ACCOUNTING POLICIES - Narrative (Details) $ in Millions	3 Months Ended	9 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) segment	Mar. 31, 2020 USD ($)	[1]	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Property, Plant and Equipment [Line Items]
Number of reportable segments | segment		2		4
Property, plant and equipment, net		$ 412.9		$ 488.0
Property, plant and equipment, at cost		1,089.9		1,203.0
Accumulated depreciation		677.0		$ 715.0
Foreign exchange gain		3.0	$ (42.8)
Settlement of derivative contracts		$ 19.5	36.1
Revenue shift	$ 87.0
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member		us-gaap:AccountingStandardsUpdate201613Member
Decrease in retained earnings	$ 879.5	$ 929.0	875.2	$ 983.8	$ 785.3		$ 957.3	$ 941.5	$ 896.8
Revision of Prior Period, Reclassification, Adjustment
Property, Plant and Equipment [Line Items]
Foreign exchange gain			36.1
Settlement of derivative contracts			$ 36.1
Cumulative effect adjustment
Property, Plant and Equipment [Line Items]
Decrease in retained earnings				2.0
Retained Earnings | Cumulative effect adjustment
Property, Plant and Equipment [Line Items]
Decrease in retained earnings				2.0
Tooling
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net		$ 8.0		12.9
Property, plant and equipment, at cost				94.4
Accumulated depreciation				$ 81.5

[1] The number of shares of Common Stock (par value $0.01 per share) outstanding at September 30, 2020 was 101.34.