REVENUES FROM CONTRACTS WITH CUSTOMERS - Schedule of Revenues Disaggregated by Service, Primary Geographical Regions and Timing of Revenue Recognition (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Revenues	$ 833.1	$ 854.9	$ 2,509.0	$ 2,633.2
Domestic And Canada Regulated Waste And Compliance Services
Disaggregation Of Revenue [Line Items]
Revenues	639.3	644.3	1,913.9	1,927.3
Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	600.4	606.7	1,797.3	1,810.6
Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	38.9	37.6	116.6	116.7
International Regulated Waste And Compliance Services
Disaggregation Of Revenue [Line Items]
Revenues	143.5	151.1	440.2	503.0
International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	91.6	95.7	284.1	316.4
International Regulated Waste And Compliance Services | Others
Disaggregation Of Revenue [Line Items]
Revenues	51.9	55.4	156.1	186.6
All Other
Disaggregation Of Revenue [Line Items]
Revenues	50.3	59.5	154.9	202.9
All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	50.3	59.5	154.9	202.9
Medical Waste and Compliance Solutions
Disaggregation Of Revenue [Line Items]
Revenues	390.9	394.6	1,178.7	1,222.8
Medical Waste and Compliance Solutions | Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	281.4	283.4	842.6	860.5
Medical Waste and Compliance Solutions | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	10.3	9.7	31.0	29.4
Medical Waste and Compliance Solutions | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	58.6	58.9	181.9	189.2
Medical Waste and Compliance Solutions | International Regulated Waste And Compliance Services | Others
Disaggregation Of Revenue [Line Items]
Revenues	40.6	42.6	123.2	143.7
Hazardous Waste Solutions
Disaggregation Of Revenue [Line Items]
Revenues	84.0	82.0	240.4	235.0
Hazardous Waste Solutions | Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	84.0	82.0	240.4	235.0
Regulated Waste And Compliance Services
Disaggregation Of Revenue [Line Items]
Revenues	474.9	476.6	1,419.1	1,457.8
Regulated Waste And Compliance Services | Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	365.4	365.4	1,083.0	1,095.5
Regulated Waste And Compliance Services | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	10.3	9.7	31.0	29.4
Regulated Waste And Compliance Services | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	58.6	58.9	181.9	189.2
Regulated Waste And Compliance Services | International Regulated Waste And Compliance Services | Others
Disaggregation Of Revenue [Line Items]
Revenues	40.6	42.6	123.2	143.7
Manufacturing and Industrial Services
Disaggregation Of Revenue [Line Items]
Revenues	76.7	79.1	222.6	253.1
Manufacturing and Industrial Services | Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	61.6	62.9	178.8	186.8
Manufacturing and Industrial Services | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	6.0	5.4	17.5	16.6
Manufacturing and Industrial Services | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	0.8	1.0	2.7	15.9
Manufacturing and Industrial Services | International Regulated Waste And Compliance Services | Others
Disaggregation Of Revenue [Line Items]
Revenues	8.3	9.8	23.6	33.8
Secure Information Destruction Services
Disaggregation Of Revenue [Line Items]
Revenues	222.6	227.6	684.0	677.5
Secure Information Destruction Services | Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	173.4	178.4	535.5	528.3
Secure Information Destruction Services | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	16.3	16.3	48.9	49.1
Secure Information Destruction Services | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	29.9	29.9	90.3	91.0
Secure Information Destruction Services | International Regulated Waste And Compliance Services | Others
Disaggregation Of Revenue [Line Items]
Revenues	3.0	3.0	9.3	9.1
Communication Services
Disaggregation Of Revenue [Line Items]
Revenues	38.7	44.7	119.5	138.9
Communication Services | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	4.0	3.5	11.9	12.7
Communication Services | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	0.4	4.0	3.9	13.3
Communication Services | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	34.3	37.2	103.7	112.9
Expert Solutions
Disaggregation Of Revenue [Line Items]
Revenues	20.2	26.9	63.8	105.9
Expert Solutions | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	2.3	2.7	7.3	8.9
Expert Solutions | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	1.9	1.9	5.3	7.0
Expert Solutions | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	16.0	22.3	51.2	90.0
Communication Related Services
Disaggregation Of Revenue [Line Items]
Revenues	58.9	71.6	183.3	244.8
Communication Related Services | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	6.3	6.2	19.2	21.6
Communication Related Services | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	2.3	5.9	9.2	20.3
Communication Related Services | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	$ 50.3	$ 59.5	$ 154.9	$ 202.9