Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($)	Feb. 29, 2020	May 31, 2019
Debt Instrument [Line Items]
Total long-term debt	$ 18,660,207	$ 22,697,464
Debt issuance costs, net of amortization	(37,176)	(37,686)
Total debt, net of debt issuance costs	18,623,031	22,659,778
Less: Current portion of long-term debt	(3,525,314)	(3,030,630)
Long-term debt, net of current portion and debt issue costs	15,097,717	19,629,148
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	2,664,063	3,234,947
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	1,228,697	1,399,490
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	1,293,713	1,744,235
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	756,372	927,199
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	2,919,586	3,398,247
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	848,448	876,934
Term Loan H Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% But Not Less Than 5.25%, Maturing January 1, 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	499,585
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	1,090,000	3,205,000
Note Payable to First Bank, Prime Rate of Interest Plus 1.45% But Not Less Than 4.95%, Monthly Principal and Interest Payment of $30,628, Due August 21, 2021, Secured by Production Equipment [Member]
Debt Instrument [Line Items]
Total long-term debt	561,105	800,488
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	2,312,223	2,461,116
Note Payable to Robert Rosene, 7.5% Interest, Due January 15, 2022 [Member]
Debt Instrument [Line Items]
Total long-term debt	4,297,169	4,426,631
Other [Member]
Debt Instrument [Line Items]
Total long-term debt	$ 189,246	$ 223,177