XML 98 R52.htm IDEA: XBRL DOCUMENT v2.4.1.9
Significant Accounting Policies (Details)
Dec. 31, 2014
Feb. 27, 2014
Minimum    
Schedule of Equity Method Investments [Line Items]    
Ownership percentage interest 20.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		  
Maximum    
Schedule of Equity Method Investments [Line Items]    
Ownership percentage interest 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		  
USG Boral Building Products    
Schedule of Equity Method Investments [Line Items]    
Ownership percentage interest 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= usg_USGBoralBuildingProductsMember		  
Co-venturer | USG Boral Building Products    
Schedule of Equity Method Investments [Line Items]    
Ownership percentage by joint venture partner   50.00%usg_EquityMethodInvestmentOwnershipPercentagebyJointVenturePartner
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_CoVenturerMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= usg_USGBoralBuildingProductsMember