Litigation	3 Months Ended
Mar. 31, 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. 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 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 October 2014, we entered into settlement agreements in principle with the attorneys representing the direct and indirect purchaser plaintiff classes in the U.S. wallboard pricing lawsuits, for which USG recorded a $48 million charge in the third quarter of 2014. In February 2015, we entered into settlement agreements among the parties that memorialized the October 2014 agreements in principle. Of the $48 million settlement amount, $39.25 million is allocated to the direct purchaser class settlement fund and $8.75 million is allocated to the indirect purchaser class settlement fund. The settlement agreements, in which we deny all wrongdoing, also include releases by participating class members of USG, and its subsidiaries, affiliates, and other related parties, for all conduct concerning any of the matters alleged, or that could have been alleged, in the lawsuits for the time period prior to and including November 30, 2014. Additionally, the settlement agreements grant us the right to terminate the settlement agreements or reduce the settlement amount in the event an agreed percentage of potential class members (determined by their relevant wallboard purchases) opts out of, or elects not to participate in, the settlements. In the first quarter of 2015, the final versions of the settlement agreements were preliminarily approved by the Court presiding over the multi-district class action litigation. As a result of the Court’s preliminary approval of the class action settlements, we deposited $39.25 million in March 2015 and $8.75 million in April 2015 into settlement fund escrow accounts. In the second quarter of 2015, 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 the deadlines specified in the Court’s preliminary approval orders. Persons who opt out of the settlements are not bound by the settlements, and may separately pursue their claims. After the opt out deadlines have passed, the Court will then determine whether to enter final approval of the settlements. The hearing on final approval of the settlements is currently scheduled for July 15, 2015. Assuming the Court enters final approval of the settlements and the settlement agreements have not been terminated due to the number of opt outs exceeding the agreed percentage, USG will have paid a maximum of $48 million to resolve the currently pending U.S. direct and indirect purchaser class action cases. If we are unable to settle the U.S. wallboard class action 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. 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. The homebuilders’ 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. The filing of this lawsuit indicates that the plaintiffs intend to opt out of the class action settlements preliminarily approved by the Court. Based on the complaint, it appears that the majority of the homebuilders are asserting claims as indirect, not direct, purchasers. Indirect purchaser antitrust claims typically are resolved for less than direct purchaser claims. It also appears from the complaint that the homebuilder plaintiffs account for approximately 5% or less of total U.S. wallboard purchases during the relevant time period. We believe that the cost, if any, of resolving these homebuilders’ claims will not materially increase our exposure from the $48 million agreed to in the class action settlements. 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. 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 March 31, 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 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 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. 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 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 October 2014, we entered into settlement agreements in principle with the attorneys representing the direct and indirect purchaser plaintiff classes in the U.S. wallboard pricing lawsuits, for which USG recorded a $48 million charge in the third quarter of 2014. In February 2015, we entered into settlement agreements among the parties that memorialized the October 2014 agreements in principle. Of the $48 million settlement amount, $39.25 million is allocated to the direct purchaser class settlement fund and $8.75 million is allocated to the indirect purchaser class settlement fund. The settlement agreements, in which we deny all wrongdoing, also include releases by participating class members of USG, and its subsidiaries, affiliates, and other related parties, for all conduct concerning any of the matters alleged, or that could have been alleged, in the lawsuits for the time period prior to and including November 30, 2014. Additionally, the settlement agreements grant us the right to terminate the settlement agreements or reduce the settlement amount in the event an agreed percentage of potential class members (determined by their relevant wallboard purchases) opts out of, or elects not to participate in, the settlements.

In the first quarter of 2015, the final versions of the settlement agreements were preliminarily approved by the Court presiding over the multi-district class action litigation. As a result of the Court’s preliminary approval of the class action settlements, we deposited $39.25 million in March 2015 and $8.75 million in April 2015 into settlement fund escrow accounts. In the second quarter of 2015, 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 the deadlines specified in the Court’s preliminary approval orders. Persons who opt out of the settlements are not bound by the settlements, and may separately pursue their claims. After the opt out deadlines have passed, the Court will then determine whether to enter final approval of the settlements. The hearing on final approval of the settlements is currently scheduled for July 15, 2015. Assuming the Court enters final approval of the settlements and the settlement agreements have not been terminated due to the number of opt outs exceeding the agreed percentage, USG will have paid a maximum of $48 million to resolve the currently pending U.S. direct and indirect purchaser class action cases. If we are unable to settle the U.S. wallboard class action 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.

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. The homebuilders’ 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. The filing of this lawsuit indicates that the plaintiffs intend to opt out of the class action settlements preliminarily approved by the Court. Based on the complaint, it appears that the majority of the homebuilders are asserting claims as indirect, not direct, purchasers. Indirect purchaser antitrust claims typically are resolved for less than direct purchaser claims. It also appears from the complaint that the homebuilder plaintiffs account for approximately 5% or less of total U.S. wallboard purchases during the relevant time period. We believe that the cost, if any, of resolving these homebuilders’ claims will not materially increase our exposure from the $48 million agreed to in the class action settlements.

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.

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 March 31, 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 results of operations, financial position or cash flows.