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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Revenues	$ 598.2	$ 845.8	$ 1,383.2	$ 1,675.9
Regulated Waste and Compliance Services
Disaggregation Of Revenue [Line Items]
Revenues	418.1	553.2	951.4	1,090.1
Secure Information Destruction Services
Disaggregation Of Revenue [Line Items]
Revenues	152.5	229.4	370.6	461.4
Communication and Related Services
Disaggregation Of Revenue [Line Items]
Revenues	27.6	63.2	61.2	124.4
North America
Disaggregation Of Revenue [Line Items]
Revenues	491.3	702.8	1,145.9	1,384.3
North America | Regulated Waste and Compliance Services
Disaggregation Of Revenue [Line Items]
Revenues	328.5	445.2	767.1	872.2
North America | Secure Information Destruction Services
Disaggregation Of Revenue [Line Items]
Revenues	137.4	196.6	323.4	394.7
North America | Communication and Related Services
Disaggregation Of Revenue [Line Items]
Revenues	25.4	61.0	55.4	117.4
International
Disaggregation Of Revenue [Line Items]
Revenues	106.9	143.0	237.3	291.6
International | Regulated Waste and Compliance Services
Disaggregation Of Revenue [Line Items]
Revenues	89.6	108.0	184.3	217.9
International | Secure Information Destruction Services
Disaggregation Of Revenue [Line Items]
Revenues	15.1	32.8	47.2	66.7
International | Communication and Related Services
Disaggregation Of Revenue [Line Items]
Revenues	$ 2.2	$ 2.2	$ 5.8	$ 7.0