INCOME TAXES - UNRECOGNIZED TAX BENEFITS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net tax benefits from share-based transactions	$ 4.8	$ 3.4	$ 2.2
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Balance at beginning of the period	6.7	7.2	8.3
Additions for tax positions of prior years	1.5	0.5	2.0
Additions from unrecognized tax benefits acquired	14.4
Reductions for lapse of statute of limitations	(0.5)	(1.0)	(3.1)
Balance at the end	22.1	6.7	7.2
Interest accrued related to unrecognized tax benefits	0.4	0.2	$ 0.3
Stock options
Net tax benefits from share-based transactions	$ 2.6	$ 0.8