SIGNIFICANT ACCOUNTING POLICIES - NEW ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
	Jan. 01, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive loss, net		$ (34.5)				$ (24.9)				$ (34.5)	$ (24.9)
Retained earnings		460.0				380.5				460.0	380.5
Other income (expense), net		$ 0.7	$ 0.7	$ 0.4	$ 0.8	$ 0.5	$ 3.5	$ (1.1)	$ (0.8)	2.6	2.1	$ (2.1)
Accounting Standards Update 2018-02 | Adjustments for New Accounting Principle, Early Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive loss, net					(6.0)
Retained earnings					$ 6.0
Accounting Standards Update 2017-07 | Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other income (expense), net										$ 2.1	$ 2.1
Accounting Standards Update 2016-02 | Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset	$ 252.9
Current lease liability	54.2
Long-term lease liability	206.4
Retained earnings	$ 5.9