SIGNIFICANT ACCOUNTING POLICIES - New Accounting Pronouncements (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 31, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements
New accounting guidance, cumulative effect			$ (43.6)	$ 1.9	$ (29.3)
Revenue Standard Adoption
New Accounting Pronouncements
New accounting guidance, cumulative effect	$ (29.3)
Accounting Standards Update 2016-16
New Accounting Pronouncements
New accounting guidance, cumulative effect		$ (43.6)