<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Version>2.4.0.8</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>225</ContextCount>
  <ElementCount>271</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>65</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - Condensed Consolidated Statements Of Earnings And Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/StatementCondensedConsolidatedStatementsOfEarningsAndComprehensiveIncome</Role>
      <ShortName>Condensed Consolidated Statements Of Earnings And Comprehensive Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00105 - Statement - Condensed Consolidated Statements Of Earnings And Comprehensive Income (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/StatementCondensedConsolidatedStatementsOfEarningsAndComprehensiveIncomeParenthetical</Role>
      <ShortName>Condensed Consolidated Statements Of Earnings And Comprehensive Income (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00200 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00205 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00300 - Statement - Condensed Consolidated Statements Of Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/StatementCondensedConsolidatedStatementsOfShareholdersEquity</Role>
      <ShortName>Condensed Consolidated Statements Of Shareholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00400 - Statement - Condensed Consolidated Statements Of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Condensed Consolidated Statements Of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10101 - Disclosure - Business And Basis Of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureBusinessAndBasisOfPresentation</Role>
      <ShortName>Business And Basis Of Presentation</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10201 - Disclosure - Segment Results</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSegmentResults</Role>
      <ShortName>Segment Results</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10301 - Disclosure - Discontinued Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDiscontinuedOperations</Role>
      <ShortName>Discontinued Operations</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10401 - Disclosure - Accounts And Notes Receivable</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureAccountsAndNotesReceivable</Role>
      <ShortName>Accounts And Notes Receivable</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10501 - Disclosure - Inventories</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureInventories</Role>
      <ShortName>Inventories</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10601 - Disclosure - Other Current Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureOtherCurrentAssets</Role>
      <ShortName>Other Current Assets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10701 - Disclosure - Equity Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureEquityInvestments</Role>
      <ShortName>Equity Investments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10801 - Disclosure - Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureIntangibleAssets</Role>
      <ShortName>Intangible Assets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>11101 - Disclosure - Severances And Related Costs</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSeverancesAndRelatedCosts</Role>
      <ShortName>Severances And Related Costs</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>11201 - Disclosure - Income Tax Expense</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureIncomeTaxExpense</Role>
      <ShortName>Income Tax Expense</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11301 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDebt</Role>
      <ShortName>Debt</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11401 - Disclosure - Pensions And Other Benefit Programs</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosurePensionsAndOtherBenefitPrograms</Role>
      <ShortName>Pensions And Other Benefit Programs</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11501 - Disclosure - Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureFinancialInstruments</Role>
      <ShortName>Financial Instruments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>11601 - Disclosure - Derivative Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDerivativeFinancialInstruments</Role>
      <ShortName>Derivative Financial Instruments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>11701 - Disclosure - Product Warranties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureProductWarranties</Role>
      <ShortName>Product Warranties</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>11901 - Disclosure - Accumulated Other Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureAccumulatedOtherComprehensiveIncome</Role>
      <ShortName>Accumulated Other Comprehensive Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>12001 - Disclosure - Litigation And Related Matters</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureLitigationAndRelatedMatters</Role>
      <ShortName>Litigation And Related Matters</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>12101 - Disclosure - Special Cash Dividend</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSpecialCashDividend</Role>
      <ShortName>Special Cash Dividend</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>12201 - Disclosure - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureEarningsPerShare</Role>
      <ShortName>Earnings Per Share</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>30203 - Disclosure - Segment Results (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSegmentResultsTables</Role>
      <ShortName>Segment Results (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>30303 - Disclosure - Discontinued Operations (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDiscontinuedOperationsTables</Role>
      <ShortName>Discontinued Operations (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>30403 - Disclosure - Accounts And Notes Receivable (Tables)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureAccountsAndNotesReceivableTables</Role>
      <ShortName>Accounts And Notes Receivable (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>30503 - Disclosure - Inventories (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureInventoriesTables</Role>
      <ShortName>Inventories (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>30603 - Disclosure - Other Current Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureOtherCurrentAssetsTables</Role>
      <ShortName>Other Current Assets (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>30703 - Disclosure - Equity Investments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureEquityInvestmentsTables</Role>
      <ShortName>Equity Investments (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>30803 - Disclosure - Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureIntangibleAssetsTables</Role>
      <ShortName>Intangible Assets (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>31203 - Disclosure - Income Tax Expense (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureIncomeTaxExpenseTables</Role>
      <ShortName>Income Tax Expense (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>31403 - Disclosure - Pensions And Other Benefit Programs (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosurePensionsAndOtherBenefitProgramsTables</Role>
      <ShortName>Pensions And Other Benefit Programs (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>31503 - Disclosure - Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureFinancialInstrumentsTables</Role>
      <ShortName>Financial Instruments (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>31603 - Disclosure - Derivative Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDerivativeFinancialInstrumentsTables</Role>
      <ShortName>Derivative Financial Instruments (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>31703 - Disclosure - Product Warranties (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureProductWarrantiesTables</Role>
      <ShortName>Product Warranties (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>31903 - Disclosure - Accumulated Other Comprehensive Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureAccumulatedOtherComprehensiveIncomeTables</Role>
      <ShortName>Accumulated Other Comprehensive Income (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>32203 - Disclosure - Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureEarningsPerShareTables</Role>
      <ShortName>Earnings Per Share (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>40101 - Disclosure - Business And Basis Of Presentation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureBusinessAndBasisOfPresentationDetails</Role>
      <ShortName>Business And Basis Of Presentation (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>40201 - Disclosure - Segment Results (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSegmentResultsNarrativeDetails</Role>
      <ShortName>Segment Results (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>40202 - Disclosure - Segment Results (Schedule Of Net Sales To External Customers) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSegmentResultsScheduleOfNetSalesToExternalCustomersDetails</Role>
      <ShortName>Segment Results (Schedule Of Net Sales To External Customers) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>40203 - Disclosure - Segment Results (Schedule Of Segment Operating Income (Loss)) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSegmentResultsScheduleOfSegmentOperatingIncomeLossDetails</Role>
      <ShortName>Segment Results (Schedule Of Segment Operating Income (Loss)) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>40204 - Disclosure - Segment Results (Reconciliation Of Total Consolidated Operating Income To Earnings Before Income Taxes) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSegmentResultsReconciliationOfTotalConsolidatedOperatingIncomeToEarningsBeforeIncomeTaxesDetails</Role>
      <ShortName>Segment Results (Reconciliation Of Total Consolidated Operating Income To Earnings Before Income Taxes) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>40205 - Disclosure - Segment Results (Reconciliation Of Total Segment Assets To Total Consolidated Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSegmentResultsReconciliationOfTotalSegmentAssetsToTotalConsolidatedAssetsDetails</Role>
      <ShortName>Segment Results (Reconciliation Of Total Segment Assets To Total Consolidated Assets) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>40301 - Disclosure - Discontinued Operations (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDiscontinuedOperationsNarrativeDetails</Role>
      <ShortName>Discontinued Operations (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>40302 - Disclosure - Discontinued Operations (Summary Of Results Of Discontinued Operations) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDiscontinuedOperationsSummaryOfResultsOfDiscontinuedOperationsDetails</Role>
      <ShortName>Discontinued Operations (Summary Of Results Of Discontinued Operations) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>40401 - Disclosure - Accounts And Notes Receivable (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureAccountsAndNotesReceivableDetails</Role>
      <ShortName>Accounts And Notes Receivable (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>40501 - Disclosure - Inventories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureInventoriesDetails</Role>
      <ShortName>Inventories (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>40601 - Disclosure - Other Current Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureOtherCurrentAssetsDetails</Role>
      <ShortName>Other Current Assets (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>40701 - Disclosure - Equity Investments (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureEquityInvestmentsNarrativeDetails</Role>
      <ShortName>Equity Investments (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>40704 - Disclosure - Equity Investments (Summary Of Investment In Joint Venture, Income Statement Data) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureEquityInvestmentsSummaryOfInvestmentInJointVentureIncomeStatementDataDetails</Role>
      <ShortName>Equity Investments (Summary Of Investment In Joint Venture, Income Statement Data) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>40802 - Disclosure - Intangible Assets (Schedule Of Intangible Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureIntangibleAssetsScheduleOfIntangibleAssetsDetails</Role>
      <ShortName>Intangible Assets (Schedule Of Intangible Assets) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>40803 - Disclosure - Intangible Assets (Schedule Of Amortization Expense) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureIntangibleAssetsScheduleOfAmortizationExpenseDetails</Role>
      <ShortName>Intangible Assets (Schedule Of Amortization Expense) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>41101 - Disclosure - Severances And Related Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSeverancesAndRelatedCostsDetails</Role>
      <ShortName>Severances And Related Costs (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>41201 - Disclosure - Income Tax Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureIncomeTaxExpenseDetails</Role>
      <ShortName>Income Tax Expense (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>41301 - Disclosure - Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDebtDetails</Role>
      <ShortName>Debt (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>41405 - Disclosure - Pensions And Other Benefit Programs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosurePensionsAndOtherBenefitProgramsDetails</Role>
      <ShortName>Pensions And Other Benefit Programs (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>41502 - Disclosure - Financial Instruments (Estimated Fair Value Of Financial Instruments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureFinancialInstrumentsEstimatedFairValueOfFinancialInstrumentsDetails</Role>
      <ShortName>Financial Instruments (Estimated Fair Value Of Financial Instruments) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>41503 - Disclosure - Financial Instruments (Summary Of Assets And Liabilities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureFinancialInstrumentsSummaryOfAssetsAndLiabilitiesDetails</Role>
      <ShortName>Financial Instruments (Summary Of Assets And Liabilities) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>41601 - Disclosure - Derivative Financial Instruments (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDerivativeFinancialInstrumentsNarrativeDetails</Role>
      <ShortName>Derivative Financial Instruments (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>41602 - Disclosure - Derivative Financial Instruments (Summary Of Interest Rate Swaps) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDerivativeFinancialInstrumentsSummaryOfInterestRateSwapsDetails</Role>
      <ShortName>Derivative Financial Instruments (Summary Of Interest Rate Swaps) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>41603 - Disclosure - Derivative Financial Instruments (Summary Of The Fair Value Of Derivative Instruments On The Consolidated Balance Sheet) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDerivativeFinancialInstrumentsSummaryOfFairValueOfDerivativeInstrumentsOnConsolidatedBalanceSheetDetails</Role>
      <ShortName>Derivative Financial Instruments (Summary Of The Fair Value Of Derivative Instruments On The Consolidated Balance Sheet) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>41604 - Disclosure - Derivative Financial Instruments (Summary Of The Amount Of (Loss) Recognized In Accumulated Other Comprehensive Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureDerivativeFinancialInstrumentsSummaryOfAmountOfLossRecognizedInAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Derivative Financial Instruments (Summary Of The Amount Of (Loss) Recognized In Accumulated Other Comprehensive Income) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>41701 - Disclosure - Product Warranties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureProductWarrantiesDetails</Role>
      <ShortName>Product Warranties (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>41901 - Disclosure - Accumulated Other Comprehensive Income (Components Of Accumulated Other Comprehensive Income (Loss)) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureAccumulatedOtherComprehensiveIncomeComponentsOfAccumulatedOtherComprehensiveIncomeLossDetails</Role>
      <ShortName>Accumulated Other Comprehensive Income (Components Of Accumulated Other Comprehensive Income (Loss)) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>41902 - Disclosure - Accumulated Other Comprehensive Income (Reclassification Out Of Accumulated Other Comprehensive Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureAccumulatedOtherComprehensiveIncomeReclassificationOutOfAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Accumulated Other Comprehensive Income (Reclassification Out Of Accumulated Other Comprehensive Income) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>42001 - Disclosure - Litigation And Related Matters (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureLitigationAndRelatedMattersDetails</Role>
      <ShortName>Litigation And Related Matters (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>42101 - Disclosure - Special Cash Dividend (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureSpecialCashDividendDetails</Role>
      <ShortName>Special Cash Dividend (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>42201 - Disclosure - Earnings Per Share (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureEarningsPerShareNarrativeDetails</Role>
      <ShortName>Earnings Per Share (Narrative) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>42202 - Disclosure - Earnings Per Share (Reconciliation Of Net Earnings To Net Earnings Attributable To Common Shares Used In Basic And Diluted Calculation) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureEarningsPerShareReconciliationOfNetEarningsToNetEarningsAttributableToCommonSharesUsedInBasicAndDilutedCalculationDetails</Role>
      <ShortName>Earnings Per Share (Reconciliation Of Net Earnings To Net Earnings Attributable To Common Shares Used In Basic And Diluted Calculation) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>42203 - Disclosure - Earnings Per Share (Reconciliation Of Basic Shares Outstanding To Diluted Shares Outstanding) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.armstrong.com/role/DisclosureEarningsPerShareReconciliationOfBasicSharesOutstandingToDilutedSharesOutstandingDetails</Role>
      <ShortName>Earnings Per Share (Reconciliation Of Basic Shares Outstanding To Diluted Shares Outstanding) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">Element awi_AntidumpingDuties had a mix of decimals attribute values: 2 4.</Log>
    <Log type="Info">Element us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity had a mix of decimals attribute values: -8 -6.</Log>
    <Log type="Info">'Monetary' elements on report '42001 - Disclosure - Litigation And Related Matters (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 00100 - Statement - Condensed Consolidated Statements Of Earnings And Comprehensive Income</Log>
    <Log type="Info">Process Flow-Through: 00105 - Statement - Condensed Consolidated Statements Of Earnings And Comprehensive Income (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 00200 - Statement - Condensed Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jun. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2012'</Log>
    <Log type="Info">Process Flow-Through: 00205 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 00400 - Statement - Condensed Consolidated Statements Of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>awi-20140630.xml</File>
    <File>awi-20140630.xsd</File>
    <File>awi-20140630_cal.xml</File>
    <File>awi-20140630_def.xml</File>
    <File>awi-20140630_lab.xml</File>
    <File>awi-20140630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
