Leases - Lease assets and liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current
Prepaid expenses and other current assets	$ 36,097
Noncurrent
Operating lease right-of-use assets	4,439,212	$ 0
Total lease right-of-use assets	4,475,309
Current
Current maturities of operating leases	755,751	0
Noncurrent
Noncurrent operating leases	3,836,475	$ 0
Total lease obligations	$ 4,592,226
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current maturities of operating leases
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Noncurrent operating leases
Operating leases, weighted average remaining lease term	17 years 9 months 18 days
Operating leases, weighted average discount rate	4.59%