Annual report pursuant to Section 13 and 15(d)

COMMITMENTS AND CONTINGENCIES - Narrative (Details)

v2.4.1.9
COMMITMENTS AND CONTINGENCIES - Narrative (Details) (USD $)
 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2013
Operating Leases [Line Items]      
Future minimum lease payments $ 35,855,000us-gaap_OperatingLeasesFutureMinimumPaymentsDue    
Future minimum sublease rental income 5,147,000us-gaap_OperatingLeasesFutureMinimumPaymentsDueFutureMinimumSubleaseRentals    
Rent expense 7,000,000us-gaap_LeaseAndRentalExpense 10,300,000us-gaap_LeaseAndRentalExpense 11,300,000us-gaap_LeaseAndRentalExpense
Non-cancelable commitments 46,000,000us-gaap_PurchaseCommitmentRemainingMinimumAmountCommitted    
Colorado Springs campus      
Operating Leases [Line Items]      
Number of buildings 3qtm_NumberOfBuildings
/ qtm_ColoradoSpringsCampusAxis
= qtm_ColoradoSpringsCampusMember 		   
Future minimum lease payments 18,800,000us-gaap_OperatingLeasesFutureMinimumPaymentsDue
/ qtm_ColoradoSpringsCampusAxis
= qtm_ColoradoSpringsCampusMember 		   
Future minimum sublease rental income $ 4,900,000us-gaap_OperatingLeasesFutureMinimumPaymentsDueFutureMinimumSubleaseRentals
/ qtm_ColoradoSpringsCampusAxis
= qtm_ColoradoSpringsCampusMember 		   
Five Years | Colorado Springs campus      
Operating Leases [Line Items]      
Initial lease term (in years) 5 years    
Lease extension term (in years) 5 years    
Seven Years | Colorado Springs campus      
Operating Leases [Line Items]      
Initial lease term (in years) 7 years    
15 Years | Colorado Springs campus      
Operating Leases [Line Items]      
Initial lease term (in years) 15 years    
Minimum      
Operating Leases [Line Items]      
Renewal term (in years) 1 year    
Maximum      
Operating Leases [Line Items]      
Renewal term (in years) 10 years