CHARGES FOR INTEGRATION AND RESTRUCTURING - Summary of Charges (Details) $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($)
Restructuring and Related Activities [Abstract]
Termination benefits	$ 625
Acceleration of share-based compensation related to qualifying terminations (Note 18)	324
Professional services	14,314
Other integration and restructuring costs	1,903
Total integration and restructuring charges related to the Mergers	$ 17,166

Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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