Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

Document and Entity Information - shares
3 Months Ended
Mar. 31, 2020
May 06, 2020
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2020  
Document Transition Report false  
Entity File Number 001-38221  
Entity Registrant Name PQ Group Holdings Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 81-3406833  
Entity Address, Address Line One 300 Lindenwood Drive  
Entity Address, City or Town Malvern,  
Entity Address, State or Province PA  
Entity Address, Postal Zip Code 19355  
City Area Code (610)  
Local Phone Number 651-4400  
Title of 12(b) Security Common stock, par value $0.01 per share  
Trading Symbol PQG  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   136,591,952
Entity Central Index Key 0001708035  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q1  
Amendment Flag false