Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

Summary of the company's stock option activity and related information

A summary of stock option activity and related information is as follows:

	Options	Weighted Average Exercise Price			Weighted average remaining contractual term (years)	Aggregate intrinsic value (in thousands)
Outstanding at December 31, 2019	2,844,164		$	30.41	7.9	$	124,585
Granted	172,331		$	77.12
Exercised	(324,995)		$	4.67		$	18,795
Forfeited	(42,279)		$	36.03
Outstanding at June 30, 2020	2,649,221		$	36.51	7.8	$	133,806
Exercisable at June 30, 2020	1,132,084		$	13.79	6.3	$	82,906

Schedule of stock compensation recognized, before taxes

Total stock-based compensation recognized, before taxes, during the three and six months ended June 30, 2020 and 2019, is as follows:

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2020		2019		2020		2019
Cost of goods sold	$	33	$	26	$	86	$	52
Research and development	372		161		717		324
Selling, general and administrative	2,498		1,202		4,849		2,404
Total stock-based compensation	$	2,903	$	1,389	$	5,652	$	2,780

Summary of weighted average assumptions for fair value of options granted

The fair value of options granted to employees and non-employee directors during the six months ended June 30, 2020 and 2019 was estimated as of the grant date using the Black-Scholes option pricing model using the following assumptions:

	Six Months Ended
	June 30,
	2020	2019
Expected life (years)	5.50 - 6.25	5.50 - 6.25
Expected volatility	42.3 - 49.3%	47.7 - 50.6%
Risk-free interest rate	0.36 - 1.42%	1.87 - 2.63%
Dividend yield	0.0%	0.0%
Weighted average fair value	$35.10	$26.55