Investments (Details Textual) - USD ($)
|
Sep. 30, 2018 |
Dec. 31, 2017 |
| Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment |
$ 22,869,924
|
$ 28,762,231
|
| Held-to-maturity Securities [Member] |
|
|
| Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment |
22,869,924
|
|
| Current Investments [Member] |
|
|
| Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment |
18,949,924
|
21,556,857
|
| 2019 Maturity Investments [Member] | Held-to-maturity Securities [Member] |
|
|
| Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment |
8,770,000
|
|
| Long Term Investments [Member] |
|
|
| Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment |
3,920,000
|
$ 7,205,374
|
| 2018 Maturity Investments [Member] | Held-to-maturity Securities [Member] |
|
|
| Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment |
$ 14,100,000
|
|