Note 2 - Available-for-sale Securities - Carrying Amount of Securities and Fair Value (Details) - USD ($)
|
Mar. 31, 2018 |
Dec. 31, 2017 |
| Available-for-sale securities, gross amortized cost |
$ 26,750,904
|
$ 24,707,857
|
| Available-for-sale securities, gross unrealized gains |
7,078
|
15,385
|
| Available-for-sale securities, gross unrealized losses |
(662,322)
|
(323,361)
|
| Available-for-sale securities, fair value |
26,095,660
|
24,399,881
|
| Asset-backed Securities [Member] |
|
|
| Available-for-sale securities, gross amortized cost |
23,238,466
|
21,028,794
|
| Available-for-sale securities, gross unrealized gains |
6,317
|
12,757
|
| Available-for-sale securities, gross unrealized losses |
(589,070)
|
(272,959)
|
| Available-for-sale securities, fair value |
22,655,713
|
20,768,592
|
| US Government Agencies Debt Securities [Member] |
|
|
| Available-for-sale securities, gross amortized cost |
1,851,214
|
2,006,786
|
| Available-for-sale securities, gross unrealized gains |
|
44
|
| Available-for-sale securities, gross unrealized losses |
(70,878)
|
(49,047)
|
| Available-for-sale securities, fair value |
1,780,336
|
1,957,783
|
| US States and Political Subdivisions Debt Securities [Member] |
|
|
| Available-for-sale securities, gross amortized cost |
1,661,224
|
1,672,277
|
| Available-for-sale securities, gross unrealized gains |
761
|
2,584
|
| Available-for-sale securities, gross unrealized losses |
(2,374)
|
(1,355)
|
| Available-for-sale securities, fair value |
$ 1,659,611
|
$ 1,673,506
|