Debt - Schedule of Debt (Details) - USD ($)	Aug. 31, 2017	May 31, 2017
Total debt	$ 19,188,250	$ 18,032,416
Debt issue costs, net of amortization	(198,483)	(228,426)
Debt	18,989,767	17,803,990
Less: Current portion	(2,710,820)	(2,493,236)
Long-term Debt	16,278,947	15,310,754
Term Note A Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% but Not Less Than 4.0%, Maturing January 7, 2019 [Member]
Total debt	4,457,243	4,626,191
Term Note B Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% but Not Less Than 4.0%, Maturing January 7, 2019 [Member]
Total debt	1,466,522	1,715,132
Term Note C Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% but Not Less Than 4.0%, Maturing August 4, 2020 [Member]
Total debt	1,776,190
Revolving Note Payable to International Bank of Commerce, Prime Rate of Interest Plus 0.5% but Not Less Than 4.0%, Due January 31, 2019 [Member]
Total debt	2,260,000	2,260,000
Term Note Payable by Gre to International Bank of Commerce, Interest Rate of 4.5%, Monthly Principal and Interest Payments of $26,215, Due January 31, 2019 [Member]
Total debt	2,795,134	2,841,285
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]
Total debt	1,322,628	1,396,448
Note Payable to Robert Rosene, 7.5% Interest, Due January 15, 2019 [Member]
Total debt	4,469,355	4,469,355
Note Payable to Yorktown Management & Financial Services, LLC, 5.0% Interest, Due February 28, 2019, Monthly Principal and Interest Payments of $20,629 [Member]
Total debt	357,021	413,969
Other Note Payable [Member]
Total debt	$ 284,157	$ 310,036