SHARE-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Compensation Expenses Related to Share Based Compensation

The compensation expense related to the Company’s share-based compensation arrangements has been included in the condensed consolidated statements of comprehensive loss as follows (in millions):

	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Sales, general and administrative	$	6.2	$	4.2	$	11.7	$	8.3
Research and development		3.7		3.1	$	7.2	$	5.9
Total share-based compensation expense	$	9.9	$	7.3	$	18.9	$	14.2

Weighted-Average Assumptions for Stock Option Grants using Black-Scholes Option-Pricing Model

The estimated fair value of each stock option granted was determined on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions for the stock option grants:

	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Risk-free interest rate		1.9	%		1.5	%		2.0	%		1.4	%
Expected volatility of common stock		58.5	%		60.0	%		58.1	%		60.0	%
Dividend yield		0.0	%		0.0	%		0.0	%		0.0	%
Expected option term		5.6 years			5.7 years			5.7 years			5.6 years