OTHER CURRENT ASSETS & OTHER CURRENT LIABILITIES - Other Current Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Other Current Assets and Other Current Liabilities [Abstract]
Warranty accruals and project contingencies	$ 123.4	$ 168.8
Legal provisions	122.5	127.6
Value - added tax and other taxes payable	90.5	109.6
Compensation accrual	62.8	54.3
Social security liability	59.9	67.9
Provisions	25.9	53.0
Derivative liability	22.4	0.0
Accrued distributions to non-controlling interests	15.0	0.0
Current portion of accrued pension and other post-retirement benefits	6.1	6.9
Other accrued liabilities	201.0	230.2
Total other current liabilities	$ 729.5	$ 818.3