INCOME TAXES - UNRECOGNIZED TAX BENEFITS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net tax benefits from share-based transactions	$ 3.8	$ 4.8	$ 3.4
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Balance at beginning of the period	22.1	6.7	7.2
Changes in tax positions of prior years, net		1.5	0.5
Changes in tax positions of prior years, net	(1.1)
Additions from unrecognized tax benefits acquired		14.4
Reductions for lapse of statute of limitations	(0.6)	(0.5)	(1.0)
Balance at the end	20.4	22.1	6.7
Unrecognized tax benefits that, if recognized, would impact the effective rate	4.3
Interest accrued related to unrecognized tax benefits	0.4	0.4
Stock options
Net tax benefits from share-based transactions	$ 2.2	$ 2.6	$ 0.8