Condensed Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2017	$ 12,162	$ 48	$ 109,708	$ (97,595)	$ 1
Beginning balance, Shares at Dec. 31, 2017		9,827,129
Exercise of stock options	343	$ 3	340
Exercise of stock options, Shares		486,588
Issuance of common stock in connection with exercise of warrants, shares		16,129
Stock-based compensation	427		427
Other comprehensive income (loss)	29				29
Cumulative effect of change in accounting principle	3,025			3,025
Net income (loss)	(1,217)			(1,217)
Ending balance at Mar. 31, 2018	14,769	$ 51	110,475	(95,787)	30
Ending balance, Shares at Mar. 31, 2018		10,329,846
Beginning balance at Dec. 31, 2017	12,162	$ 48	109,708	(97,595)	1
Beginning balance, Shares at Dec. 31, 2017		9,827,129
Net income (loss)	(3,027)
Ending balance at Sep. 30, 2018	15,780	$ 54	113,458	(97,597)	(135)
Ending balance, Shares at Sep. 30, 2018		10,803,710
Beginning balance at Mar. 31, 2018	14,769	$ 51	110,475	(95,787)	30
Beginning balance, Shares at Mar. 31, 2018		10,329,846
Exercise of stock options	108		108
Exercise of stock options, Shares		66,628
Issuance of common stock in connection with exercise of warrants	989	$ 1	988
Issuance of common stock in connection with exercise of warrants, shares		272,309
Issuance of common stock from ESPP purchase	421	$ 1	420
Issuance of common stock from ESPP purchase, Shares		43,624
Issuance of common stock from RSUs vested, shares		47,312
Stock-based compensation	648		648
Other comprehensive income (loss)	(133)				(133)
Net income (loss)	(369)			(369)
Ending balance at Jun. 30, 2018	16,433	$ 53	112,639	(96,156)	(103)
Ending balance, Shares at Jun. 30, 2018		10,759,719
Exercise of stock options	72	$ 1	71
Exercise of stock options, Shares		37,822
Issuance of common stock in connection with exercise of warrants, shares		6,169
Stock-based compensation	748		748
Other comprehensive income (loss)	(32)				(32)
Net income (loss)	(1,441)			(1,441)
Ending balance at Sep. 30, 2018	15,780	$ 54	113,458	(97,597)	(135)
Ending balance, Shares at Sep. 30, 2018		10,803,710
Beginning balance at Dec. 31, 2018	17,147	$ 55	114,618	(97,377)	(149)
Beginning balance, Shares at Dec. 31, 2018		10,864,722
Exercise of stock options	219	$ 1	218
Exercise of stock options, Shares		177,408
Issuance of common stock upon secondary offering, net of costs	10,554	$ 1	10,553
Issuance of common stock upon secondary offering net of costs, Shares		250,000
Issuance of common stock from RSUs vested, shares		28,790
Stock-based compensation	754		754
Other comprehensive income (loss)	(13)				(13)
Net income (loss)	(362)			(362)
Ending balance at Mar. 31, 2019	28,299	$ 57	126,143	(97,739)	(162)
Ending balance, Shares at Mar. 31, 2019		11,320,920
Beginning balance at Dec. 31, 2018	$ 17,147	$ 55	114,618	(97,377)	(149)
Beginning balance, Shares at Dec. 31, 2018		10,864,722
Repurchase of common stock, Shares	0
Ending balance at Jun. 30, 2019	$ 30,448	$ 57	127,870	(97,352)	(127)
Ending balance, Shares at Jun. 30, 2019		11,476,685
Beginning balance at Dec. 31, 2018	17,147	$ 55	114,618	(97,377)	(149)
Beginning balance, Shares at Dec. 31, 2018		10,864,722
Net income (loss)	471
Ending balance at Sep. 30, 2019	28,168	$ 57	125,235	(96,906)	(218)
Ending balance, Shares at Sep. 30, 2019		11,432,178
Beginning balance at Mar. 31, 2019	28,299	$ 57	126,143	(97,739)	(162)
Beginning balance, Shares at Mar. 31, 2019		11,320,920
Exercise of stock options	129		129
Exercise of stock options, Shares		65,960
Issuance of common stock in connection with exercise of warrants	51		51
Issuance of common stock in connection with exercise of warrants, shares		12,225
Issuance of common stock from ESPP purchase	642		642
Issuance of common stock from ESPP purchase, Shares		53,508
Issuance of common stock from RSUs vested, shares		24,072
Stock-based compensation	905		905
Other comprehensive income (loss)	35				35
Net income (loss)	387			387
Ending balance at Jun. 30, 2019	30,448	$ 57	127,870	(97,352)	(127)
Ending balance, Shares at Jun. 30, 2019		11,476,685
Exercise of stock options	95	$ 1	94
Exercise of stock options, Shares		58,806
Repurchase of common stock	$ (3,466)	$ (1)	(3,465)
Repurchase of common stock, Shares	(120,000)	(120,000)
Issuance of common stock in connection with exercise of warrants	$ 20		20
Issuance of common stock in connection with exercise of warrants, shares		13,873
Issuance of common stock from RSUs vested, shares		2,814
Stock-based compensation	716		716
Other comprehensive income (loss)	(91)				(91)
Net income (loss)	446			446
Ending balance at Sep. 30, 2019	$ 28,168	$ 57	$ 125,235	$ (96,906)	$ (218)
Ending balance, Shares at Sep. 30, 2019		11,432,178