Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information

The following financial information reflects all normal recurring adjustments that are, in the opinion of management, necessary for a fair statement of the results of the interim periods. Quarterly financial information for the years ended December 31, 2020 and 2019 is presented in the following table (in thousands, except per share data):

	For the Quarter Ended
	March 31		June 30		September 30		December 31
2020
Sales	$	97,926	$	109,236	$	123,603	$	168,065
Gross profit	$	50,261	$	54,390	$	65,313	$	90,556
Operating expenses	$	63,834	$	66,427	$	66,322	$	71,894
Operating income (loss)	$	(13,573)	$	(12,037)	$	(1,009)	$	18,662
Net income (loss)	$	(14,867)	$	(27,107)	$	(9,408)	$	17,000
Basic net income (loss) per share (1)	$	(0.25)	$	(0.45)	$	(0.15)	$	0.27
Diluted net income (loss) per share (1)(2)	$	(0.25)	$	(0.45)	$	(0.15)	$	0.22
2019
Sales	$	65,995	$	93,255	$	94,657	$	108,398
Gross profit	$	33,353	$	49,904	$	50,683	$	60,272
Operating expenses	$	44,350	$	51,769	$	56,687	$	58,128
Operating income (loss)	$	(10,997)	$	(1,865)	$	(6,004)	$	2,144
Net income (loss)	$	(22,992)	$	(1,512)	$	(2,901)	$	2,652
Basic net income (loss) per share (1)	$	(0.40)	$	(0.03)	$	(0.05)	$	0.04
Diluted net income (loss) per share (1)(2)	$	(0.40)	$	(0.03)	$	(0.09)	$	0.04

(1)Net income (loss) per share is computed independently for each quarter and the full year based upon the respective average shares outstanding in each period. Therefore, the sum of the quarterly per-share calculations may not equal the reported annual per share amounts.

(2)With the exception of the fourth quarter of 2020, and the third and fourth quarters of 2019, there is no difference in the weighted average shares used to compute basic and diluted net income (loss) per share. (see Note 2, ''Summary of Significant Accounting Policies'' for further details). The numerator and denominator of the basic and diluted net income (loss) per share computations are calculated as follows for the respective quarters of 2020 and 2019 where basic and diluted net income (loss) per share differ:

	For the Quarter Ended
(in thousands)	December 31, 2020		December 31, 2019		September 30, 2019
Net income (loss)	$	17,000	$	2,652	$	(2,901)
Less: change in fair value of common stock warrants	(2,819)		—		(2,321)
Net income (loss) - diluted	$	14,181	$	2,652	$	(5,222)
Weighted average shares outstanding - basic	62,249		59,219		58,801
Dilutive common share equivalents:
Warrants to purchase common stock	308		514		394
Options to purchase common stock	2,984		3,140		—
Unvested restricted stock units	133		N/A		N/A
Awards granted under the ESPP	4		11		—
Convertible senior notes (if-converted)	—		N/A		N/A
Weighted average shares - diluted	65,678		62,884		59,195