SEGMENT REPORTING - Financial Information Concerning Company's Reportable Segments (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 845.8	$ 883.3	$ 1,675.9	$ 1,778.3
Adjusted EBITDA	137.7	190.9	274.5	380.2
Domestic And Canada Regulated Waste And Compliance Services
Segment Reporting Information [Line Items]
Revenues	645.8	644.5	1,274.6	1,283.0
Adjusted EBITDA	160.6	196.8	315.2	386.8
International Regulated Waste And Compliance Services
Segment Reporting Information [Line Items]
Revenues	145.4	171.6	296.7	351.9
Adjusted EBITDA	23.2	26.9	47.1	59.9
All Other
Segment Reporting Information [Line Items]
Revenues	54.6	67.2	104.6	143.4
Adjusted EBITDA	$ (46.1)	$ (32.8)	$ (87.8)	$ (66.5)