SEGMENT REPORTING - Financial Information Concerning Company's Reportable Segments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 3,485.9	$ 3,580.7	$ 3,562.3
Depreciation	125.6	131.1	123.2
Intangible Amortization	130.3	118.4	129.3
Adjusted EBITDA	744.6	812.0	850.8
Total Assets	6,455.5	6,988.3	6,980.1
Domestic And Canada Regulated Waste And Compliance Services
Segment Reporting Information [Line Items]
Revenues	2,574.1	2,551.9	2,508.8
Depreciation	72.5	80.3	75.4
Intangible Amortization	96.7	87.6	95.7
Adjusted EBITDA	782.4	809.5	824.9
Total Assets	5,062.5	4,995.0	5,094.1
International Regulated Waste And Compliance Services
Segment Reporting Information [Line Items]
Revenues	655.1	707.6	751.7
Depreciation	29.7	30.9	35.1
Intangible Amortization	25.3	22.7	25.7
Adjusted EBITDA	95.6	93.7	93.1
Total Assets	1,110.4	1,333.1	1,357.1
All Other
Segment Reporting Information [Line Items]
Revenues	256.7	321.2	301.8
Depreciation	23.4	19.9	12.7
Intangible Amortization	8.3	8.1	7.9
Adjusted EBITDA	(133.4)	(91.2)	(67.2)
Total Assets	$ 282.6	$ 660.2	$ 528.9