INCOME TAXES - UNRECOGNIZED TAX BENEFITS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Balance at beginning of the period	$ 15.9	$ 20.4	$ 22.1
Changes in tax positions of prior years, net	(0.3)		(1.1)
Changes in tax positions of prior years, net		1.1
Reductions for lapse of statute of limitations	(0.5)	(0.1)	(0.6)
Revaluation of unrecognized tax benefits due to the Tax Act		(5.5)
Balance at the end	15.1	15.9	$ 20.4
Unrecognized tax benefits that, if recognized, would impact the effective rate	13.7
Interest accrued related to unrecognized tax benefits	$ 0.4	0.5
Stock options
Net tax benefits from share-based transactions		$ 2.2