Leases - Summary of Lease Activity (Details) - USD ($)	6 Months Ended
	Nov. 30, 2020	Nov. 30, 2019
Leases [Abstract]
Financing lease expense - Amortization of right-of-use assets	$ 505,935	$ 416,000
Financing lease expense - Interest on lease liabilities	156,059	220,255
Operating lease expense	40,941	39,650
Short-term lease expense	723,443	797,835
Total	1,426,378	1,473,740
Cash paid for amounts included in the measurement of lease liabilities for finance leases - Operating cash flows	156,059	220,255
Cash paid for amounts included in the measurement of lease liabilities for finance leases - Financing cash flows	955,580	911,529
Cash paid for amounts included in the measurement of lease liabilities for operating leases - Operating cash flows	40,941	39,650
Right-of-use assets obtained in exchange for lease liabilities - Operating leases		$ 67,750
Weighted-average remaining lease term (in years) - Financing leases	2 years 3 months 19 days	3 years 2 months 12 days
Weighted-average remaining lease term (in years) - Operating leases	2 years 4 months 24 days	3 years 6 months
Weighted-average discount rate - Financing leases	7.40%	7.10%
Weighted-average discount rate - Operating leases	5.20%	5.30%