GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of Goodwill (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) item	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Goodwill activity
Beginning balance	$ 180,424	$ 173,904
Additions from acquisitions	64,462	6,520
Ending balance	$ 244,886	$ 180,424
Assets acquired
Number of acquisitions during the period | item	2
Intangible assets acquired	$ 2,400		$ 2,500
Weighted average amortization period	4 years 6 months
2020 Acquisitions
Assets acquired
Stock issued	$ 5,000
Debt Brokerage Companies
Assets acquired
Number of acquisitions during the period | item	2
Total consideration transferred	$ 64,900
Cash consideration	43,800
Stock issued	5,000
Contingent consideration	$ 16,100
Debt Brokerage Company One
Assets acquired
Amortization period	4 years
Debt Brokerage Company Two
Assets acquired
Amortization period	5 years