Leases - Schedule of Lease Cost (Details) - USD ($)	3 Months Ended
	Aug. 31, 2019	Aug. 31, 2018
Leases [Abstract]
Financing lease expense - Amortization of right-of-use assets	$ 208,157	$ 208,245
Financing lease expense - Interest on lease liabilities	121,151	67,656
Operating lease expense	19,179	12,000
Short-term lease expense	368,611	342,819
Total	717,098	630,720
Cash paid for amounts included in the measurement of lease liabilities for finance leases - Operating cash flows	121,151	67,656
Cash paid for amounts included in the measurement of lease liabilities for finance leases - Financing cash flows	419,177	608,094
Cash paid for amounts included in the measurement of lease liabilities for operating leases - Operating cash flows	19,179	12,000
Right-of-use assets obtained in exchange for lease liabilities - Financing leases		2,333,333
Right-of-use assets obtained in exchange for lease liabilities - Operating leases	$ 67,750
Weighted-average remaining lease term (in years) - Financing leases	3 years 2 months 12 days	3 years 2 months 12 days
Weighted-average remaining lease term (in years) - Operating leases	3 years 4 months 24 days	3 years 3 months 19 days
Weighted-average discount rate - Financing leases	7.50%	6.90%
Weighted-average discount rate - Operating leases	5.20%	5.00%