Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Beginning Balances at Dec. 31, 2018	$ 28,631	$ 2	$ 19,358		$ 9,271
Beginning Balances, Shares at Dec. 31, 2018		17,130,507
Issuance of common stock upon exercise of stock options and vesting of early exercised options	64		64
Issuance of common stock upon exercise of stock options and vesting of early exercised options, Shares		46,666
Issuance of common stock upon vesting of RSUs, Shares		14,200
Shares repurchased for tax withholdings on vesting of RSUs	(7)		(7)
Shares repurchased for tax withholdings on vesting of RSUs, Shares		(1,510)
Stock-based compensation	336		336
Net income (loss)	(618)				(618)
Ending Balances at Mar. 31, 2019	28,406	$ 2	19,751		8,653
Ending Balances, Shares at Mar. 31, 2019		17,189,863
Beginning Balances at Dec. 31, 2018	28,631	$ 2	19,358		9,271
Beginning Balances, Shares at Dec. 31, 2018		17,130,507
Net income (loss)	1,174
Ending Balances at Sep. 30, 2019	30,949	$ 2	20,502		10,445
Ending Balances, Shares at Sep. 30, 2019		17,369,590
Beginning Balances at Mar. 31, 2019	28,406	$ 2	19,751		8,653
Beginning Balances, Shares at Mar. 31, 2019		17,189,863
Issuance of common stock upon exercise of stock options and vesting of early exercised options	36		36
Issuance of common stock upon exercise of stock options and vesting of early exercised options, Shares		38,000
Issuance of common stock upon vesting of RSUs, Shares		31,300
Shares repurchased for tax withholdings on vesting of RSUs	(24)		(24)
Shares repurchased for tax withholdings on vesting of RSUs, Shares		(3,553)
Stock-based compensation	348		348
Net income (loss)	335				335
Ending Balances at Jun. 30, 2019	29,101	$ 2	20,111		8,988
Ending Balances, Shares at Jun. 30, 2019		17,255,610
Issuance of common stock upon exercise of stock options and vesting of early exercised options	80		80
Issuance of common stock upon exercise of stock options and vesting of early exercised options, Shares		100,015
Issuance of common stock upon vesting of RSUs, Shares		17,925
Shares repurchased for tax withholdings on vesting of RSUs	(26)		(26)
Shares repurchased for tax withholdings on vesting of RSUs, Shares		(3,960)
Stock-based compensation	337		337
Net income (loss)	1,457				1,457
Ending Balances at Sep. 30, 2019	30,949	$ 2	20,502		10,445
Ending Balances, Shares at Sep. 30, 2019		17,369,590
Beginning Balances at Dec. 31, 2019	32,380	$ 2	20,928	$ (15)	11,465
Beginning Balances, Shares at Dec. 31, 2019		17,449,572
Other comprehensive (income) loss - unrealized gain (loss) on available-for-sale debt securities	(93)			(93)
Issuance of common stock upon exercise of stock options and vesting of early exercised options	103		103
Issuance of common stock upon exercise of stock options and vesting of early exercised options, Shares		58,310
Issuance of common stock upon vesting of RSUs, Shares		21,425
Shares repurchased for tax withholdings on vesting of RSUs	(28)		(28)
Shares repurchased for tax withholdings on vesting of RSUs, Shares		(4,264)
Stock-based compensation	390		390
Net income (loss)	93				93
Ending Balances at Mar. 31, 2020	32,845	$ 2	21,393	(108)	11,558
Ending Balances, Shares at Mar. 31, 2020		17,525,043
Beginning Balances at Dec. 31, 2019	32,380	$ 2	20,928	(15)	11,465
Beginning Balances, Shares at Dec. 31, 2019		17,449,572
Net income (loss)	456
Ending Balances at Sep. 30, 2020	34,138	$ 2	22,149	66	11,921
Ending Balances, Shares at Sep. 30, 2020		17,634,015
Beginning Balances at Mar. 31, 2020	32,845	$ 2	21,393	(108)	11,558
Beginning Balances, Shares at Mar. 31, 2020		17,525,043
Other comprehensive (income) loss - unrealized gain (loss) on available-for-sale debt securities	187			187
Issuance of common stock upon exercise of stock options and vesting of early exercised options	36		36
Issuance of common stock upon exercise of stock options and vesting of early exercised options, Shares		18,996
Issuance of common stock upon vesting of RSUs, Shares		52,425
Shares repurchased for tax withholdings on vesting of RSUs	(20)		(20)
Shares repurchased for tax withholdings on vesting of RSUs, Shares		(5,081)
Stock-based compensation	379		379
Net income (loss)	389				389
Ending Balances at Jun. 30, 2020	33,816	$ 2	21,788	79	11,947
Ending Balances, Shares at Jun. 30, 2020		17,591,383
Other comprehensive (income) loss - unrealized gain (loss) on available-for-sale debt securities	(13)			(13)
Issuance of common stock upon exercise of stock options and vesting of early exercised options	20		20
Issuance of common stock upon exercise of stock options and vesting of early exercised options, Shares		18,251
Issuance of common stock upon vesting of RSUs, Shares		30,075
Shares repurchased for tax withholdings on vesting of RSUs	(26)		(26)
Shares repurchased for tax withholdings on vesting of RSUs, Shares		(5,694)
Stock-based compensation	367		367
Net income (loss)	(26)				(26)
Ending Balances at Sep. 30, 2020	$ 34,138	$ 2	$ 22,149	$ 66	$ 11,921
Ending Balances, Shares at Sep. 30, 2020		17,634,015