Reconciliation of Liability Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Feb. 29, 2020	Feb. 29, 2020	May 31, 2019	May 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		$ 2,407,269	$ 1,323,732
Exercises	$ 5,427,687
Fair value adjustments				$ (3,855,468)
Ending Balance	$ 2,108,398	2,108,398	2,407,269	1,323,732
Convertible notes [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value adjustments		(2,005,137)	(921,600)
Warrant [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Exercises		(2,404,097)
Fair value adjustments		$ 4,110,363	(744,869)
Investor Warrants Issued with Registered Direct Equity Offering
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Warrants issued				4,360,000
Placement Agent Warrants Issued with Registered Direct Equity Offering
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Warrants issued				$ 819,200
Inception date value of redemption provision - warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Warrants issued			$ 2,750,006