Document And Entity Information (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Feb. 21, 2012	Jun. 30, 2011
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Entity Registrant Name	ARMSTRONG WORLD INDUSTRIES INC
Entity Central Index Key	0000007431
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		58,436,007
Entity Well-known Seasoned Issuer	Yes
Entity Public Float			$ 618
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No