Leases - Schedule of Lease Cost (Details) - USD ($)	6 Months Ended
	Nov. 30, 2019	Nov. 30, 2018
Leases [Abstract]
Financing lease expense - Amortization of right-of-use assets	$ 416,000	$ 449,000
Financing lease expense - Interest on lease liabilities	220,255	126,514
Operating lease expense	39,650	24,000
Short-term lease expense	797,835	749,843
Total	1,473,740	1,349,357
Cash paid for amounts included in the measurement of lease liabilities for finance leases - Operating cash flows	220,255	126,514
Cash paid for amounts included in the measurement of lease liabilities for finance leases - Financing cash flows	911,529	1,333,699
Cash paid for amounts included in the measurement of lease liabilities for operating leases - Operating cash flows	39,650	24,000
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 4 months 24 days
Weighted-average remaining lease term (in years) - Operating leases	3 years 6 months	3 years 1 month 6 days
Weighted-average discount rate - Financing leases	7.10%	7.00%
Weighted-average discount rate - Operating leases	5.30%	5.00%