RESTRUCTURING, DIVESTITURES, AND IMPAIRMENTS - Schedule of Impairments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	$ 0.0	$ 8.3	$ 0.0	$ 12.3
Cost of revenue (COR)
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	0.0	6.8	0.0	6.8
Selling, general and administrative expenses (SG&A)
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	0.0	1.5	0.0	5.5
North America
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	0.0	6.2	0.0	10.2
North America | Cost of revenue (COR)
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	0.0	6.1	0.0	6.1
North America | Selling, general and administrative expenses (SG&A)
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	0.0	0.1	0.0	4.1
International
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	0.0	2.1	0.0	2.1
International | Cost of revenue (COR)
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	0.0	0.7	0.0	0.7
International | Selling, general and administrative expenses (SG&A)
Restructuring Cost and Reserve [Line Items]
Asset impairment charges	$ 0.0	$ 1.4	$ 0.0	$ 1.4