Preferred Stock - Redemption and Conversion (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 20, 2017	Dec. 31, 2017	Dec. 31, 2016
Series B and Series C convertible preferred stock
Preferred Stock
Minimum percentage of holders required for redemption request		66.67%
Maximum percentage of shares redeemable at time of request		25.00%
Maximum additional percentage of shares redeemable upon each anniversary of the request		25.00%
Maximum indebtedness that may be incurred without shareholder approval		$ 500
Series A Redeemable Convertible Preferred Stock
Preferred Stock
Original purchase price (in dollars per share)		$ 1.00	$ 1.00
Conversion price (in dollars per share)		1.00	1.00
Series B Convertible Preferred Stock
Preferred Stock
Original purchase price (in dollars per share)		1.00	1.00
Conversion price (in dollars per share)		1.00	1.00
Series C Convertible Preferred Stock
Preferred Stock
Original purchase price (in dollars per share)		2.39	2.39
Conversion price (in dollars per share)		$ 2.39	$ 2.39
Conversion of preferred stock into common stock | Common Stock
Preferred Stock
Shares issued on conversion of preferred stock	3,174,523