RESTRUCTURING CHARGES - Restructuring Reserve (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021 USD ($)
Total Restructuring Charges
Restructuring Reserve [Roll Forward]
Liability Balance at period start	$ 13.8
Expense, Net	13.8
Foreign Currency Translation	0.0
Cash Utilized, Net	(22.1)
Non-cash Utilized, Net	0.0
Liability Balance at period end	5.5
RGGA:
Restructuring Reserve [Roll Forward]
Expense, Net	17.2
RGGA: | Total Restructuring Charges
Restructuring Reserve [Roll Forward]
Liability Balance at period start	12.6
Expense, Net	13.8
Foreign Currency Translation	0.0
Cash Utilized, Net	(21.8)
Non-cash Utilized, Net	0.0
Liability Balance at period end	4.6
RGGA: | Employee severance and other personnel benefits
Restructuring Reserve [Roll Forward]
Liability Balance at period start	12.6
Expense, Net	3.0
Foreign Currency Translation	0.0
Cash Utilized, Net	(11.0)
Non-cash Utilized, Net	0.0
Liability Balance at period end	4.6
RGGA: | Other Costs
Restructuring Reserve [Roll Forward]
Liability Balance at period start	0.0
Expense, Net	10.8
Foreign Currency Translation	0.0
Cash Utilized, Net	(10.8)
Non-cash Utilized, Net	0.0
Liability Balance at period end	0.0
Other immaterial actions: | Total Restructuring Charges
Restructuring Reserve [Roll Forward]
Liability Balance at period start	1.2
Expense, Net	0.0
Foreign Currency Translation	0.0
Cash Utilized, Net	(0.3)
Non-cash Utilized, Net	0.0
Liability Balance at period end	0.9
Other immaterial actions: | Employee severance and other personnel benefits
Restructuring Reserve [Roll Forward]
Liability Balance at period start	1.2
Expense, Net	0.0
Foreign Currency Translation	0.0
Cash Utilized, Net	(0.3)
Non-cash Utilized, Net	0.0
Liability Balance at period end	0.9
Other immaterial actions: | Other Costs
Restructuring Reserve [Roll Forward]
Liability Balance at period start	0.0
Expense, Net	0.0
Foreign Currency Translation	0.0
Cash Utilized, Net	0.0
Non-cash Utilized, Net	0.0
Liability Balance at period end	$ 0.0