RESTRUCTURING, DIVESTITURES, AND IMPAIRMENTS - Schedule of Impairments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	$ 3.4	$ 1.8	$ 15.7	$ 9.8
Cost of revenue (COR)
Restructuring Cost and Reserve [Line Items]
Operational optimization	0.0	0.9	0.0	5.7
Asset impairment charges	0.0	0.0	6.8	1.6
Selling, general and administrative expenses (SG&A)
Restructuring Cost and Reserve [Line Items]
Operational optimization	2.8	0.9	2.8	0.4
Asset impairment charges	0.6	0.0	6.1	2.1
North America
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	0.0	0.0	10.1	3.7
North America | Cost of revenue (COR)
Restructuring Cost and Reserve [Line Items]
Operational optimization	0.0	0.0	0.0	2.0
Asset impairment charges	0.0	0.0	6.1	1.3
North America | Selling, general and administrative expenses (SG&A)
Restructuring Cost and Reserve [Line Items]
Operational optimization	0.0	0.0	0.0	0.0
Asset impairment charges	0.0	0.0	4.0	0.4
International
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	3.4	1.8	5.6	6.1
International | Cost of revenue (COR)
Restructuring Cost and Reserve [Line Items]
Operational optimization	0.0	0.9	0.0	3.7
Asset impairment charges	0.0	0.0	0.7	0.3
International | Selling, general and administrative expenses (SG&A)
Restructuring Cost and Reserve [Line Items]
Operational optimization	2.8	0.9	2.8	0.4
Asset impairment charges	$ 0.6	$ 0.0	$ 2.1	$ 1.7