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
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation Of Revenue [Line Items]
Revenues	$ 785.0	$ 830.1
North America
Disaggregation Of Revenue [Line Items]
Revenues	627.5	631.5
North America | United States
Disaggregation Of Revenue [Line Items]
Revenues	594.7	593.7
North America | Canada
Disaggregation Of Revenue [Line Items]
Revenues	32.8	37.8
International
Disaggregation Of Revenue [Line Items]
Revenues	130.4	148.6
International | Europe
Disaggregation Of Revenue [Line Items]
Revenues	97.7	98.6
International | Others
Disaggregation Of Revenue [Line Items]
Revenues	32.7	50.0
All Other
Disaggregation Of Revenue [Line Items]
Revenues	27.1	50.0
All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	27.1	50.0
Medical Waste and Compliance Solutions Services
Disaggregation Of Revenue [Line Items]
Revenues	387.7	397.5
Medical Waste and Compliance Solutions Services | North America | United States
Disaggregation Of Revenue [Line Items]
Revenues	287.8	285.2
Medical Waste and Compliance Solutions Services | North America | Canada
Disaggregation Of Revenue [Line Items]
Revenues	9.5	10.1
Medical Waste and Compliance Solutions Services | International | Europe
Disaggregation Of Revenue [Line Items]
Revenues	64.1	62.1
Medical Waste and Compliance Solutions Services | International | Others
Disaggregation Of Revenue [Line Items]
Revenues	26.3	40.1
Hazardous Waste Solutions Services
Disaggregation Of Revenue [Line Items]
Revenues	79.6	71.7
Hazardous Waste Solutions Services | North America | United States
Disaggregation Of Revenue [Line Items]
Revenues	79.6	71.7
Regulated Waste and Compliance Services
Disaggregation Of Revenue [Line Items]
Revenues	467.3	469.2
Regulated Waste and Compliance Services | North America | United States
Disaggregation Of Revenue [Line Items]
Revenues	367.4	356.9
Regulated Waste and Compliance Services | North America | Canada
Disaggregation Of Revenue [Line Items]
Revenues	9.5	10.1
Regulated Waste and Compliance Services | International | Europe
Disaggregation Of Revenue [Line Items]
Revenues	64.1	62.1
Regulated Waste and Compliance Services | International | Others
Disaggregation Of Revenue [Line Items]
Revenues	26.3	40.1
Secure Information Destruction Services
Disaggregation Of Revenue [Line Items]
Revenues	218.1	232.0
Secure Information Destruction Services | North America | United States
Disaggregation Of Revenue [Line Items]
Revenues	170.7	182.1
Secure Information Destruction Services | North America | Canada
Disaggregation Of Revenue [Line Items]
Revenues	15.3	16.0
Secure Information Destruction Services | International | Europe
Disaggregation Of Revenue [Line Items]
Revenues	29.3	30.7
Secure Information Destruction Services | International | Others
Disaggregation Of Revenue [Line Items]
Revenues	2.8	3.2
Manufacturing and Industrial Services
Disaggregation Of Revenue [Line Items]
Revenues	66.0	67.7
Manufacturing and Industrial Services | North America | United States
Disaggregation Of Revenue [Line Items]
Revenues	56.6	54.7
Manufacturing and Industrial Services | North America | Canada
Disaggregation Of Revenue [Line Items]
Revenues	5.1	5.3
Manufacturing and Industrial Services | International | Europe
Disaggregation Of Revenue [Line Items]
Revenues	0.7	1.0
Manufacturing and Industrial Services | International | Others
Disaggregation Of Revenue [Line Items]
Revenues	3.6	6.7
Communication Services
Disaggregation Of Revenue [Line Items]
Revenues	14.2	41.7
Communication Services | North America | Canada
Disaggregation Of Revenue [Line Items]
Revenues	0.1	4.0
Communication Services | International | Europe
Disaggregation Of Revenue [Line Items]
Revenues	0.3	3.1
Communication Services | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	13.8	34.6
Expert Solutions
Disaggregation Of Revenue [Line Items]
Revenues	19.4	19.5
Expert Solutions | North America | Canada
Disaggregation Of Revenue [Line Items]
Revenues	2.8	2.4
Expert Solutions | International | Europe
Disaggregation Of Revenue [Line Items]
Revenues	3.3	1.7
Expert Solutions | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	13.3	15.4
Communication Related Services
Disaggregation Of Revenue [Line Items]
Revenues	33.6	61.2
Communication Related Services | North America | Canada
Disaggregation Of Revenue [Line Items]
Revenues	2.9	6.4
Communication Related Services | International | Europe
Disaggregation Of Revenue [Line Items]
Revenues	3.6	4.8
Communication Related Services | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	$ 27.1	$ 50.0