Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2019
Feb. 21, 2020
Jun. 28, 2019
Cover page.      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2019    
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 Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
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 Public Float     $ 645,970,269
Entity Common Stock, Shares Outstanding   136,790,094  
Entity Central Index Key 0001708035    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Amendment Flag false