COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended			36 Months Ended
	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Apr. 30, 2020	Dec. 31, 2018
Loss Contingencies [Line Items]
Long-term Purchase Commitment, Amount	$ 32,200				$ 11,400
Long-term Purchase Commitment, Period	5 years
Restructuring Reserve		$ 655	$ 3,687
Lessee, Operating Lease, Liability, Payments, Due		34,021
Lessee, Operating Lease, Liability, Non-Cancellable, to be Paid		$ 36,151
Purchase Commitments [Abstract]
Maximum Purchase Commitment Period (in Years)		1 year
Aggregate total of non-cancelable purchase commitments		$ 12,900
Product warranty accrual [Roll Forward]
Accrual balance at beginning of year		1,095	1,337	$ 1,706
Accruals for product warranties		1,349	1,065	973
Cost of warranty claims		(1,225)	(1,307)	(1,342)
Accrual balance at end of period		1,219	1,095	1,337
Facilities-Related [Member]
Loss Contingencies [Line Items]
Restructuring Reserve		0	$ 0	$ 0		$ 318
Standby Letters of Credit [Member] | Office Space - Burlington, Massachusetts [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount		700
Standby Letters of Credit [Member] | Office Space - Other Facilities [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount		600
Standby Letters of Credit [Member] | Other Operating Obligations [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount		1,900
Operating Leases on Vacated Facilities [Member]
Loss Contingencies [Line Items]
Effect on Future Cash Flows, Amount		1,700
Aggregate obligation of vacated facilies		$ 1,700