Note 5 - Fair Value - Quantitative Information About Level Fair Value Measurements (Details) - Fair Value, Measurements, Nonrecurring [Member]	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Impaired loans/leases	$ 5,564,760	$ 8,972,337
OREO	$ 13,770,025	$ 14,642,973
Minimum [Member] \| Measurement Input, Appraisal Adjustment Rate [Member]
Impaired loans/leases, measurment input	(10)
OREO, measurment input	0
Maximum [Member] \| Measurement Input, Appraisal Adjustment Rate [Member]
Impaired loans/leases, measurment input	(30)
OREO, measurment input	(35)

Value of input used to measure real estate owned by financial institution by financial institution which is not directly related to its business.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Name:	us-gaap_OtherRealEstateOwnedMeasurementInput
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant