<?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>2.4.1.9</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>289</ContextCount>
  <ElementCount>320</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>108</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>15</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSUNAUDITED</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVELOSSUNAUDITED</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (UNAUDITED)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050 - Statement - CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/StatementCONDENSEDCONSOLIDATEDSTATEMENTOFSTOCKHOLDERSEQUITYUNAUDITED</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (UNAUDITED)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100060 - Statement - Condensed Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100070 - Disclosure - Business and Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureBusinessAndBasisOfPresentation</Role>
      <ShortName>Business and Basis of Presentation</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100080 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureAcquisitions</Role>
      <ShortName>Acquisitions</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100090 - Disclosure - Spin-Off Of Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSpinOffOfBusiness</Role>
      <ShortName>Spin-Off Of Business</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100100 - Disclosure - Goodwill</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureGoodwill</Role>
      <ShortName>Goodwill</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100110 - Disclosure - Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureIntangibleAssets</Role>
      <ShortName>Intangible Assets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100120 - Disclosure - Long-Term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureLongTermDebt</Role>
      <ShortName>Long-Term Debt</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100130 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100140 - Disclosure - Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureEquity</Role>
      <ShortName>Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100150 - Disclosure - Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureStockBasedCompensation</Role>
      <ShortName>Stock-Based Compensation</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100160 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>100170 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>100180 - Disclosure - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureRelatedPartyTransactions</Role>
      <ShortName>Related Party Transactions</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>100190 - Disclosure - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSegmentReporting</Role>
      <ShortName>Segment Reporting</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>100200 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>100210 - Disclosure - Business and Basis of Presentation (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureBusinessAndBasisOfPresentationPolicies</Role>
      <ShortName>Business and Basis of Presentation (Policies)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>100220 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureAcquisitionsTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>100230 - Disclosure - Spin-Off Of Business (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSpinOffOfBusinessTables</Role>
      <ShortName>Spin-Off Of Business (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>100240 - Disclosure - Goodwill (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureGoodwillTables</Role>
      <ShortName>Goodwill (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>100250 - Disclosure - Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureIntangibleAssetsTables</Role>
      <ShortName>Intangible Assets (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>100260 - Disclosure - Long-Term Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureLongTermDebtTables</Role>
      <ShortName>Long-Term Debt (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>100270 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureIncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>100280 - Disclosure - Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureStockBasedCompensationTables</Role>
      <ShortName>Stock-Based Compensation (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>100290 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>100300 - Disclosure - Related Party Transactions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureRelatedPartyTransactionsTables</Role>
      <ShortName>Related Party Transactions (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>100310 - Disclosure - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSegmentReportingTables</Role>
      <ShortName>Segment Reporting (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>100320 - Disclosure - Subsequent Events (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSubsequentEventsTables</Role>
      <ShortName>Subsequent Events (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>100330 - Disclosure - Business and Basis of Presentation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureBusinessAndBasisOfPresentationAdditionalInformationDetail</Role>
      <ShortName>Business and Basis of Presentation - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>100340 - Disclosure - Acquisitions (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureAcquisitionsNarrativeDetail</Role>
      <ShortName>Acquisitions (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>100350 - Disclosure - Acquisitions (Schedule of Acquisition) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureAcquisitionsScheduleOfAcquisitionDetail</Role>
      <ShortName>Acquisitions (Schedule of Acquisition) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>100370 - Disclosure - Acquisitions (Schedule of Deferred Tax Assets and Liabilities) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureAcquisitionsScheduleOfDeferredTaxAssetsAndLiabilitiesDetail</Role>
      <ShortName>Acquisitions (Schedule of Deferred Tax Assets and Liabilities) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>100380 - Disclosure - Acquisitions (Schedule of Pro-Forma Financial Information) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureAcquisitionsScheduleOfProFormaFinancialInformationDetail</Role>
      <ShortName>Acquisitions (Schedule of Pro-Forma Financial Information) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>100390 - Disclosure - Spin-Off Of Business (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSpinOffOfBusinessNarrativeDetail</Role>
      <ShortName>Spin-Off Of Business (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>100400 - Disclosure - Spin-Off Of Business (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSpinOffOfBusinessDetail</Role>
      <ShortName>Spin-Off Of Business (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>100410 - Disclosure - Goodwill (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureGoodwillNarrativeDetail</Role>
      <ShortName>Goodwill (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>100420 - Disclosure - Goodwill (Schedule Of Goodwill) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureGoodwillScheduleOfGoodwillDetail</Role>
      <ShortName>Goodwill (Schedule Of Goodwill) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>100430 - Disclosure - Intangible Assets (Schedule of Intangible Assets) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureIntangibleAssetsScheduleOfIntangibleAssetsDetail</Role>
      <ShortName>Intangible Assets (Schedule of Intangible Assets) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>100440 - Disclosure - Long-Term Debt (Summary of Long-Term Debt) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureLongTermDebtSummaryOfLongTermDebtDetail</Role>
      <ShortName>Long-Term Debt (Summary of Long-Term Debt) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>100460 - Disclosure - Long-Term Debt (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureLongTermDebtNarrativeDetail</Role>
      <ShortName>Long-Term Debt (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>100470 - Disclosure - Long-Term Debt (Schedule of Fixed-Charge Coverage Ratio) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureLongTermDebtScheduleOfFixedChargeCoverageRatioDetail</Role>
      <ShortName>Long-Term Debt (Schedule of Fixed-Charge Coverage Ratio) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>100480 - Disclosure - Income Taxes (Schedule Of Provision For Income Tax) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureIncomeTaxesScheduleOfProvisionForIncomeTaxDetail</Role>
      <ShortName>Income Taxes (Schedule Of Provision For Income Tax) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>100490 - Disclosure - Income Taxes (Income/(Loss) from Continuing Operations Before Income Tax) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureIncomeTaxesIncomeLossFromContinuingOperationsBeforeIncomeTaxDetail</Role>
      <ShortName>Income Taxes (Income/(Loss) from Continuing Operations Before Income Tax) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>100500 - Disclosure - Income Taxes (Schedule Of Reconciliation Of Income Tax Provision) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureIncomeTaxesScheduleOfReconciliationOfIncomeTaxProvisionDetail</Role>
      <ShortName>Income Taxes (Schedule Of Reconciliation Of Income Tax Provision) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>100510 - Disclosure - Equity (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureEquityNarrativeDetail</Role>
      <ShortName>Equity (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>100520 - Disclosure - Stock-Based Compensation (Summary of Stock-based Compensation Expense Liability and Equity Classified Awards Included on the Consolidated Statements of Operations) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockBasedCompensationExpenseLiabilityAndEquityClassifiedAwardsIncludedOnConsolidatedStatementsOfOperationsDetail</Role>
      <ShortName>Stock-Based Compensation (Summary of Stock-based Compensation Expense Liability and Equity Classified Awards Included on the Consolidated Statements of Operations) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>100530 - Disclosure - Stock-Based Compensation (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureStockBasedCompensationNarrativeDetail</Role>
      <ShortName>Stock-Based Compensation (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>100540 - Disclosure - Stock-Based Compensation (Summary Of Part B RSU Issuance ) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureStockBasedCompensationSummaryOfPartBRSUIssuanceDetail</Role>
      <ShortName>Stock-Based Compensation (Summary Of Part B RSU Issuance ) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>100550 - Disclosure - Fair Value Measurements (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureFairValueMeasurementsNarrativeDetail</Role>
      <ShortName>Fair Value Measurements (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>100560 - Disclosure - Fair Value Measurements (Schedule Of Financial Instruments Measured At Fair Value On A Recurring Basis) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfFinancialInstrumentsMeasuredAtFairValueOnARecurringBasisDetail</Role>
      <ShortName>Fair Value Measurements (Schedule Of Financial Instruments Measured At Fair Value On A Recurring Basis) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>100570 - Disclosure - Commitments and Contingencies (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureCommitmentsAndContingenciesNarrativeDetail</Role>
      <ShortName>Commitments and Contingencies (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>100580 - Disclosure - Related Party Transactions (Schedule of Transactions Recognized) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureRelatedPartyTransactionsScheduleOfTransactionsRecognizedDetail</Role>
      <ShortName>Related Party Transactions (Schedule of Transactions Recognized) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>100590 - Disclosure - Related Party Transactions (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureRelatedPartyTransactionsNarrativeDetail</Role>
      <ShortName>Related Party Transactions (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>100600 - Disclosure - Segment Reporting (Narrative) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSegmentReportingNarrativeDetail</Role>
      <ShortName>Segment Reporting (Narrative) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>100610 - Disclosure - Segment Reporting (Summary of Significant Financial Information) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSegmentReportingSummaryOfSignificantFinancialInformationDetail</Role>
      <ShortName>Segment Reporting (Summary of Significant Financial Information) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>100620 - Disclosure - Subsequent Events (Redemption Rights) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSubsequentEventsRedemptionRightsDetail</Role>
      <ShortName>Subsequent Events (Redemption Rights) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>100630 - Disclosure - Subsequent Events (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.zayo.com/20150331/taxonomy/role/DisclosureSubsequentEventsDetail</Role>
      <ShortName>Subsequent Events (Detail)</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 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssetsNoncurrent had a mix of decimals attribute values: -6 -5.</Log>
    <Log type="Info">Element us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 had a mix of decimals attribute values: 0 4.</Log>
    <Log type="Info">Element us-gaap_DebtInstrumentRedemptionPricePercentage had a mix of decimals attribute values: 0 4.</Log>
    <Log type="Info">Element us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed had a mix of decimals attribute values: 0 2.</Log>
    <Log type="Info">Element us-gaap_OfficersCompensation had a mix of decimals attribute values: -5 0.</Log>
    <Log type="Info">Element zayo_HypotheticalInterestRateIncrease had a mix of decimals attribute values: 3 4.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Condensed Consolidated Statements of Cash Flows' have maximum duration 273 days and at least 50 values. Shorter duration columns must have at least one fourth (12) as many values. Column 'CoreXchange [Member]
3/3/2014 - 3/4/2014
USD ($)' is shorter (1 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Condensed Consolidated Statements of Cash Flows' have maximum duration 273 days and at least 50 values. Shorter duration columns must have at least one fourth (12) as many values. Column 'Fiber Link [Member]
9/28/2013 - 10/2/2013
USD ($)' is shorter (4 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Condensed Consolidated Statements of Cash Flows' have maximum duration 273 days and at least 50 values. Shorter duration columns must have at least one fourth (12) as many values. Column 'Fiber Link [Member]
9/29/2013 - 10/2/2013
USD ($)' is shorter (3 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Condensed Consolidated Statements of Cash Flows' have maximum duration 273 days and at least 50 values. Shorter duration columns must have at least one fourth (12) as many values. Column 'Neo Telecoms [Member]
7/2/2014 - 7/3/2014
EUR (&amp;#8364;)' is shorter (1 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Condensed Consolidated Statements of Cash Flows' have maximum duration 273 days and at least 50 values. Shorter duration columns must have at least one fourth (12) as many values. Column 'Neo Telecoms [Member]
7/2/2014 - 7/3/2014
USD ($)' is shorter (1 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Condensed Consolidated Statements of Cash Flows' have maximum duration 273 days and at least 50 values. Shorter duration columns must have at least one fourth (12) as many values. Column 'Latisys Holdings [Member]
2/22/2015 - 2/23/2015
USD ($)' is shorter (1 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Condensed Consolidated Statements of Cash Flows' have maximum duration 273 days and at least 50 values. Shorter duration columns must have at least one fourth (12) as many values. Column 'Latisys Holdings [Member]
2/24/2015 - 2/25/2015
USD ($)' is shorter (1 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Condensed Consolidated Statements of Cash Flows' have maximum duration 273 days and at least 50 values. Shorter duration columns must have at least one fourth (12) as many values. Column '1/1/2014 - 3/31/2014
USD ($)' is shorter (89 days) and has only 8 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Condensed Consolidated Statements of Cash Flows' have maximum duration 273 days and at least 50 values. Shorter duration columns must have at least one fourth (12) as many values. Column '1/1/2015 - 3/31/2015
USD ($)' is shorter (89 days) and has only 8 values, so it is being removed.</Log>
    <Log type="Info">'Monetary' elements on report '100530 - Disclosure - Stock-Based Compensation (Narrative) (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 100010 - Statement - Condensed Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2014'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2014'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2013'</Log>
    <Log type="Info">Process Flow-Through: 100020 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Oct. 10, 2014'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Oct. 09, 2014'</Log>
    <Log type="Info">Process Flow-Through: 100030 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED)</Log>
    <Log type="Info">Process Flow-Through: 100040 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (UNAUDITED)</Log>
    <Log type="Info">Process Flow-Through: 100060 - Statement - Condensed Consolidated Statements of Cash Flows</Log>
    <Log type="Info">	Process Flow-Through: Removing column '9 Months Ended
Mar. 31, 2015
Latisys Holdings [Member]
USD ($)'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '9 Months Ended
Mar. 31, 2015
Neo Telecoms [Member]
USD ($)'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '9 Months Ended
Mar. 31, 2014
Fiber Link [Member]
USD ($)'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '9 Months Ended
Mar. 31, 2015
CoreXchange [Member]
USD ($)'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '9 Months Ended
Mar. 31, 2014
CoreXchange [Member]
USD ($)'</Log>
  </Logs>
  <InputFiles>
    <File>zayo-20150331.xml</File>
    <File>zayo-20150331.xsd</File>
    <File>zayo-20150331_cal.xml</File>
    <File>zayo-20150331_def.xml</File>
    <File>zayo-20150331_lab.xml</File>
    <File>zayo-20150331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
