LEASES - Supplemental Balance Sheet Information (Details) $ in Thousands	Jun. 08, 2021 location	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets		$ 8,064	$ 10,447
Operating lease liabilities - current		4,362	4,509
Operating lease liabilities - non-current		$ 12,280	$ 15,234
Weighted-average remaining lease term		3 years 6 months	4 years 1 month 6 days
Weighted average discount rate		6.38%	6.32%
Number of locations acquired | location	8
Workforce Solutions Group, Inc.
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets		$ 1,000
Operating lease liabilities - current		300
Operating lease liabilities - non-current		$ 700