INCOME TAXES - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Tax
Beginning Balance	$ 75.9	$ 82.7
Increase based on tax positions taken in a prior year	2.8	9.1
Decrease based on tax positions taken in a prior year	(15.5)	(19.6)
Increase based on tax positions taken in the current year	6.5	11.0
Decrease resulting from the lapse of statutes of limitations	(4.8)	(7.3)
Ending Balance	64.9	75.9
Interest and Penalties
Beginning Balance	9.0	10.6
Increase based on tax positions taken in a prior year	5.4	1.5
Decrease based on tax positions taken in a prior year	(3.8)	(1.5)
Increase based on tax positions taken in the current year	0.2	0.2
Decrease resulting from the lapse of statutes of limitations	(1.0)	(1.8)
Ending Balance	9.8	9.0
Total
Beginning balance	84.9	93.3
Increase based on tax positions taken in a prior year	8.2	10.6
Decrease based on tax positions taken in a prior year	(19.3)	(21.1)
Increase based on tax positions taken in the current year	6.7	11.2
Decrease resulting from the lapse of statutes of limitations	(5.8)	(9.1)
Ending balance	$ 74.7	$ 84.9