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, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 672.7	$ 598.2	$ 1,340.7	$ 1,383.2
Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenues	463.0	445.7	936.6	1,012.6
Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenues	209.7	152.5	404.1	370.6
North America
Disaggregation of Revenue [Line Items]
Revenues	542.6	491.3	1,076.3	1,145.9
North America | Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenues	362.2	353.9	729.0	822.5
North America | Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenues	180.4	137.4	347.3	323.4
International
Disaggregation of Revenue [Line Items]
Revenues	130.1	106.9	264.4	237.3
International | Regulated Waste and Compliance Services
Disaggregation of Revenue [Line Items]
Revenues	100.8	91.8	207.6	190.1
International | Secure Information Destruction Services
Disaggregation of Revenue [Line Items]
Revenues	$ 29.3	$ 15.1	$ 56.8	$ 47.2