BASIS OF PRESENTATION - Accounting Pronouncements Recently Adopted (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
BASIS OF PRESENTATION
Cumulative effect adjustment for the adoption of new accounting principle (ASU 2016-13)	$ (2,287.0)	$ (2,858.2)	$ (1,074.0)	$ 1,214.2