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								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 655.9	$ 636.4	$ 598.2	$ 785.0	$ 799.9	$ 833.1	$ 845.8	$ 830.1	$ 2,675.5	$ 3,308.9	$ 3,485.9
Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenues									1,806.6	2,187.8	2,261.8
Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenues									745.3	901.9	911.0
Communication and Related Services
Disaggregation of Revenue [Line Items]
Revenues									123.6	219.2	313.1
North America
Disaggregation of Revenue [Line Items]
Revenues									2,189.2	2,739.9	2,843.1
North America | Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenues									1,427.6	1,762.8	1,778.5
North America | Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenues									647.3	769.5	778.6
North America | Communication and Related Services
Disaggregation of Revenue [Line Items]
Revenues									114.3	207.6	286.0
International
Disaggregation of Revenue [Line Items]
Revenues									486.3	569.0	642.8
International | Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenues									379.0	425.0	483.3
International | Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenues									98.0	132.4	132.4
International | Communication and Related Services
Disaggregation of Revenue [Line Items]
Revenues									$ 9.3	$ 11.6	$ 27.1