Quarterly report pursuant to Section 13 or 15(d)

DEBT (Details)

v2.4.1.9
DEBT (Details) (USD $)
0 Months Ended
Apr. 24, 2014
Dec. 31, 2014
Apr. 24, 2014
Dec. 31, 2013
3.50% convertible subordinated notes        
Debt Instrument [Line Items]        
Principal amount outstanding $ 133,700,000us-gaap_DebtInstrumentCarryingAmount
/ us-gaap_DebtInstrumentAxis
= qtm_ConvertibleSubordinatedThreeAndHalfPercentNotesMember
  $ 133,700,000us-gaap_DebtInstrumentCarryingAmount
/ us-gaap_DebtInstrumentAxis
= qtm_ConvertibleSubordinatedThreeAndHalfPercentNotesMember
 
Interest per annum on the principal amount 3.50%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= qtm_ConvertibleSubordinatedThreeAndHalfPercentNotesMember
3.50%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= qtm_ConvertibleSubordinatedThreeAndHalfPercentNotesMember
3.50%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= qtm_ConvertibleSubordinatedThreeAndHalfPercentNotesMember
3.50%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= qtm_ConvertibleSubordinatedThreeAndHalfPercentNotesMember
Debt due date Nov. 15, 2015      
Wells Fargo credit agreement        
Debt Instrument [Line Items]        
Fixed charge coverage ratio 1.5qtm_LineOfCreditFacilityFixedChargeCoverageRatioRatioToApplyRepaymentCovenant
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
  1.5qtm_LineOfCreditFacilityFixedChargeCoverageRatioRatioToApplyRepaymentCovenant
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
 
Amount of liquidity to be below for covenant to be applicable 25,000,000qtm_LineOfCreditFacilityAmountOfLiquidityRequiredToApplyCovenant
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
  25,000,000qtm_LineOfCreditFacilityAmountOfLiquidityRequiredToApplyCovenant
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
 
Line of credit facility, maximum borrowing amount 75,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
  75,000,000us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
 
Line of credit facility due date Mar. 29, 2017      
Line of credit facility, frequency of commitment fee payment Quarterly      
Line of credit facility, percent commitment fee 0.375%us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
     
Line of credit facility, average liquidity when covenant is applied 15,000,000.0qtm_LineOfCreditFacilityAverageLiquidityWhenCovenantIsApplied
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
  15,000,000.0qtm_LineOfCreditFacilityAverageLiquidityWhenCovenantIsApplied
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
 
Fixed charge coverage ratio, ratio when covenant is applicable 1.2qtm_LineOfCreditFacilityFixedChargeCoverageRatioRatioWhenCovenantIsApplied
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
  1.2qtm_LineOfCreditFacilityFixedChargeCoverageRatioRatioWhenCovenantIsApplied
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
 
Amount of borrowings, if exceeded, increase the filing of compliance certificates to monthly rather than quarterly 5,000,000.0qtm_MinimumBorrowingsThatIncreaseFrequencyOfFilingComplianceCertificates
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
  5,000,000.0qtm_MinimumBorrowingsThatIncreaseFrequencyOfFilingComplianceCertificates
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
 
Amount of liquidity required to avoid mandatory field audits 20,000,000.0qtm_LineOfCreditFacilityAmountOfLiquidityRequiredToAvoidAudits
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
  20,000,000.0qtm_LineOfCreditFacilityAmountOfLiquidityRequiredToAvoidAudits
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember
 
Wells Fargo credit agreement | Letter of credit        
Debt Instrument [Line Items]        
Total letters of credit outstanding   1,000,000us-gaap_LineOfCredit
/ us-gaap_CreditFacilityAxis
= us-gaap_LetterOfCreditMember
/ qtm_LineOfCreditAgreementAxis
= qtm_WellsFargoCreditAgreementMember