Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($)	Nov. 30, 2020	May 31, 2020
Debt Instrument [Line Items]
Total long-term debt	$ 19,115,998	$ 22,781,896
Debt issuance costs, net of amortization	(33,306)	(35,886)
Total debt, net of debt issuance costs	19,082,692	22,746,010
Less: Current portion of long-term debt	(5,195,878)	(4,416,377)
Long-term debt, net of current portion and debt issue costs	13,886,814	18,329,633
Term Loan A Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% But Not Less Than 4.0%, Maturing April 30, 2023 [Member]
Debt Instrument [Line Items]
Total long-term debt	2,046,067	2,459,854
Term Loan C Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% But Not Less Than 4.0%, Maturing August 4, 2024 [Member]
Debt Instrument [Line Items]
Total long-term debt	1,037,291	1,165,774
Term Loan D Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% But Not Less Than 4.75%, Maturing January 10, 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	815,983	1,136,455
Term Loan E Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% But Not Less Than 4.75%, Maturing January 10, 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	573,469	696,174
Term Loan F Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% But Not Less Than 5.25%, Maturing February 29, 2024 [Member]
Debt Instrument [Line Items]
Total long-term debt	2,398,571	2,752,293
Term Loan G Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% But Not Less Than 5.25%, Maturing April 30, 2024 [Member]
Debt Instrument [Line Items]
Total long-term debt	814,314	837,811
Revolving Loan Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% But Not Less Than 5.5%, Due January 31, 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	1,100,000	2,540,000
Paycheck Protection Program Note, Interest Rate of 1.0%, Maturing April 13, 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	3,034,000	3,034,000
Term Loan Payable by GRE to International Bank of Commerce, Interest Rate of 5.5%, Monthly Principal and Interest Payment of $27,688, Due April 30, 2023 [Member]
Debt Instrument [Line Items]
Total long-term debt	2,157,320	2,261,425
Term Note Payable to Great Western Bank, Interest Rate of 3.7%, Monthly Principal and Interest Payments of $27,593, due March 19, 2025, Secured by Certain Equipment [Member]
Debt Instrument [Line Items]
Total long-term debt	1,323,295	1,461,726
Note Payable to Robert Rosene, 7.5% Interest, Due January 15, 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	3,649,878	4,253,228
Other [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 165,810	$ 183,156