Document and Entity Information
12 Months Ended
Dec. 31, 2018
Document and Entity Information [Abstract]  
Entity Registrant Name Ferroglobe PLC
Entity Central Index Key 0001639877
Document Type 20-F
Document Period End Date Dec. 31, 2018
Amendment Flag false
Current Fiscal Year End Date --12-31
Entity Well-known Seasoned Issuer No
Entity Voluntary Filers No
Entity Current Reporting Status Yes
Entity Filer Category Large Accelerated Filer
Entity Common Stock, Shares Outstanding 169,122,682
Entity Emerging Growth Company false
Entity Shell Company false
Document Fiscal Year Focus 2018
Document Fiscal Period Focus FY