Subsequent Event	9 Months Ended
Sep. 30, 2013
Subsequent Event [Abstract]
Subsequent Events [Text Block]	Subsequent Event On October 16, 2013, we and certain of our subsidiaries entered into two share sale and subscription agreements with Boral Limited ("Boral") and certain of its subsidiaries. Pursuant to the subscription agreements and a shareholders agreement that we expect to enter into upon the consummation of the subscription agreements, USG and Boral plan to establish a joint venture (the “USG Boral Joint Venture”) to manufacture, distribute and sell certain building products, mine raw gypsum and sell natural and synthetic gypsum throughout Asia, Australasia and the Middle East (the "Territory"). The products that USG and Boral expect to manufacture and distribute through the USG Boral Joint Venture include products for wall, ceiling, floor lining and exterior systems that utilize gypsum, wallboard, mineral fiber ceiling tiles, steel grid and studs, joint compound and other products. Under the terms of the subscription agreements, we will acquire through our subsidiaries 50% of the equity interest of each of Boral Gypsum Asia Sdn Bhd (the “Boral Asia Business”) and Boral Australian Gypsum Limited (the “Boral Australia Business” and together with the Boral Asia Business, the “Boral Business”), and Boral will hold through its subsidiaries the remaining 50% of the Boral Business. We expect to fund our investment in the USG Boral Joint Venture through a $500 million cash payment to Boral, the contribution to the USG Boral Joint Venture of certain USG businesses, including our subsidiaries and joint venture investments in China, Singapore, India, Malaysia, New Zealand, Australia and the Middle East, including our joint ventures in Oman, and the grant to the USG Boral Joint Venture of a license to use certain USG intellectual property rights in the Territory. In the event certain performance targets are satisfied by the USG Boral Joint Venture, we will also pay Boral scheduled earnout payments in an aggregate amount up to $75 million. We intend to fund the cash portion of our investment in the USG Boral Joint Venture with up to $150 million of cash on hand and $350 million of long term debt. In addition, on October 16, 2013, we entered into a bridge commitment letter (the “Bridge Commitment Letter”) with Goldman Sachs Lending Partners LLC and JPMorgan Chase Bank, N.A. (collectively, the “Bridge Commitment Lenders”) and J.P. Morgan Securities LLC, pursuant to which the Bridge Commitment Lenders have committed to provide, in the event necessary, unsecured senior increasing rate bridge loans in an aggregate principal amount of $350 million on the terms and subject to the conditions set forth in the Bridge Commitment Letter. The obligation of the Bridge Commitment Lenders to provide any debt financing under the Bridge Commitment Letter is subject to certain customary conditions. The final termination date for the Bridge Commitment Letter is February 17, 2014. We will not draw any bridge loans under the facility contemplated by the Bridge Commitment Letter if we secure a sufficient amount of long-term debt financing necessary to fund the cash portion of the investment from other sources. Our investment in the USG Boral Joint Venture will be accounted for as an equity method investment and initially measured at cost. Our existing wholly owned subsidiaries and consolidated variable interest entities that will be contributed into the joint venture will be deconsolidated and any retained investment in those entities will be measured at fair value. We currently expect to close on the USG Boral Joint Venture transaction in the first quarter of 2014, with a targeted closing date of January 31, 2014. The closing of the USG Boral Joint Venture transaction is subject to certain conditions precedent, including, among other things, receipt of necessary regulatory approvals and third party consents.

Subsequent Event

On October 16, 2013, we and certain of our subsidiaries entered into two share sale and subscription agreements with Boral Limited ("Boral") and certain of its subsidiaries. Pursuant to the subscription agreements and a shareholders agreement that we expect to enter into upon the consummation of the subscription agreements, USG and Boral plan to establish a joint venture (the “USG Boral Joint Venture”) to manufacture, distribute and sell certain building products, mine raw gypsum and sell natural and synthetic gypsum throughout Asia, Australasia and the Middle East (the "Territory"). The products that USG and Boral expect to manufacture and distribute through the USG Boral Joint Venture include products for wall, ceiling, floor lining and exterior systems that utilize gypsum, wallboard, mineral fiber ceiling tiles, steel grid and studs, joint compound and other products.

Under the terms of the subscription agreements, we will acquire through our subsidiaries 50% of the equity interest of each of Boral Gypsum Asia Sdn Bhd (the “Boral Asia Business”) and Boral Australian Gypsum Limited (the “Boral Australia Business” and together with the Boral Asia Business, the “Boral Business”), and Boral will hold through its subsidiaries the remaining 50% of the Boral Business.

We expect to fund our investment in the USG Boral Joint Venture through a $500 million cash payment to Boral, the contribution to the USG Boral Joint Venture of certain USG businesses, including our subsidiaries and joint venture investments in China, Singapore, India, Malaysia, New Zealand, Australia and the Middle East, including our joint ventures in Oman, and the grant to the USG Boral Joint Venture of a license to use certain USG intellectual property rights in the Territory. In the event certain performance targets are satisfied by the USG Boral Joint Venture, we will also pay Boral scheduled earnout payments in an aggregate amount up to $75 million.

We intend to fund the cash portion of our investment in the USG Boral Joint Venture with up to $150 million of cash on hand and $350 million of long term debt. In addition, on October 16, 2013, we entered into a bridge commitment letter (the “Bridge Commitment Letter”) with Goldman Sachs Lending Partners LLC and JPMorgan Chase Bank, N.A. (collectively, the “Bridge Commitment Lenders”) and J.P. Morgan Securities LLC, pursuant to which the Bridge Commitment Lenders have committed to provide, in the event necessary, unsecured senior increasing rate bridge loans in an aggregate principal amount of $350 million on the terms and subject to the conditions set forth in the Bridge Commitment Letter. The obligation of the Bridge Commitment Lenders to provide any debt financing under the Bridge Commitment Letter is subject to certain customary conditions. The final termination date for the Bridge Commitment Letter is February 17, 2014. We will not draw any bridge loans under the facility contemplated by the Bridge Commitment Letter if we secure a sufficient amount of long-term debt financing necessary to fund the cash portion of the investment from other sources.

Our investment in the USG Boral Joint Venture will be accounted for as an equity method investment and initially measured at cost. Our existing wholly owned subsidiaries and consolidated variable interest entities that will be contributed into the joint venture will be deconsolidated and any retained investment in those entities will be measured at fair value.

We currently expect to close on the USG Boral Joint Venture transaction in the first quarter of 2014, with a targeted closing date of January 31, 2014. The closing of the USG Boral Joint Venture transaction is subject to certain conditions precedent, including, among other things, receipt of necessary regulatory approvals and third party consents.