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Represents the amount of annual excess cash flow used for mandatory prepayment of the debt instrument as required under the terms of the debt agreement.

No definition available.

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Represents the percentage of the annual excess cash flow required to be used for mandatory prepayment of the debt instrument.

No definition available.

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Represents the percentage of the net proceeds of certain asset sales and issuances or incurrences of nonpermitted indebtedness required to be used for mandatory prepayment of the debt instrument.

No definition available.

Name:	gms_LongTermDebtMandatoryRedemptionPercentageOfNetProceedsOfCertainAssetSalesAndIssuancesOrIncurrencesOfNonpermittedIndebtednessForMandatoryPrincipalPrepayment
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Write-off of amounts previously capitalized as debt issuance cost and unamortized debt discount (net of debt premium) that was originally recognized at the issuance of the instrument in an extinguishment of debt.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_DebtInstrumentLineItems
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Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

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