Liquidity and Going Concern Uncertainty (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended						9 Months Ended
	Oct. 01, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Line of Credit Facility [Line Items]
Cash		$ 1,271						$ 1,271		$ 2,007
Working capital		1,568						1,568
Net loss		640	$ 875	$ 598	$ 1,470	$ 1,689	$ 1,285	2,113	$ 4,444
Net cash used in operating activities								$ 668	$ 609
Payments of debt issuance costs		$ 255
Subsequent Event | Term Loan Facility | SVB Loan Agreement
Line of Credit Facility [Line Items]
Term loan facility	$ 5,200
Series E Preferred Stock | Subsequent Event | Series E Financing
Line of Credit Facility [Line Items]
Sale of stock, number of shares issued (in shares)	88,070
Gross proceeds from issuance of stock	$ 2,510
Purchase of additional shares	$ 1,250
Conversion price, per share (in dollars per share)	$ 2.85
Convertible preferred stock, shares issued upon conversion (in shares)	880,700