Annual report pursuant to Section 13 and 15(d)

Cover

v3.20.4
Cover - USD ($)
 12 Months Ended
Dec. 31, 2020
Mar. 12, 2021
Jun. 30, 2020
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 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 Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Entity Shell Company false    
Entity Public Float     $ 537,729,982
Entity Common Stock, Shares Outstanding   136,937,196  
Entity Central Index Key 0001708035    
Current Fiscal Year End Date --12-31    
Document Fiscal Year Focus 2020    
Document Fiscal Period Focus FY    
Amendment Flag false