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, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Revenues	$ 830.1	$ 895.0
Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	591.0	599.4
Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	37.8	39.1
International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	98.6	112.5
International RCS | Others
Disaggregation Of Revenue [Line Items]
Revenues	52.7	67.8
All Other
Disaggregation Of Revenue [Line Items]
Revenues	50.0	76.2
All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	50.0	76.2
Medical Waste and Compliance Solutions
Disaggregation Of Revenue [Line Items]
Revenues	397.5	419.9
Medical Waste and Compliance Solutions | Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	283.1	292.8
Medical Waste and Compliance Solutions | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	10.1	9.8
Medical Waste and Compliance Solutions | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	62.1	65.3
Medical Waste and Compliance Solutions | International RCS | Others
Disaggregation Of Revenue [Line Items]
Revenues	42.2	52.0
Hazardous Waste Solutions
Disaggregation Of Revenue [Line Items]
Revenues	71.7	77.5
Hazardous Waste Solutions | Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	71.7	77.5
Manufacturing and Industrial Services
Disaggregation Of Revenue [Line Items]
Revenues	67.7	85.8
Manufacturing and Industrial Services | Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	54.1	58.8
Manufacturing and Industrial Services | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	5.3	5.5
Manufacturing and Industrial Services | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	1.0	8.7
Manufacturing and Industrial Services | International RCS | Others
Disaggregation Of Revenue [Line Items]
Revenues	7.3	12.8
Secure Information Destruction Services
Disaggregation Of Revenue [Line Items]
Revenues	232.0	219.9
Secure Information Destruction Services | Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	182.1	170.3
Secure Information Destruction Services | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	16.0	16.2
Secure Information Destruction Services | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	30.7	30.4
Secure Information Destruction Services | International RCS | Others
Disaggregation Of Revenue [Line Items]
Revenues	3.2	3.0
Communication Services
Disaggregation Of Revenue [Line Items]
Revenues	41.7	49.5
Communication Services | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	4.0	4.5
Communication Services | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	3.1	5.3
Communication Services | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	34.6	39.7
Expert Solutions
Disaggregation Of Revenue [Line Items]
Revenues	19.5	42.4
Expert Solutions | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	2.4	3.1
Expert Solutions | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	1.7	2.8
Expert Solutions | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	$ 15.4	$ 36.5