ACQUISITIONS - Additional Information (Detail) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($) Entity	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Number of acquisitions | Entity	19
Net increase (decrease) in goodwill	$ 42.0	$ 46.5
Customer relationships
Business Acquisition [Line Items]
Acquired finite-lived intangible assets	$ 22.7
Customer relationships | Minimum
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, useful life	10 years
Customer relationships | Maximum
Business Acquisition [Line Items]
Acquired finite-lived intangible assets, useful life	30 years