ACCOUNTS AND OTHER RECEIVABLES - New ASU (Details) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201602Member
Trade receivables, net		$ 564.4		$ 621.8
Other current assets		973.7
Property, plant and equipment		830.8		785.7
Other assets		2,447.5
TOTAL ASSETS		4,816.4		4,663.8
Current liabilities		928.1		947.4
Long-term liabilities		2,575.8		2,416.4
Retained earnings		2,734.5		2,713.5
Other equity		(1,422.0)
TOTAL LIABILITIES AND EQUITY		$ 4,816.4		$ 4,663.8
Cumulative effect adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Trade receivables, net	$ (3.3)
Other current assets	0.0
Property, plant and equipment	0.0
Other assets	0.0
TOTAL ASSETS	(3.3)
Current liabilities	0.0
Long-term liabilities	(0.8)
Retained earnings	(2.5)
Other equity	0.0
TOTAL LIABILITIES AND EQUITY	(3.3)
Adjusted balance
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Trade receivables, net	561.1
Other current assets	973.7
Property, plant and equipment	830.8
Other assets	2,447.5
TOTAL ASSETS	4,813.1
Current liabilities	928.1
Long-term liabilities	2,575.0
Retained earnings	2,732.0
Other equity	(1,422.0)
TOTAL LIABILITIES AND EQUITY	$ 4,813.1