Litigation	9 Months Ended
Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Litigation	Litigation WALLBOARD PRICING CLASS ACTION LAWSUITS In late 2012, USG Corporation and United States Gypsum Company were named as defendants in putative class action lawsuits alleging that since at least September 2011, U.S. wallboard manufacturers conspired to fix and raise the price of gypsum wallboard sold in the United States and to effectuate the alleged conspiracy by ending the practice of providing job quotes on wallboard. These lawsuits are consolidated for pretrial proceedings in multi-district litigation in the United States District Court for the Eastern District of Pennsylvania, under the title In re: Domestic Drywall Antitrust Litigation, MDL No. 2437. One group of plaintiffs brings their claims on behalf of a class of entities that purchased gypsum wallboard in the United States directly from any of the defendants or their affiliates from January 1, 2012 to the present. The second group of plaintiffs brings their claims on behalf of indirect purchasers of gypsum wallboard who from January 1, 2012 through the present indirectly purchased wallboard in the United States from the defendants or their affiliates for end use and not for resale. Similar lawsuits have been filed in Quebec, Ontario and British Columbia courts on behalf of purchasers of wallboard in Canada. The Canadian lawsuits also name as defendants CGC Inc., our Canadian operating subsidiary, as well as other Canadian and U.S. wallboard manufacturers. USG has denied the allegations made in these wallboard pricing lawsuits, believes these cases are without merit, and that USG’s pricing and selling policies were and are made independently and in full compliance with the law. Class action antitrust litigation in the United States, however, is expensive, protracted, and carries the risk of triple damages and joint and several liability. To avoid the expense, risk and further distraction of management, in late 2014, we agreed to a settlement of the U.S. direct and indirect purchaser plaintiff class actions and in the third quarter of 2014, we recorded a $48 million charge for the settlements ($39.25 million for the direct purchaser settlement and $8.75 million for the indirect purchaser settlement). On August 20, 2015, the court entered final judgment orders approving both the direct and indirect purchaser settlements. No member of the direct purchaser class appealed from the final judgment order approving the direct purchaser settlement, and therefore, that settlement should be final. One person appealed from the final judgment order approving the indirect purchaser settlement, and therefore that settlement is not yet final. We believe that the appeal is without merit and that the indirect purchaser settlement order will be affirmed on appeal, but the indirect purchaser settlement will not become final unless and until the appeal is favorably resolved. The settlement of the U.S. class action lawsuits described above does not include the Canadian lawsuits. At this stage of the Canadian lawsuits, we are not able to estimate the amount, if any, of any reasonably possible loss or range of reasonably possible losses. We believe, however, that these Canadian lawsuits will not have a material effect on our business, financial condition, operating results or cash flows. In addition to the class action lawsuits, in the first quarter of 2015, USG and seven other wallboard manufacturers were named as defendants in a lawsuit filed in federal court in California by twelve homebuilders asserting individual claims similar to the claims asserted in the U.S. class action lawsuits. These homebuilders opted out of the class action settlements, and their lawsuit has been transferred to the United States District Court for the Eastern District of Pennsylvania that is presiding over the U.S. class action lawsuits. We believe that the cost, if any, of resolving these homebuilders’ claims will not materially increase our exposure above the $48 million agreed to in the U.S. class action settlements. ENVIRONMENTAL LITIGATION We have been notified by state and federal environmental protection agencies of possible involvement as one of numerous “potentially responsible parties” in a number of Superfund sites in the United States. As a potentially responsible party, we may be responsible to pay for some part of the cleanup of hazardous waste at those sites. In most of these sites, our involvement is expected to be minimal. In addition, we are involved in environmental cleanups of other property that we own or owned. As of both September 30, 2015 and December 31, 2014, we had an accrual of $16 million for our probable and reasonably estimable liability in connection with these matters. Our accruals take into account all known or estimated undiscounted costs associated with these sites, including site investigations and feasibility costs, site cleanup and remediation, certain legal costs, and fines and penalties, if any. However, we continue to review these accruals as additional information becomes available and revise them as appropriate. Based on the information known to us, we believe these environmental matters will not have a material effect on our business, financial condition, operating results or cash flows. OTHER LITIGATION We are named as defendants in other claims and lawsuits arising from our operations, including claims and lawsuits arising from the operation of our vehicles, product performance or warranties, personal injury and commercial disputes. We believe that we have properly accrued for our probable liability in connection with these claims and suits, taking into account the probability of liability, whether our exposure can be reasonably estimated and, if so, our estimate of our liability or the range of our liability. We do not expect these or any other litigation matters involving USG to have a material effect on our business, financial condition, operating results or cash flows.

Litigation

WALLBOARD PRICING CLASS ACTION LAWSUITS

In late 2012, USG Corporation and United States Gypsum Company were named as defendants in putative class action lawsuits alleging that since at least September 2011, U.S. wallboard manufacturers conspired to fix and raise the price of gypsum wallboard sold in the United States and to effectuate the alleged conspiracy by ending the practice of providing job quotes on wallboard. These lawsuits are consolidated for pretrial proceedings in multi-district litigation in the United States District Court for the Eastern District of Pennsylvania, under the title In re: Domestic Drywall Antitrust Litigation, MDL No. 2437. One group of plaintiffs brings their claims on behalf of a class of entities that purchased gypsum wallboard in the United States directly from any of the defendants or their affiliates from January 1, 2012 to the present. The second group of plaintiffs brings their claims on behalf of indirect purchasers of gypsum wallboard who from January 1, 2012 through the present indirectly purchased wallboard in the United States from the defendants or their affiliates for end use and not for resale. Similar lawsuits have been filed in Quebec, Ontario and British Columbia courts on behalf of purchasers of wallboard in Canada. The Canadian lawsuits also name as defendants CGC Inc., our Canadian operating subsidiary, as well as other Canadian and U.S. wallboard manufacturers.

USG has denied the allegations made in these wallboard pricing lawsuits, believes these cases are without merit, and that USG’s pricing and selling policies were and are made independently and in full compliance with the law. Class action antitrust litigation in the United States, however, is expensive, protracted, and carries the risk of triple damages and joint and several liability. To avoid the expense, risk and further distraction of management, in late 2014, we agreed to a settlement of the U.S. direct and indirect purchaser plaintiff class actions and in the third quarter of 2014, we recorded a $48 million charge for the settlements ($39.25 million for the direct purchaser settlement and $8.75 million for the indirect purchaser settlement). On August 20, 2015, the court entered final judgment orders approving both the direct and indirect purchaser settlements. No member of the direct purchaser class appealed from the final judgment order approving the direct purchaser settlement, and therefore, that settlement should be final. One person appealed from the final judgment order approving the indirect purchaser settlement, and therefore that settlement is not yet final. We believe that the appeal is without merit and that the indirect purchaser settlement order will be affirmed on appeal, but the indirect purchaser settlement will not become final unless and until the appeal is favorably resolved.

The settlement of the U.S. class action lawsuits described above does not include the Canadian lawsuits. At this stage of the Canadian lawsuits, we are not able to estimate the amount, if any, of any reasonably possible loss or range of reasonably possible losses. We believe, however, that these Canadian lawsuits will not have a material effect on our business, financial condition, operating results or cash flows.

In addition to the class action lawsuits, in the first quarter of 2015, USG and seven other wallboard manufacturers were named as defendants in a lawsuit filed in federal court in California by twelve homebuilders asserting individual claims similar to the claims asserted in the U.S. class action lawsuits. These homebuilders opted out of the class action settlements, and their lawsuit has been transferred to the United States District Court for the Eastern District of Pennsylvania that is presiding over the U.S. class action lawsuits. We believe that the cost, if any, of resolving these homebuilders’ claims will not materially increase our exposure above the $48 million agreed to in the U.S. class action settlements.

ENVIRONMENTAL LITIGATION

We have been notified by state and federal environmental protection agencies of possible involvement as one of numerous “potentially responsible parties” in a number of Superfund sites in the United States. As a potentially responsible party, we may be responsible to pay for some part of the cleanup of hazardous waste at those sites. In most of these sites, our involvement is expected to be minimal. In addition, we are involved in environmental cleanups of other property that we own or owned. As of both September 30, 2015 and December 31, 2014, we had an accrual of $16 million for our probable and reasonably estimable liability in connection with these matters. Our accruals take into account all known or estimated undiscounted costs associated with these sites, including site investigations and feasibility costs, site cleanup and remediation, certain legal costs, and fines and penalties, if any. However, we continue to review these accruals as additional information becomes available and revise them as appropriate. Based on the information known to us, we believe these environmental matters will not have a material effect on our business, financial condition, operating results or cash flows.

OTHER LITIGATION

We are named as defendants in other claims and lawsuits arising from our operations, including claims and lawsuits arising from the operation of our vehicles, product performance or warranties, personal injury and commercial disputes. We believe that we have properly accrued for our probable liability in connection with these claims and suits, taking into account the probability of liability, whether our exposure can be reasonably estimated and, if so, our estimate of our liability or the range of our liability. We do not expect these or any other litigation matters involving USG to have a material effect on our business, financial condition, operating results or cash flows.