Leases - Lease assets and liabilities (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Current
Prepaid expenses and other current assets	$ 317,029	$ 36,097
Noncurrent
Operating lease right-of-use assets	1,250,157	4,439,212
Total lease right-of-use assets	1,567,186	4,475,309
Current
Current maturities of operating leases	628,161	755,751
Noncurrent
Noncurrent operating leases	930,072	3,836,475
Total lease obligations	$ 1,558,233	$ 4,592,226
Operating leases, weighted average remaining lease term	3 years 2 months 12 days	17 years 9 months 18 days
Operating leases, weighted average discount rate	4.33%	4.59%