COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
COMMITMENTS AND CONTINGENCIES
Employee severance benefits		$ 2.7
Insurance expense	$ 0.7
Cash collateral for letters of credit	$ 0.5

Liability for amount due employees, in addition to wages and any other money that employers owe employees, when their employment ends through a layoff or other termination. For example, a company may provide involuntarily terminated employees with a lump sum payment equal to one week's salary for every year of employment.

No definition available.

Name:	us-gaap_SupplementalUnemploymentBenefitsSeveranceBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant