Note 5 - Loans - Troubled Debt Restructurings That Are Performing According to Their Restructured Terms (Details)		3 Months Ended		6 Months Ended		12 Months Ended
		Jun. 30, 2019 USD ($)	Jun. 30, 2018	Jun. 30, 2019 USD ($)	Jun. 30, 2018	Dec. 31, 2018 USD ($)
Financing Receivable, Modifications, Number of Contracts		0	0	0	0
Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts				23		31
Recorded investment		$ 6,289,000		$ 6,289,000		$ 8,365,000
Multi-Family Residential [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts				7		7
Recorded investment		1,894,000		$ 1,894,000		$ 1,916,000
One-To-Four Family - Mixed Used Property [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts				5		5
Recorded investment		1,660,000		$ 1,660,000		$ 1,692,000
One-To-Four Family - Residential [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts				3		3
Recorded investment		542,000		$ 542,000		$ 552,000
Taxi Medallion Portfolio Segment [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts	[1]			8		15
Recorded investment	[1]	2,193,000		$ 2,193,000		$ 3,926,000
Commercial Business and Other [Member] | Performing Financial Instruments [Member]
Financing Receivable, Modifications, Number of Contracts				0		1
Recorded investment		$ 0		$ 0		$ 279,000

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