Equity Method Investments (Details) (USD $) In Millions, unless otherwise specified			9 Months Ended		12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 USG Boral Building Products		Sep. 30, 2014 USG Boral Building Products		Feb. 27, 2014 USG Boral Building Products	Sep. 30, 2014 Other equity method investments	Dec. 31, 2013 Other equity method investments	Sep. 30, 2014 Other equity method investments Minimum	Dec. 31, 2013 Other equity method investments Minimum	Sep. 30, 2014 Other equity method investments Maximum	Dec. 31, 2013 Other equity method investments Maximum
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 739	$ 73	$ 692	[1]	$ 692	[1]	$ 676	$ 47	$ 73
Ownership Percentage			50.00%		50.00%		50.00%			33.00%	33.00%	50.00%	50.00%
Transaction costs included in equity method investment carrying value			$ 32		$ 32

[1] The carrying value of our investment in UBBP as of September 30, 2014, includes transaction costs of approximately $32 million incurred in the fourth quarter of 2013 and first nine months of 2014.