FAIR VALUE MEASUREMENT - Schedule of fair value hierarchy of financial instruments held (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Assets:
Financial investments	$ 25.2	$ 47.6
Deferred compensation plan assets	18.4	23.4
Total assets	43.6	71.0
Liabilities:
Contingent consideration liabilities	17.5	2.2
Deferred compensation plan liabilities	18.4	23.4
Debt	868.1	867.6
Total liabilities	904.0	893.2
Level 1
Assets:
Financial investments	25.2	47.6
Deferred compensation plan assets	18.4	23.4
Total assets	43.6	71.0
Liabilities:
Deferred compensation plan liabilities	18.4	23.4
Total liabilities	18.4	23.4
Level 2
Liabilities:
Debt	868.1	867.6
Total liabilities	868.1	867.6
Level 3
Liabilities:
Contingent consideration liabilities	17.5	2.2
Total liabilities	$ 17.5	$ 2.2