RECENT ACCOUNTING PRONOUNCEMENTS Adoption of ASU 2017-07 - Restatement of Prior Year Amounts (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Costs of revenue	$ 465.1	$ 422.7
General and administrative expenses	65.1	65.7
Sales and marketing expenses	43.5	43.1
Research and development expenses	24.7	22.4
Operating income	110.6	57.0	[1]
Interest and non-operating expenses, net	$ (1.8)	(2.2)
Accounting Standards Update 2017-07 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Costs of revenue		(0.8)
General and administrative expenses		(0.5)
Research and development expenses		(0.1)
Operating income		1.4
Interest and non-operating expenses, net		(1.4)
Accounting Standards Update 2017-07 [Member] | Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Costs of revenue		423.5
General and administrative expenses		66.2
Research and development expenses		22.5
Operating income		55.6
Interest and non-operating expenses, net		$ (0.8)

[1] (a)Operating income and operating margin for the three months ended March 31, 2017 has been restated to reflect the adoption of ASU 2017-07. Refer to Note 2, Recent Accounting Pronouncements for further information.