ACQUISITION - Narrative (Details) - USD ($) $ in Thousands		9 Months Ended
	Jun. 08, 2021	Sep. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Current portion of earnout liability		$ 7,500	$ 0
Long-term contingent consideration		7,500	0
Goodwill		112,990	$ 90,924
Customer relationships
Business Acquisition [Line Items]
Other intangible assets	$ 14,200
Weighted average useful life	11 years 6 months
Workforce Solutions Group, Inc.
Business Acquisition [Line Items]
Cash consideration, gross	$ 25,000
Net working capital adjustment	1,100
Equity consideration for acquisition, value	$ 5,000
Equity consideration for acquisition (in shares)	307,730
Contingent consideration liability, term	3 years
Contingent consideration liability	$ 15,000
Current portion of earnout liability		7,500
Long-term contingent consideration		7,500
Other intangible assets	14,200
Goodwill	$ 22,066
Acquisition and integration-related costs		$ 1,000