BALANCE SHEET INFORMATION - Schedule of Service Parts Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Finished goods	$ 15,845	$ 13,437
Component parts	4,657	5,633
Total service inventories	$ 20,502	$ 19,070

Carrying amount of completed service parts merchandise or goods expected to be sold within one year or operating cycle, if longer.

No definition available.

Name:	qtm_ServicePartsInventoriesFinishedGoods
Namespace Prefix:	qtm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant