Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Fair Value of Options

The fair value of the stock options granted is estimated on the date of grant using a Black-Scholes option pricing model with the following weighted-average assumptions:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
Expected stock price volatility	74.2		%	73.6		%	75.2		%	74.1		%
Risk free interest rate	0.3		%	1.6		%	1.6		%	2.4		%
Expected life of options (years)(1)	5.67			5.68			5.67			5.68
Expected annual dividend per share	$	—		$	—		$	—		$	—

 ______________________________

(1) The average expected life is determined using actual historical data.

Schedule of Stock Options Activity

A summary of the Company's stock options for the nine months ended September 30, 2020 were as follows:

	Number of Shares	Weighted Average Exercise  Price		Weighted Average Remaining Years	Aggregate Intrinsic Value
	(in thousands)				(in millions)
Options outstanding, December 31, 2019	16,724	$	9.15
Granted	4,282	$	9.78
Exercised	(2,849)	$	7.03
Forfeited	(1,308)	$	10.41
Expired	(434)	$	13.33
Options outstanding, September 30, 2020	16,415	$	9.47	6.3	$	79.0
Vested and unvested expected to vest, September 30, 2020	15,492	$	9.42	6.2	$	75.4
Exercisable at September 30, 2020	10,150	$	8.94	4.9	$	54.6

Schedule of Non-Vested RSU Activity under the Plan

A summary of non-vested RSU activity under the Plan for the nine months ended September 30, 2020 is as follows:

	Number of Shares	Weighted Average Grant Date Fair Value		Weighted  Average Remaining  Years	Aggregate Intrinsic Value
	(in thousands)				(in millions)
Non-vested units as of December 31, 2019	5,792	$	11.18
Granted	4,623	$	11.14
Vested	(1,834)	$	9.17
Forfeited	(1,135)	$	11.06
Non-vested units as of September 30, 2020	7,446	$	11.68	2.4	$	103.3

Schedule of Equity Compensation Expenses

The following table summarizes information related to compensation expense recognized in the Consolidated Statements of Operations related to the equity awards:

	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2020		2019		2020		2019
Equity compensation expense recognized in:
Research and development expense	$	8,626	$	3,106	$	17,241	$	12,090
Selling, general, and administrative expense	7,282		5,737		19,671		19,432
Total equity compensation expense	$	15,908	$	8,843	$	36,912	$	31,522