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, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 648.9	$ 636.4	$ 1,989.6	$ 2,019.6
Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenues	461.7	449.1	1,398.3	1,461.7
Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenues	187.2	187.3	591.3	557.9
North America
Disaggregation of Revenue [Line Items]
Revenues	523.9	517.1	1,600.2	1,663.0
North America | Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenues	365.4	353.7	1,094.4	1,176.2
North America | Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenues	158.5	163.4	505.8	486.8
International
Disaggregation of Revenue [Line Items]
Revenues	125.0	119.3	389.4	356.6
International | Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenues	96.3	95.4	303.9	285.5
International | Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenues	$ 28.7	$ 23.9	$ 85.5	$ 71.1