Note 3 - Available-for-sale Securities - Securities in a Continuous Loss Position (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale securities, less than 12 months, fair value	$ 3,885,207	$ 19,923,126
Available-for-sale securities, less than 12 months, gross unrealized losses	(40,454)	(400,360)
Available-for-sale securities, 12 months or more, fair value	11,312,360	5,351,384
Available-for-sale securities, 12 months or more, gross unrealized losses	(282,907)	(105,211)
Available-for-sale securities, fair value	15,197,567	25,274,510
Available-for-sale securities, gross unrealized losses	(323,361)	(505,571)
Collateralized Mortgage Backed Securities [Member]
Available-for-sale securities, less than 12 months, fair value	3,468,607	17,377,335
Available-for-sale securities, less than 12 months, gross unrealized losses	(39,099)	(337,092)
Available-for-sale securities, 12 months or more, fair value	9,763,879	5,351,384
Available-for-sale securities, 12 months or more, gross unrealized losses	(233,860)	(105,211)
Available-for-sale securities, fair value	13,232,486	22,728,719
Available-for-sale securities, gross unrealized losses	(272,959)	(442,303)
US Government Agencies Debt Securities [Member]
Available-for-sale securities, less than 12 months, fair value	0	2,525,737
Available-for-sale securities, less than 12 months, gross unrealized losses	0	(63,107)
Available-for-sale securities, 12 months or more, fair value	1,548,481	0
Available-for-sale securities, 12 months or more, gross unrealized losses	(49,047)	0
Available-for-sale securities, fair value	1,548,481	2,525,737
Available-for-sale securities, gross unrealized losses	(49,047)	(63,107)
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale securities, less than 12 months, fair value	416,600	20,054
Available-for-sale securities, less than 12 months, gross unrealized losses	(1,355)	(161)
Available-for-sale securities, 12 months or more, fair value	0	0
Available-for-sale securities, 12 months or more, gross unrealized losses	0	0
Available-for-sale securities, fair value	416,600	20,054
Available-for-sale securities, gross unrealized losses	$ (1,355)	$ (161)

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563

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