Variable Interest Entities (VIE)	12 Months Ended
May 31, 2018
Variable Interest Entity, Measure of Activity [Abstract]
Variable Interest Entities (VIE)	Note 14. VARIABLE INTEREST ENTITIES (VIE) Greystone Real Estate, L.L.C. GRE, is owned by Warren Kruger, President and CEO, and Robert Rosene, a member of the Board of Directors. GRE was created solely to own and lease buildings that GSM occupies in Bettendorf, Iowa. The buildings, having a carrying value of $3,012,421 and $3,128,293 at May 31, 2018 and 2017, respectively, serve as collateral for GRE’s debt. The debt had a carrying value of $2,652,428 and $2,841,285 at May 31, 2018 and 2017, respectively.

The entire disclosure for a variable interest entity (VIE), including but not limited to, judgments and assumptions in determining whether to consolidate and in identifying the primary beneficiary, gain (loss) recognized on the initial consolidation of the VIE, terms of arrangements, amounts and classification of the VIE's assets and liabilities, and the entity's maximum exposure to loss.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-URI http://asc.fasb.org/topic&trid=2197479

Name:	us-gaap_VariableInterestEntityDisclosureTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration