Stockholders’ Equity - Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Jul. 12, 2017
Preferred Stock
Preferred stock, shares authorized	20,000,000		20,000,000		20,000,000
Preferred stock, shares outstanding	4,569,233		4,569,233		4,569,233
Preferred Stock, par value (in dollars per share)	$ 0.0001		$ 0.0001		$ 0.0001
Conversion ratio to Common Stock	1.2226		1.2226
Preferred Stock, cumulative dividends rate (in percentage)			10.00%
Cumulative dividends for Series A Preferred Stock	$ 914	$ 914	$ 1,828	$ 1,828
Series A Preferred Stock
Preferred Stock
Preferred stock, shares outstanding	4,569,233		4,569,233
Cumulative accrued but unpaid dividends						$ 7,900
Cumulative preferred dividends (in dollars per share)	$ 0.2	$ 0.2	$ 0.2	$ 0.2