RETIREMENT PLANS - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Retirement Benefits [Abstract]
Net periodic benefit costs		$ 0.5	$ 1.0	$ 1.8	$ 3.0
Service cost component		0.8	$ 1.0	2.4	$ 2.9
Estimated fair value of plan assets		34.0		34.0		$ 37.8
Defer payment and taxation, base salary, percentage (up to)	75.00%
Defer payment and taxation, bonus and other eligible cash compensation, percentage (up to)	100.00%
Deferred compensation plan, fair value of assets		$ 3.4		$ 3.4		$ 2.0