Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2020

Equity [Abstract]

Schedule of Shares of Common Stock Reserved for Future Issuance

The following shares of the Company’s common stock were reserved for future issuance as of March 31, 2020 (in thousands):

Shares underlying outstanding warrants	705
Shares underlying outstanding stock options	6,684
Shares authorized for future equity award grants	2,961
Shares authorized for issuance pursuant to awards granted under the ESPP	1,692
	12,042

Schedule of Assumptions Used in Black-Scholes Option-Pricing Model

The assumptions used in the Black-Scholes option-pricing model are as follows:

	Stock Options
	Three Months Ended March 31,
	2020		2019
Weighted average grant date fair value (per share)	$43.40		$32.51
Risk-free interest rate	1.1	%	2.5	%
Expected dividend yield	0.0	%	0.0	%
Expected volatility	72.5	%	71.6	%
Expected term (in years)	6.1		6.1

Summary for Allocation of Stock-Based Compensation Expense

The following table summarizes the allocation of stock-based compensation expense included in the consolidated statement of operations (in thousands):

	Three Months Ended March 31,
	2020		2019
Cost of sales	$	2,164	$	1,139
Selling, general & administrative	11,501		7,000
Research and development	2,200		1,695
Total	$	15,865	$	9,834