,906		$ 1,916
One-To-Four Family - Mixed Used Property [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		5		5
Recorded investment		$ 1,674		$ 1,692
One-To-Four Family - Residential [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts		3		3
Recorded investment		$ 547		$ 552
Taxi Medallion Portfolio Segment [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts	[1]	10		15
Recorded investment	[1]	$ 2,518		$ 3,926
Commercial Business and Other [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts				1
Recorded investment				$ 279

[1] Taxi medallion loans in the table above continue to pay as agreed, however the company records interest received on a cash basis.