Note 15 - Concentrations of Credit Risk (Details Textual) - Credit Concentration Risk [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Commercial Real Estate Loans [Member]
Concentration Risk, Percentage	51.00%	52.00%
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	$ 340,414	$ 336,457
College Housing and Professional Office Buildings [Member]
Concentration Risk, Percentage	37.00%	36.00%
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	$ 247,198	$ 236,552
Residential [Member]
Concentration Risk, Percentage	25.00%	24.00%
Concentration Risk, Credit Risk, Financial Instrument, Maximum Exposure	$ 166,965	$ 157,718

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=84177426&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13537-108611

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