Share-Based Compensation - Terms of Awards Granted (Details)	9 Months Ended
Sep. 30, 2018
MSUs
Share Based Compensation [Abstract]
Minimum of range for number of shares earned	0.00%
Maximum of range for number of shares earned	150.00%
Vesting period	3 years
Performance Shares
Share Based Compensation [Abstract]
Minimum of range for number of shares earned	0.00%
Maximum of range for number of shares earned	200.00%
Vesting period	3 years
RSUs (e)
Share Based Compensation [Abstract]
Maximum of range for number of shares earned	100.00%

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based compensation arrangement by share-based payment award terms of award maximum.

+ References

No definition available.

+ Details

Name:	usg_ShareBasedCompensationArrangementByShareBasedPaymentAwardTermsOfAwardMaximum
Namespace Prefix:	usg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based compensation arrangement by share-based payment award terms of award minimum.

+ References

No definition available.

+ Details

Name:	usg_ShareBasedCompensationArrangementByShareBasedPaymentAwardTermsOfAwardMinimum
Namespace Prefix:	usg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

A textual description of the accounting policy for share-based grants expense recognition and the plan under which awards are granted.

+ References

No definition available.

+ Details

Name:	usg_ShareBasedCompensationTextualAbstract
Namespace Prefix:	usg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=usg_MarketShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: