Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2017
Mar. 19, 2018
Document And Entity Information [Abstract]    
Entity Registrant Name PQ Group Holdings Inc.  
Entity Central Index Key 0001708035  
Document Type 10-K  
Document Period End Date Dec. 31, 2017  
Amendment Flag false  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus FY  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Well-known Seasoned Issuer No  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes  
Entity Common Stock, Shares Outstanding   135,240,866
Entity Public Float $ 641,036,201