GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of carrying amount of goodwill (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2023 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 512,595
Acquisition of other business	9,701
Other	4,531
Ending balance	526,827
All Other
Goodwill [Roll Forward]
Beginning balance	4,779
Acquisition of other business	2,428
Other	0
Ending balance	7,207
Series of Individually Immaterial Business Acquisitions
Goodwill [Roll Forward]
Beginning balance	151,925
Ending balance	151,253
Working capital adjustments	672
Targus
Goodwill [Roll Forward]
Goodwill, period change	3,668
Capital Markets Segment | Operating Segments
Goodwill [Roll Forward]
Beginning balance	162,018
Acquisition of other business	0
Other	0
Ending balance	162,018
Wealth Management Segment | Operating Segments
Goodwill [Roll Forward]
Beginning balance	51,195
Acquisition of other business	0
Other	0
Ending balance	51,195
Auction and Liquidation Segment | Operating Segments
Goodwill [Roll Forward]
Beginning balance	1,975
Acquisition of other business	0
Other	0
Ending balance	1,975
Financial Consulting Segment | Operating Segments
Goodwill [Roll Forward]
Beginning balance	23,680
Acquisition of other business	7,273
Other	191
Ending balance	31,144
Communications Segment | Operating Segments
Goodwill [Roll Forward]
Beginning balance	193,195
Acquisition of other business	0
Other	672
Ending balance	193,867
Consumer Segment | Operating Segments
Goodwill [Roll Forward]
Beginning balance	75,753
Acquisition of other business	0
Other	3,668
Ending balance	$ 79,421