FAIR VALUE MEASUREMENT - Schedule of fair value hierarchy of financial instruments held (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Assets:
Financial investments	$ 155.6	$ 47.6
Deferred compensation plan assets	20.9	23.4
Total assets	176.5	71.0
Liabilities:
Contingent consideration liabilities	20.5	2.2
Deferred compensation plan liabilities	20.9	23.4
Debt	868.6	867.6
Total liabilities	910.0	893.2
Level 1
Assets:
Financial investments	155.6	47.6
Deferred compensation plan assets	20.9	23.4
Total assets	176.5	71.0
Liabilities:
Deferred compensation plan liabilities	20.9	23.4
Total liabilities	20.9	23.4
Level 2
Liabilities:
Debt	868.6	867.6
Total liabilities	868.6	867.6
Level 3
Liabilities:
Contingent consideration liabilities	20.5	2.2
Total liabilities	$ 20.5	$ 2.2