BUSINESS COMBINATIONS - Summary of Purchase Price Paid for Acquisitions (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Allocated as follows:
Excess purchase price allocated to goodwill	$ 130,317		$ 122,605
Transfer Stations Acquisition
Purchase Price:
Cash paid for acquisitions	19,189	$ 2,664
Notes payable	0	2,400
Other non-cash consideration	0	100
Holdbacks	172	196
Total	19,361	5,360
Allocated as follows:
Current assets	1,640	0
Building	5,578	0
Equipment	4,642	2,291
Intangible assets	2,700	1,317
Other liabilities, net	(1,276)	(49)
Deferred tax liability	(1,635)	0
Fair value of assets acquired and liabilities assumed	11,649	3,559
Excess purchase price allocated to goodwill	$ 7,712	$ 1,801