RESTRUCTURING, DIVESTITURES AND ASSETS HELD FOR SALE - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended		30 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2018
Restructuring Cost And Reserve [Line Items]
Restructuring charges					$ 13.9
Employee termination					11.5
Non-cash impairment charges					2.4
Payments for restructuring liability		$ 2.2
Proceeds from sale of business			$ 8.2
United Kingdom
Restructuring Cost And Reserve [Line Items]
Consideration for sale of business	$ 11.5		11.5				$ 11.5
Proceeds from sale of business			8.2
Consideration from business sale held in escrow			3.3
Assets and Liabilities Held for Sale, Not Discontinued Operations | Selling, General and Administrative Expenses
Restructuring Cost And Reserve [Line Items]
Non-cash impairment charges	6.9		6.9
Assets and Liabilities Held for Sale, Not Discontinued Operations | Selling, General and Administrative Expenses | United Kingdom
Restructuring Cost And Reserve [Line Items]
Non-cash impairment charges	0.1		4.2		6.8	$ 3.8	14.8
Disposal Group, Disposed of by Sale, Not Discontinued Operations | United Kingdom
Restructuring Cost And Reserve [Line Items]
Proceeds from sale of business				$ 1.2
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Selling, General and Administrative Expenses | United Kingdom
Restructuring Cost And Reserve [Line Items]
Pre-tax loss from sale				3.6
Loss from sale, net of tax				$ 2.9
Domestic And Canada Regulated Waste And Compliance Services
Restructuring Cost And Reserve [Line Items]
Restructuring charges					5.5
International Regulated Waste And Compliance Services
Restructuring Cost And Reserve [Line Items]
Restructuring charges					3.3
Other
Restructuring Cost And Reserve [Line Items]
Restructuring charges					$ 5.1
Employee Termination Charges
Restructuring Cost And Reserve [Line Items]
Employee termination restructuring charges anticipated	20.0		20.0				20.0
Employee Termination Charges | Domestic And Canada Regulated Waste And Compliance Services
Restructuring Cost And Reserve [Line Items]
Employee termination restructuring charges anticipated	8.0		8.0				8.0
Employee Termination Charges | International Regulated Waste And Compliance Services
Restructuring Cost And Reserve [Line Items]
Employee termination restructuring charges anticipated	1.0		1.0				1.0
Employee Termination Charges | Other
Restructuring Cost And Reserve [Line Items]
Employee termination restructuring charges anticipated	$ 11.0		$ 11.0				$ 11.0