Litigation	12 Months Ended
Dec. 31, 2014
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 purports to bring 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 purports to bring 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. In the fall of 2013, similar lawsuits were filed in Quebec and Ontario courts on behalf of purchasers of wallboard in Canada. These Canadian lawsuits also name as defendants CGC, 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 actions were at all times lawful. U.S. antitrust litigation, however, is expensive and protracted, and carries the risk of triple damages and joint and several liability. To avoid the expense, risk and further distraction of management, in October 2014, we entered into a settlement agreement in principle with the attorneys representing the direct and indirect purchaser plaintiff classes in the U.S. wallboard pricing lawsuits. In the first quarter of 2015, we executed final settlement agreements with the attorneys representing the direct and indirect purchaser plaintiff classes, and those settlement agreements will be filed with the Court for approval. If the settlements are preliminarily approved by the Court, notice of the settlements will be provided to potential class members who will be given the opportunity to participate in the settlements, or, alternatively, opt out of the settlements by a deadline specified in the Court notice. Persons who opt out of the settlements are not bound by the settlements, and may separately purse their claims. After the opt out deadline has passed, the Court will then determine whether to enter final approval of the settlements. Assuming the Court enters final approval of the settlement, USG will pay a maximum of $48 million to resolve the currently pending U.S. direct and indirect purchaser class action cases. Accordingly, we recorded a $48 million charge in the third quarter of 2014 related to these settlements. If we are unable to settle the U.S. litigation under the terms set forth in the settlement agreements, or at all, there can be no assurance that the outcome of these lawsuits will not have a material effect on our business, financial condition, operating results or cash flows. The settlement 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 results of operations, financial position, or cash flows. 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 December 31, 2014 and December 31, 2013 we had an accrual of $16 million and $18 million, respectively, 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 results of operations, financial position 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 results of operations, financial position 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 purports to bring 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 purports to bring 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.

In the fall of 2013, similar lawsuits were filed in Quebec and Ontario courts on behalf of purchasers of wallboard in Canada. These Canadian lawsuits also name as defendants CGC, 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 actions were at all times lawful. U.S. antitrust litigation, however, is expensive and protracted, and carries the risk of triple damages and joint and several liability. To avoid the expense, risk and further distraction of management, in October 2014, we entered into a settlement agreement in principle with the attorneys representing the direct and indirect purchaser plaintiff classes in the U.S. wallboard pricing lawsuits. In the first quarter of 2015, we executed final settlement agreements with the attorneys representing the direct and indirect purchaser plaintiff classes, and those settlement agreements will be filed with the Court for approval. If the settlements are preliminarily approved by the Court, notice of the settlements will be provided to potential class members who will be given the opportunity to participate in the settlements, or, alternatively, opt out of the settlements by a deadline specified in the Court notice. Persons who opt out of the settlements are not bound by the settlements, and may separately purse their claims. After the opt out deadline has passed, the Court will then determine whether to enter final approval of the settlements. Assuming the Court enters final approval of the settlement, USG will pay a maximum of $48 million to resolve the currently pending U.S. direct and indirect purchaser class action cases. Accordingly, we recorded a $48 million charge in the third quarter of 2014 related to these settlements. If we are unable to settle the U.S. litigation under the terms set forth in the settlement agreements, or at all, there can be no assurance that the outcome of these lawsuits will not have a material effect on our business, financial condition, operating results or cash flows.

The settlement 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 results of operations, financial position, or cash flows.

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 December 31, 2014 and December 31, 2013 we had an accrual of $16 million and $18 million, respectively, 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 results of operations, financial position 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 results of operations, financial position or cash flows.