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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 636.4	$ 833.1	$ 2,019.6	$ 2,509.0
Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenue	415.5	551.6	1,366.9	1,641.7
Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenue	187.3	222.6	557.9	684.0
Communication and Related Services
Disaggregation of Revenue [Line Items]
Revenue	33.6	58.9	94.8	183.3
North America
Disaggregation of Revenue [Line Items]
Revenue	517.1	691.9	1,663.0	2,076.2
North America | Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenue	322.5	445.6	1,089.6	1,317.8
North America | Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenue	163.4	189.7	486.8	584.4
North America | Communication and Related Services
Disaggregation of Revenue [Line Items]
Revenue	31.2	56.6	86.6	174.0
International
Disaggregation of Revenue [Line Items]
Revenue	119.3	141.2	356.6	432.8
International | Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenue	93.0	106.0	277.3	323.9
International | Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenue	23.9	32.9	71.1	99.6
International | Communication and Related Services
Disaggregation of Revenue [Line Items]
Revenue	$ 2.4	$ 2.3	$ 8.2	$ 9.3