Document and Entity Information - shares
6 Months Ended
Nov. 30, 2016
Jan. 02, 2017
Document and Entity Information    
Entity Registrant Name Mistras Group, Inc.  
Entity Central Index Key 0001436126  
Document Type 10-Q  
Document Period End Date Nov. 30, 2016  
Amendment Flag false  
Current Fiscal Year End Date --05-31  
Entity Current Reporting Status Yes  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   28,796,487
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q2