REVENUE 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	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Revenues	$ 883.3	$ 1,778.3
Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	604.5	1,203.9
Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	40.0	79.1
International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	108.2	220.7
International RCS | Others
Disaggregation Of Revenue [Line Items]
Revenues	63.4	131.2
All Other
Disaggregation Of Revenue [Line Items]
Revenues	67.2	143.4
All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	67.2	143.4
Medical Waste and Compliance Solutions
Disaggregation Of Revenue [Line Items]
Revenues	408.3	828.2
Medical Waste and Compliance Solutions | Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	284.3	577.1
Medical Waste and Compliance Solutions | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	9.9	19.7
Medical Waste and Compliance Solutions | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	65.0	130.3
Medical Waste and Compliance Solutions | International RCS | Others
Disaggregation Of Revenue [Line Items]
Revenues	49.1	101.1
Hazardous Waste Solutions
Disaggregation Of Revenue [Line Items]
Revenues	75.5	153.0
Hazardous Waste Solutions | Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	75.5	153.0
Manufacturing and Industrial Services
Disaggregation Of Revenue [Line Items]
Revenues	88.2	174.0
Manufacturing and Industrial Services | Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	65.1	123.9
Manufacturing and Industrial Services | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	5.7	11.2
Manufacturing and Industrial Services | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	6.2	14.9
Manufacturing and Industrial Services | International RCS | Others
Disaggregation Of Revenue [Line Items]
Revenues	11.2	24.0
Secure Information Destruction Services
Disaggregation Of Revenue [Line Items]
Revenues	230.0	449.9
Secure Information Destruction Services | Domestic and Canada RCS | United States
Disaggregation Of Revenue [Line Items]
Revenues	179.6	349.9
Secure Information Destruction Services | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	16.6	32.8
Secure Information Destruction Services | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	30.7	61.1
Secure Information Destruction Services | International RCS | Others
Disaggregation Of Revenue [Line Items]
Revenues	3.1	6.1
Communication Services
Disaggregation Of Revenue [Line Items]
Revenues	44.7	94.2
Communication Services | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	4.7	9.2
Communication Services | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	4.0	9.3
Communication Services | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	36.0	75.7
Expert Solutions
Disaggregation Of Revenue [Line Items]
Revenues	36.6	79.0
Expert Solutions | Domestic and Canada RCS | Canada
Disaggregation Of Revenue [Line Items]
Revenues	3.1	6.2
Expert Solutions | International RCS | Europe
Disaggregation Of Revenue [Line Items]
Revenues	2.3	5.1
Expert Solutions | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	$ 31.2	$ 67.7