Earnings Per Share - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2020	Nov. 30, 2019
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ 873,180	$ 304,428	$ 1,733,381	$ 746,678
Weighted-average common shares outstanding - Basic	28,361,201	28,361,201	28,361,201	28,361,201
Income per share of common stock - Basic	$ 0.03	$ 0.01	$ 0.06	$ 0.03
Net income attributable to common stockholders	$ 873,180	$ 304,428	$ 1,733,381	$ 746,678
Add: Preferred stock dividends for assumed conversion	81,918		163,836
Net Income allocated to common stockholders	$ 955,098	$ 304,428	$ 1,897,217	$ 746,678
Weighted-average shares outstanding - basic	28,361,201	28,361,201	28,361,201	28,361,201
Incremental shares from assumed conversion of options, warrants and preferred stock, as appropriate	4,002,482	639,959	4,002,150	644,231
Weighted average common stock outstanding - diluted	32,363,683	29,001,160	32,363,351	29,005,432
Income per share of common stock - diluted	$ 0.03	$ 0.01	$ 0.06	$ 0.03