Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

v3.10.0.1
Document and Entity Information - shares
9 Months Ended
Sep. 30, 2018
Nov. 02, 2018
Document And Entity Information [Abstract]    
Entity Registrant Name PQ Group Holdings Inc.  
Entity Central Index Key 0001708035  
Document Type 10-Q  
Document Period End Date Sep. 30, 2018  
Amendment Flag false  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q3  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Emerging Growth Company false  
Entity Small Business false  
Entity Common Stock, Shares Outstanding   135,590,622