ACQUISITION - Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 08, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill	$ 112,990		$ 90,924
Workforce Solutions Group, Inc.
Business Acquisition [Line Items]
Cash and cash equivalents		$ 957
Accounts receivable		11,991
Other current assets		59
Property and equipment		10
Goodwill		22,066
Other intangible assets		14,200
Total assets acquired		49,283
Accounts payable and accrued expenses		3,562
Accrued compensation and benefits		1,387
Long-term contingent consideration		15,000
Total liabilities assumed		19,949
Net assets acquired		$ 29,334