Note 5 - Loans - Impaired Loans (Details) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Recorded investment, with no related allowance recorded	$ 19,186,000		$ 19,186,000		$ 18,869,000
Unpaid principal balance, with no related allowance recorded	28,444,000		28,444,000		28,156,000
Recorded investment, with an allowance recorded	3,305,000		3,305,000		6,650,000
Unpaid principal balance, with an allowance recorded	3,305,000		3,305,000		6,650,000
Related allowance	372,000		372,000		1,160,000
Loans designated as criticized or classified	41,844,000		41,844,000		53,030,000
Average Recorded Investment, With no related allowance recorded	19,231,000	$ 37,871,000	19,110,000	$ 36,236,000
Interest Income Recognized, With no related allowance recorded	91,000	522,000	177,000	757,000
Average Recorded Investment, With an allowance recorded	3,433,000	4,142,000	4,505,000	4,826,000
Interest Income Recognized, With an allowance recorded	32,000	53,000	64,000	100,000
Multi-family Residential Portfolio Segment [Member]
Loans designated as criticized or classified	3,515,000		3,515,000		6,664,000
Commercial Real Estate Portfolio Segment [Member]
Loans designated as criticized or classified	1,926,000		1,926,000		4,432,000
One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Loans designated as criticized or classified	3,034,000		3,034,000		3,233,000
One-To-Four Family - Residential Portfolio Segment [Member]
Loans designated as criticized or classified	6,647,000		6,647,000		7,222,000
Construction Portfolio Segment [Member]
Loans designated as criticized or classified	0		0		730,000
Small Business Administration Portfolio Segment [Member]
Loans designated as criticized or classified	170,000		170,000		620,000
Taxi Medallion Portfolio Segment [Member]
Loans designated as criticized or classified	3,555,000		3,555,000		4,539,000
Commercial Business and Other Portfolio Segment [Member]
Loans designated as criticized or classified	22,997,000		22,997,000		25,590,000
Mortgage Receivable [Member]
Related allowance	194,000		194,000		294,000
Loans designated as criticized or classified	15,254,000		15,254,000		15,922,000
Unpaid principal balance, total impaired loans	15,905,000		15,905,000		16,618,000
Average Recorded Investment, Total Impaired Loans	15,429,000	27,246,000	15,593,000	28,673,000
Interest Income Recognized, Total Impaired Loans	75,000	176,000	135,000	368,000
Mortgage Receivable [Member] \| Multi-family Residential Portfolio Segment [Member]
Recorded investment, with no related allowance recorded	2,856,000		2,856,000		3,225,000
Unpaid principal balance, with no related allowance recorded	3,199,000		3,199,000		3,568,000
Recorded investment, with an allowance recorded	1,263,000		1,263,000		1,275,000
Unpaid principal balance, with an allowance recorded	1,263,000		1,263,000		1,275,000
Related allowance	96,000		96,000		100,000
Average Recorded Investment, With no related allowance recorded	2,846,000	4,431,000	2,972,000	4,651,000
Interest Income Recognized, With no related allowance recorded	9,000	16,000	18,000	36,000
Average Recorded Investment, With an allowance recorded	1,266,000	2,203,000	1,269,000	2,208,000
Interest Income Recognized, With an allowance recorded	18,000	30,000	36,000	59,000
Mortgage Receivable [Member] \| Commercial Real Estate Portfolio Segment [Member]
Recorded investment, with no related allowance recorded	1,555,000		1,555,000		1,435,000
Unpaid principal balance, with no related allowance recorded	1,555,000		1,555,000		1,435,000
Average Recorded Investment, With no related allowance recorded	1,326,000	5,847,000	1,362,000	6,266,000
Interest Income Recognized, With no related allowance recorded	15,000	52,000	15,000	126,000
Average Recorded Investment, With an allowance recorded			0	662,000
Interest Income Recognized, With an allowance recorded			0	0
Mortgage Receivable [Member] \| One-To-Four Family - Mixed-Use Property Portfolio Segment [Member]
Recorded investment, with no related allowance recorded	2,433,000		2,433,000		1,913,000
Unpaid principal balance, with no related allowance recorded	2,574,000		2,574,000		2,113,000
Recorded investment, with an allowance recorded	997,000		997,000		1,185,000
Unpaid principal balance, with an allowance recorded	997,000		997,000		1,185,000
Related allowance	49,000		49,000		143,000
Average Recorded Investment, With no related allowance recorded	2,208,000	4,397,000	2,110,000	4,337,000
Interest Income Recognized, With no related allowance recorded	17,000	39,000	34,000	80,000
Average Recorded Investment, With an allowance recorded	1,001,000	1,212,000	1,062,000	1,217,000
Interest Income Recognized, With an allowance recorded	10,000	15,000	20,000	24,000
Mortgage Receivable [Member] \| One-To-Four Family - Residential Portfolio Segment [Member]
Recorded investment, with no related allowance recorded	5,759,000		5,759,000		6,490,000
Unpaid principal balance, with no related allowance recorded	5,926,000		5,926,000		6,643,000
Recorded investment, with an allowance recorded	391,000		391,000		399,000
Unpaid principal balance, with an allowance recorded	391,000		391,000		399,000
Related allowance	49,000		49,000		51,000
Average Recorded Investment, With no related allowance recorded	5,914,000	8,382,000	6,106,000	8,678,000
Interest Income Recognized, With no related allowance recorded	2,000	10,000	4,000	25,000
Average Recorded Investment, With an allowance recorded	393,000	409,000	395,000	411,000
Interest Income Recognized, With an allowance recorded	4,000	4,000	8,000	8,000
Mortgage Receivable [Member] \| Construction Portfolio Segment [Member]
Average Recorded Investment, With no related allowance recorded	475,000	365,000	317,000	243,000
Interest Income Recognized, With no related allowance recorded	0	10,000	0	10,000
Non-Mortgage Loans [Member]
Related allowance	178,000		178,000		866,000
Loans designated as criticized or classified	7,237,000		7,237,000		9,597,000
Unpaid principal balance, total impaired loans	15,844,000		15,844,000		18,188,000
Average Recorded Investment, Total Impaired Loans	7,235,000	14,767,000	8,022,000	12,389,000
Interest Income Recognized, Total Impaired Loans	48,000	399,000	106,000	489,000
Non-Mortgage Loans [Member] \| Small Business Administration Portfolio Segment [Member]
Recorded investment, with no related allowance recorded	1,224,000		1,224,000		1,267,000
Unpaid principal balance, with no related allowance recorded	1,494,000		1,494,000		1,609,000
Average Recorded Investment, With no related allowance recorded	1,226,000	74,000	1,239,000	95,000
Interest Income Recognized, With no related allowance recorded	0	1,000	0	2,000
Non-Mortgage Loans [Member] \| Taxi Medallion Portfolio Segment [Member]
Recorded investment, with no related allowance recorded	3,555,000		3,555,000		4,539,000
Unpaid principal balance, with no related allowance recorded	9,772,000		9,772,000		12,788,000
Average Recorded Investment, With no related allowance recorded	3,723,000	6,421,000	3,995,000	6,559,000
Interest Income Recognized, With no related allowance recorded	48,000	86,000	106,000	168,000
Non-Mortgage Loans [Member] \| Commercial Business and Other Portfolio Segment [Member]
Recorded investment, with no related allowance recorded	1,804,000		1,804,000		0
Unpaid principal balance, with no related allowance recorded	3,924,000		3,924,000		0
Recorded investment, with an allowance recorded	654,000		654,000		3,791,000
Unpaid principal balance, with an allowance recorded	654,000		654,000		3,791,000
Related allowance	178,000		178,000		$ 866,000
Average Recorded Investment, With no related allowance recorded	1,513,000	7,954,000	1,009,000	5,407,000
Interest Income Recognized, With no related allowance recorded	0	308,000	0	310,000
Average Recorded Investment, With an allowance recorded	773,000	318,000	1,779,000	328,000
Interest Income Recognized, With an allowance recorded	$ 0	$ 4,000	$ 0	$ 9,000

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524

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