GOODWILL AND INTANGIBLE ASSETS - Summary of Intangible Assets by Intangible Asset Type (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 38,879	$ 36,179
Less accumulated amortization	(29,164)	(28,030)
Intangible assets, net	9,715	8,149
Covenants Not-to-Compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets	19,192	18,092
Less accumulated amortization	(17,198)	(16,851)
Intangible assets, net	1,994	1,241
Client Lists
Finite-Lived Intangible Assets [Line Items]
Intangible assets	19,687	18,087
Less accumulated amortization	(11,966)	(11,179)
Intangible assets, net	$ 7,721	$ 6,908