Quantum Corporation Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE OF FINANCIAL INSTRUMENTS - Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Line of Credit \| Revolving Credit Agreement with PNC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Amended PNC Credit Facility	$ 5,960	$ 2,620
Level 2 fair value measurements \| Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Senior Secured Term Loan	185,208		$ 163,350
Level 2 fair value measurements \| Carrying Value \| Line of Credit \| Revolving Credit Agreement with PNC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Amended PNC Credit Facility	5,960		5,289
Level 2 fair value measurements \| Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Senior Secured Term Loan	188,471		159,054
Level 2 fair value measurements \| Fair Value \| Line of Credit \| Revolving Credit Agreement with PNC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Amended PNC Credit Facility	$ 5,812		$ 3,880