STOCK BASED COMPENSATION - Stock-Based Compensation Expense Resulting from Stock Option Awards, RSUs, PSUs and ESPP (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 5.7	$ 5.9	$ 12.8	$ 11.9
Stock Options | Selling, General and Administrative Expenses
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	2.9	3.8	5.9	7.9
Restricted Stock Units (RSUs) | Selling, General and Administrative Expenses
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	1.7	1.6	3.8	3.0
Performance-Based Restricted Stock Units | Selling, General and Administrative Expenses
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	1.0	0.2	2.6	0.4
Employee Stock Purchase Plan | Selling, General and Administrative Expenses
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 0.1	$ 0.3	$ 0.5	$ 0.6