GOODWILL AND INTANGIBLE ASSETS - Summary of Intangible Assets by Intangible Asset Type (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 97,284	$ 66,113
Less accumulated amortization	(36,301)	(31,346)
Intangible assets, net	60,983	34,767
Covenants Not-to-Compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets	26,162	21,750
Less accumulated amortization	(18,575)	(17,584)
Intangible assets, net	7,587	4,166
Client Lists
Finite-Lived Intangible Assets [Line Items]
Intangible assets	71,122	44,363
Less accumulated amortization	(17,726)	(13,762)
Intangible assets, net	$ 53,396	$ 30,601