Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings
Beginning Balances at Dec. 31, 2017	$ 24,968	$ 2	$ 17,580	$ 7,386
Beginning Balances, Shares at Dec. 31, 2017		16,752,171
Issuance of common stock upon exercise of stock options and vesting of early exercised options	138		138
Issuance of common stock upon exercise of stock options and vesting of early exercised options, Shares		132,348
Stock-based compensation	270		270
Net income (loss)	473			473
Ending Balances at Mar. 31, 2018	25,849	$ 2	17,988	7,859
Ending Balances, Shares at Mar. 31, 2018		16,884,519
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