BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - CASH AND CASH EQUIVALENTS AND RESTRICTED CASH (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 1,326.0	$ 1,501.2	$ 1,004.8
Restricted cash	74.3	76.8	94.9
Total cash and cash equivalents and restricted cash	$ 1,400.3	$ 1,578.0	$ 1,099.7	$ 1,304.9