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Share-Based Compensation (Details) (USD $)
3 Months Ended
Mar. 31, 2015
MSUs  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Awards granted 473,728us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= usg_MarketShareUnitsMember
Weighted average fair value $ 30.06us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= usg_MarketShareUnitsMember
Expected volatility 42.70%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= usg_MarketShareUnitsMember
Risk-free rate 1.09%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= usg_MarketShareUnitsMember
[1]
Expected term (in years) 2 years 11 months 11 days [2]
Expected dividends $ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments
/ us-gaap_AwardTypeAxis
= usg_MarketShareUnitsMember
Performance Shares  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Awards granted 147,290us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
Weighted average fair value $ 30.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
Expected volatility 42.70%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
Risk-free rate 1.09%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
[1]
Expected term (in years) 2 years 11 months 11 days [2]
Expected dividends $ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments
/ us-gaap_AwardTypeAxis
= us-gaap_PerformanceSharesMember
RSUs  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Awards granted 48,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
Weighted average fair value $ 27.69us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
[1] The risk-free rate was based on zero coupon U.S. government issues at the time of grant.
[2] The expected term represents the period from the valuation date to the end of the performance period.