Name:	awi_BusinessAndBasisOfPresentationLineItems
Namespace Prefix:	awi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Disposal Group, Including Discontinued Operation, Sales Price

+ References

No definition available.

+ Details

Name:	awi_DisposalGroupIncludingDiscontinuedOperationSalesPrice
Namespace Prefix:	awi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Entity Arising From Bankruptcy Proceeding

+ References

No definition available.

+ Details

Name:	awi_EntityArisingFromBankruptcyProceeding
Namespace Prefix:	awi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage Of Equity Owned By Two Major Share Holders

+ References

No definition available.

+ Details

Name:	awi_PercentageOfEquityOwnedByTwoMajorShareHolders
Namespace Prefix:	awi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

United States Bankruptcy Court where petition for bankruptcy was filed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 852

-SubTopic 10

-Section 55

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6585303&loc=d3e56145-112766

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 90-7

-Paragraph 22, 67

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_BankruptcyProceedingsCourtWherePetitionWasFiled
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date petition for bankruptcy filed with the bankruptcy court, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_BankruptcyProceedingsDatePetitionsForBankruptcyFiled
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.29)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 30

-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

+ Details

Name:	us-gaap_CommonStockSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 852

-SubTopic 10

-Section 55

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=6585303&loc=d3e56451-112766

+ Details

Name:	us-gaap_PlanOfReorganizationDatesPlanConfirmed
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Business And Basis Of Presentation (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	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
Holding percentage in Armstrong World Industries, Inc.			60.00%
Sale price of cabinet business	$ 27