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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Revenues	$ 845.8	$ 883.3	$ 1,675.9	$ 1,778.3
Domestic And Canada Regulated Waste And Compliance Services
Disaggregation Of Revenue [Line Items]
Revenues	645.8	644.5	1,274.6	1,283.0
Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	605.9	604.5	1,196.9	1,203.9
Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	39.9	40.0	77.7	79.1
International Regulated Waste And Compliance Services
Disaggregation Of Revenue [Line Items]
Revenues	145.4	171.6	296.7	351.9
International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	93.9	108.2	192.5	220.7
International Regulated Waste And Compliance Services | Others
Disaggregation Of Revenue [Line Items]
Revenues	51.5	63.4	104.2	131.2
All Other
Disaggregation Of Revenue [Line Items]
Revenues	54.6	67.2	104.6	143.4
All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	54.6	67.2	104.6	143.4
Medical Waste and Compliance Solutions
Disaggregation Of Revenue [Line Items]
Revenues	390.3	408.3	787.8	828.2
Medical Waste and Compliance Solutions | Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	278.1	284.3	561.2	577.1
Medical Waste and Compliance Solutions | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	10.6	9.9	20.7	19.7
Medical Waste and Compliance Solutions | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	61.2	65.0	123.3	130.3
Medical Waste and Compliance Solutions | International Regulated Waste And Compliance Services | Others
Disaggregation Of Revenue [Line Items]
Revenues	40.4	49.1	82.6	101.1
Hazardous Waste Solutions
Disaggregation Of Revenue [Line Items]
Revenues	84.7	75.5	156.4	153.0
Hazardous Waste Solutions | Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	84.7	75.5	156.4	153.0
Manufacturing and Industrial Services
Disaggregation Of Revenue [Line Items]
Revenues	78.2	88.2	145.9	174.0
Manufacturing and Industrial Services | Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	63.1	65.1	117.2	123.9
Manufacturing and Industrial Services | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	6.2	5.7	11.5	11.2
Manufacturing and Industrial Services | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	0.9	6.2	1.9	14.9
Manufacturing and Industrial Services | International Regulated Waste And Compliance Services | Others
Disaggregation Of Revenue [Line Items]
Revenues	8.0	11.2	15.3	24.0
Secure Information Destruction Services
Disaggregation Of Revenue [Line Items]
Revenues	229.4	230.0	461.4	449.9
Secure Information Destruction Services | Domestic And Canada Regulated Waste And Compliance Services | United States
Disaggregation Of Revenue [Line Items]
Revenues	180.0	179.6	362.1	349.9
Secure Information Destruction Services | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	16.6	16.6	32.6	32.8
Secure Information Destruction Services | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	29.7	30.7	60.4	61.1
Secure Information Destruction Services | International Regulated Waste And Compliance Services | Others
Disaggregation Of Revenue [Line Items]
Revenues	3.1	3.1	6.3	6.1
Communication Services
Disaggregation Of Revenue [Line Items]
Revenues	39.1	44.7	80.8	94.2
Communication Services | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	3.9	4.7	7.9	9.2
Communication Services | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	0.4	4.0	3.5	9.3
Communication Services | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	34.8	36.0	69.4	75.7
Expert Solutions
Disaggregation Of Revenue [Line Items]
Revenues	24.1	36.6	43.6	79.0
Expert Solutions | Domestic And Canada Regulated Waste And Compliance Services | Canada
Disaggregation Of Revenue [Line Items]
Revenues	2.6	3.1	5.0	6.2
Expert Solutions | International Regulated Waste And Compliance Services | Europe
Disaggregation Of Revenue [Line Items]
Revenues	1.7	2.3	3.4	5.1
Expert Solutions | All Other | United States
Disaggregation Of Revenue [Line Items]
Revenues	$ 19.8	$ 31.2	$ 35.2	$ 67.7