SEGMENT REPORTING - Financial Information Concerning Company's Reportable Segments (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 895.0	$ 892.4
Gross Profit	358.5	368.7
Depreciation	30.8	29.1
Intangible amortization	31.9	29.1	$ 118.4
Adjusted EBITDA	189.3	199.5
Domestic And Canada Regulated Waste And Compliance Services
Segment Reporting Information [Line Items]
Revenues	638.5	633.7
Gross Profit	260.5	278.1
Depreciation	17.9	17.2
Intangible amortization	23.2	21.7
Adjusted EBITDA	190.0	203.7
International Regulated Waste And Compliance Services
Segment Reporting Information [Line Items]
Revenues	180.3	181.6
Gross Profit	62.8	58.5
Depreciation	7.3	7.8
Intangible amortization	6.6	5.4
Adjusted EBITDA	33.0	27.9
Other
Segment Reporting Information [Line Items]
Revenues	76.2	77.1
Gross Profit	35.2	32.1
Depreciation	5.6	4.1
Intangible amortization	2.1	2.0
Adjusted EBITDA	$ (33.7)	$ (32.1)