Document and Entity Information
9 Months Ended
Sep. 30, 2018
Document and Entity Information [Abstract]  
Entity Registrant Name USG CORP
Entity Central Index Key 0000757011
Document Type 10-Q
Document Period End Date Sep. 30, 2018
Amendment Flag false
Document Fiscal Year Focus 2018
Document Fiscal Period Focus Q3
Current Fiscal Year End Date --12-31
Entity Filer Category Large Accelerated Filer
Entity Common Stock, Shares Outstanding 139,755,820
Entity Emerging Growth Company false
Entity Small Business false