Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands					12 Months Ended
	May 11, 2017	Sep. 15, 2016	Mar. 28, 2016	Jan. 25, 2016	Dec. 31, 2017	Dec. 31, 2016	Jun. 15, 2016
Class of Stock [Line Items]
Proceeds from issuance of common stock		$ 1,700	$ 1,200	$ 3,400
Payments of stock issuance costs				$ 100
Common stock issued during period (in shares)		1,388,889	666,667	2,601,789
Common stock, par value (usd per share)		$ 0.04	$ 0.04	$ 0.04	$ 0.04	$ 0.04	$ 0.04
Issuance of common stock and warrants, net of issuance costs					$ 3,414	$ 6,250
Stock repurchased during period (shares)		1,388,889			0	0
Sale of common stock, price per share (in usd per share)		$ 2.00
Common stock lock-up period during which investor cannot sell shares acquired			18 months
Amount of treasury stocks retired during period						$ 100
2017 Private Offering Warrants
Class of Stock [Line Items]
Common stock issued during period (in shares)					4,375,000
Common stock, par value (usd per share)					$ 0.04
Issuance of common stock and warrants, net of issuance costs					$ 3,400
Stock repurchased during period (shares)					2,187,500
Sale of common stock, price per share (in usd per share)					$ 1.35
Line of Credit | Seasonal Facility | 2017 Private Offering Warrants
Class of Stock [Line Items]
Exercisable period of warrants	4 years				4 years
Exercisable period of warrants after closing of private offering					6 months