STOCK-BASED COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2019

Share-based Payment Arrangement [Abstract]

Schedule of Stock-Based Compensation Expense

Compensation expense included in the Company’s Condensed Consolidated Statements of Comprehensive Income (Loss) for all stock-based compensation arrangements was as follows: 

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Cost of sales	$	4,093	$	3,974	$	12,629	$	10,360
Research and development	14,261		14,257		43,037		43,099
Selling, general and administrative	20,819		18,815		66,097		58,802
Total stock-based compensation expense	$	39,173	$	37,046	$	121,763	$	112,261

Schedule of Stock Option Valuation Assumptions

The assumptions used to estimate the per share fair value of stock options granted during the periods presented were as follows: 

	Three Months Ended September 30,		Nine Months Ended September 30,
	2019	2018	2019	2018
Expected volatility	N/A	36.8%	37.1 – 37.4%	36.8 – 38.4%
Dividend yield	N/A	0.0%	0.0%	0.0%
Expected life (in years)	N/A	5.7	4.6 – 5.8	4.6 – 5.7
Risk-free interest rate	N/A	2.8%	2.2 – 3.0%	2.3 – 2.8%