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Entity Arising From Bankruptcy Proceeding

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Percentage Of Equity Owned By Two Major Share Holders

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United States Bankruptcy Court where petition for bankruptcy was filed.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Date the plan of reorganization is approved by the bankruptcy court, in CCYY-MM-DD format.

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Business And Basis Of Presentation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		3 Months Ended
	Mar. 31, 2013	Sep. 30, 2012	Dec. 31, 2012 Asbestos PI Trust And TPG [Member]	Aug. 31, 2009 Asbestos PI Trust And TPG [Member]	Aug. 31, 2009 Minimum [Member] Asbestos PI Trust And TPG [Member]	Aug. 31, 2009 Additional Economic Interest [Member] Asbestos PI Trust And TPG [Member]
Business And Basis Of Presentation [Line Items]
Bankruptcy voluntary petition filed for relief date	Dec. 01, 2000
Bankruptcy court where petition filed	United States Bankruptcy Court for the District of Delaware
Plan of Reorganization approved date	Oct. 02, 2006
Entity arising from bankruptcy proceeding	Asbestos Personal Injury Settlement Trust ("Asbestos PI Trust")
Purchase of common stock				7,000,000		1,039,777
Sale of stock by investee			5,980,000
Holding percentage in Armstrong World Industries, Inc.					50.00%
Sale price of cabinet business		$ 27