Note 2 - Available-for-sale Securities - Securities in a Continuous Loss Position (Details) - USD ($)
|
Mar. 31, 2018 |
Dec. 31, 2017 |
| Available-for-sale securities, less than 12 months, fair value |
$ 13,488,153
|
$ 3,885,207
|
| Available-for-sale securities, less than 12 months, gross unrealized losses |
(235,498)
|
(40,454)
|
| Available-for-sale securities, 12 months or more, fair value |
11,077,219
|
11,312,360
|
| Available-for-sale securities, 12 months or more, gross unrealized losses |
(426,824)
|
(282,907)
|
| Available-for-sale securities, fair value |
24,565,372
|
15,197,567
|
| Available-for-sale securities, gross unrealized losses |
(662,322)
|
(323,361)
|
| Asset-backed Securities [Member] |
|
|
| Available-for-sale securities, less than 12 months, fair value |
12,464,292
|
3,468,607
|
| Available-for-sale securities, less than 12 months, gross unrealized losses |
(227,176)
|
(39,099)
|
| Available-for-sale securities, 12 months or more, fair value |
9,657,488
|
9,763,879
|
| Available-for-sale securities, 12 months or more, gross unrealized losses |
(361,894)
|
(233,860)
|
| Available-for-sale securities, fair value |
22,121,780
|
13,232,486
|
| Available-for-sale securities, gross unrealized losses |
(589,070)
|
(272,959)
|
| US Government Agencies Debt Securities [Member] |
|
|
| Available-for-sale securities, less than 12 months, fair value |
360,605
|
|
| Available-for-sale securities, less than 12 months, gross unrealized losses |
(5,948)
|
|
| Available-for-sale securities, 12 months or more, fair value |
1,419,731
|
1,548,481
|
| Available-for-sale securities, 12 months or more, gross unrealized losses |
(64,930)
|
(49,047)
|
| Available-for-sale securities, fair value |
1,780,336
|
1,548,481
|
| Available-for-sale securities, gross unrealized losses |
(70,878)
|
(49,047)
|
| US States and Political Subdivisions Debt Securities [Member] |
|
|
| Available-for-sale securities, less than 12 months, fair value |
663,256
|
416,600
|
| Available-for-sale securities, less than 12 months, gross unrealized losses |
(2,374)
|
(1,355)
|
| 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 |
663,256
|
416,600
|
| Available-for-sale securities, gross unrealized losses |
$ (2,374)
|
$ (1,355)
|