Leases - Schedule of Lease Cost (Details) - USD ($)	9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019
Leases [Abstract]
Financing lease expense - Amortization of right-of-use assets	$ 653,942	$ 775,530
Financing lease expense - Interest on lease liabilities	355,692	236,875
Operating lease expense	63,185	36,000
Short-term lease expense	1,207,008	1,136,617
Total	2,279,827	2,185,022
Cash paid for amounts included in the measurement of lease liabilities for finance leases - Operating cash flows	355,692	236,875
Cash paid for amounts included in the measurement of lease liabilities for finance leases - Financing cash flows	1,487,489	644,677
Cash paid for amounts included in the measurement of lease liabilities for operating leases - Operating cash flows	63,185	36,000
Right-of-use assets obtained in exchange for lease liabilities - Financing leases	612,124	4,667,380
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 7 months 6 days	3 years 1 month 6 days
Weighted-average remaining lease term (in years) - Operating leases	3 years	2 years 9 months 18 days
Weighted-average discount rate - Financing leases	7.10%	7.20%
Weighted-average discount rate - Operating leases	5.20%	5.00%