Employee Equity-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2019

Share-based Payment Arrangement [Abstract]

Stock Option Activity

The following table summarizes option activity under all plans during the nine months ended September 30, 2019:

	Number of Shares		Weighted Average Exercise Price per Share
Options Outstanding January 1, 2019	8,090,636		$	12.22
Granted	2,883,596		14.47
Forfeited	(420,098	)	20.74
Exercised	(327,215	)	14.91
Expired	(67,574	)	23.41
Options Outstanding September 30, 2019	10,159,345		$	12.34

Inputs to Calculate Estimated Fair Value of Options Awarded

The table below summarizes the resulting weighted average inputs used to calculate the estimated fair value of options awarded during the periods shown below:

	Three Months Ended
	September 30,			September 30,
	2019			2018
Expected term (in years)	6.46			5.53
Volatility	59		%	58		%
Expected dividends	—			—
Risk free interest rates	1.47		%	2.75		%
Weighted average fair value	$	9.66		$	11.48

Stock Option Supplemental Information

The following table shows summary information for outstanding options and options that are exercisable (vested) as of September 30, 2019:

	Options Outstanding		Options Exercisable
Number of options	10,159,345		6,137,856
Weighted average remaining contractual term (in years)	6.14		4.32
Weighted average exercise price	$	12.34	$	9.03
Weighted average fair value	$	8.01	$	6.06
Aggregate intrinsic value (in thousands)	$	76,923	$	65,271

Restricted Stock Unit (RSU) Activity

The following table summarizes RSU and restricted stock award activity during the nine months ended September 30, 2019:

	Number of Shares		Weighted Average Grant Date Fair Value per Share
Outstanding January 1, 2019	76,000		$	18.70
Granted	11,000		20.32
Forfeited	(60,500	)	19.74
Vested/released	(7,000	)	19.47
Outstanding September 30, 2019	19,500		16.13

Equity-Based Compensation Expenses

Equity-based compensation expense is summarized below (in thousands):

	Three Months Ended				Nine Months Ended
	September 30,		September 30,		September 30,		September 30,
	2019		2018		2019		2018
Cost of sales	$	65	$	68	$	172	$	172
Research and development	897		1,476		3,226		3,926
Sales, general and administrative	2,169		1,921		6,011		8,378
	$	3,131	$	3,465	$	9,409	$	12,476