GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of carrying amount of goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($)
Goodwill [Roll Forward]
Beginning Balance	$ 512,595
Acquisition of other business	9,701
Other	1,701
Ending Balance	523,997
Capital Markets Segment
Goodwill [Roll Forward]
Beginning Balance	162,018
Acquisition of other business	0
Other	0
Ending Balance	162,018
Wealth Management Segment
Goodwill [Roll Forward]
Beginning Balance	51,195
Acquisition of other business	0
Other	0
Ending Balance	51,195
Auction and Liquidation Segment
Goodwill [Roll Forward]
Beginning Balance	1,975
Ending Balance	1,975
Financial Consulting Segment
Goodwill [Roll Forward]
Beginning Balance	23,680
Acquisition of other business	7,273
Other	36
Ending Balance	30,989
Communications Segment
Goodwill [Roll Forward]
Beginning Balance	193,195
Ending Balance	192,094
Consumer Segment
Goodwill [Roll Forward]
Beginning Balance	75,753
Acquisition of other business	0
Other	2,766
Ending Balance	78,519
All Other
Goodwill [Roll Forward]
Beginning Balance	4,779
Ending Balance	7,207
Auction and Liquidation segment:
Goodwill [Roll Forward]
Acquisition of other business	0
Other	0
Communications
Goodwill [Roll Forward]
Acquisition of other business	0
Other	(1,101)
Other Segments
Goodwill [Roll Forward]
Acquisition of other business	2,428
Other	$ 0