Equity Method Investments (Details Textual) - USD ($) $ in Millions		3 Months Ended		6 Months Ended			10 Months Ended	12 Months Ended
	Feb. 27, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014		Dec. 31, 2014	Dec. 31, 2014	Oct. 31, 2013
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments							$ 515
Long-term debt		$ 2,188		$ 2,188			2,209	$ 2,209
Debt instrument interest rate			10.00%		10.00%
Present value of contingent liability for contingent consideration for equity method investment		24		24			23	23
Equity method investments		717		717			735	735
Gain on deconsolidation of subsidiaries and consolidated joint ventures		0	$ 0	0	$ 27
Gain (loss) on revaluation of retained investment on deconsolidation					$ 11
Weighted average discount rate					11.00%
Weighted average long-term growth rate					2.00%
Dividends received from equity method investments				18	$ 0
Assets held-for-sale		42		42			$ 5	$ 5
Income from equity method investments		$ 14	5	$ 22	8
USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%	50.00%		50.00%			50.00%	50.00%
Range of outcomes in contingent consideration arrangements, value, high	$ 75
Contingent consideration for first performance period	$ 25
First performance period for contingent consideration	3 years
Contingent consideration for second performance period	$ 50
Second performance period for contingent consideration	5 years
Equity method investments	$ 676	$ 673		$ 673			$ 689	$ 689
Dividends received from equity method investments				18
Undistributed earnings		36		36
Income from equity method investments		13	$ 4	21	$ 7	[1]
Knauf USG [Member]
Schedule of Equity Method Investments [Line Items]
Assets held-for-sale		36		36
Income from equity method investments								2
Boral Limited | USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Ownership percentage by joint venture partner of equity method investment	50.00%
5.875% senior notes due 2021
Schedule of Equity Method Investments [Line Items]
Long-term debt		$ 350		$ 350			$ 350	$ 350	$ 350
Debt instrument interest rate		5.875%		5.875%			5.875%	5.875%
Base purchase price
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments							$ 500
Adjustments to purchase price
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments							$ 15

[1] Operating results are presented for UBBP for the four months ended June 30, 2014.