Equity Method Investments (Details) - USD ($) $ in Millions	Sep. 30, 2015		Dec. 31, 2014	Feb. 27, 2014
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 694		$ 735
USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 650		$ 689	$ 676
Ownership percentage	50.00%		50.00%	50.00%
Other equity method investments
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 44	[1]	$ 46
Other equity method investments | Minimum
Schedule of Equity Method Investments [Line Items]
Ownership percentage	33.00%		33.00%
Other equity method investments | Maximum
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%		50.00%

[1] This amount includes our investment in Knauf-USG of $37 million which as of September 30, 2015 is classified as assets held for sale and is included in other current assets.