Debt (Details Textual 1)			0 Months Ended	12 Months Ended							12 Months Ended		12 Months Ended			12 Months Ended		12 Months Ended		12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Oct. 22, 2014 Line of Credit	Dec. 31, 2014 Line of Credit USD ($)	Oct. 22, 2014 Line of Credit USD ($)	Oct. 21, 2014 Line of Credit USD ($)	Oct. 22, 2014 Letter of Credit USD ($)	Dec. 31, 2014 CGC Credit Facility USD USD ($)	Dec. 31, 2014 CGC Credit Facility	Dec. 31, 2014 CGC Credit Facility CAD CAD	Dec. 31, 2014 Ship Mortgage Facility USD ($)	Dec. 31, 2013 Ship Mortgage Facility USD ($)	Dec. 31, 2014 Industrial Revenue Bonds USD ($)	Dec. 31, 2013 Industrial Revenue Bonds USD ($)	Jun. 30, 2013 Oman, Rials Oman Credit Facilities	Dec. 31, 2014 United States of America, Dollars London Interbank Offered Rate (LIBOR) Oman Credit Facilities	Oct. 22, 2014 Subsidiaries Line of Credit USD ($)	Dec. 31, 2014 Zawawi Gypsum LLC Oman Credit Facilities	Jun. 30, 2013 Zawawi Gypsum LLC Oman Credit Facilities USD ($)	Dec. 31, 2014 USG-Zawawi Drywall LLC Oman Credit Facilities	Jun. 30, 2013 USG-Zawawi Drywall LLC Oman Credit Facilities USD ($)
Line of Credit Facility [Line Items]
Maximum borrowing limit					$ 450,000,000	$ 400,000,000											$ 50,000,000
Stated interest rate															4.00%
Current borrowing capacity				291,000,000			200,000,000	50,000,000
Maximum allowable borrowings					650,000,000
Minimum fixed charge coverage ratio			1.0
Percentage threshold requiring compliance			10.00%
Actual fixed charge coverage ratio				1.18
Borrowings available under credit facility				0
Applicable interest rate				2.01%					3.05%
Letters of credit outstanding				54,000,000						800,000
Maximum borrowing capacity of term loans																			10,000,000		26,000,000
Maximum capacity of overdraft and letter of credit facilities																			3,000,000		5,000,000
Basis spread on LIBOR																3.50%
Loan repayment subject to penalty if made within period of time, in years																		2 years		3 years
Current portion of long-term debt	4,000,000	63,000,000									4,000,000	4,000,000
Margin rate on LIBOR											1.65%
Effective interest rate											1.97%
Long term debt repayment period											8 years
Minimum liquidity											175,000,000
Amount of debt outstanding	$ 2,209,000,000	$ 2,355,000,000									$ 21,000,000	$ 25,000,000	$ 239,000,000	$ 239,000,000
Minimum fixed interest rate													5.50%
Maximum fixed interest rate													6.40%
Weighted average interest rate													5.875%