Equity - Preferred Stock (Details) $ / shares in Units, $ in Thousands				3 Months Ended		6 Months Ended
	Jan. 06, 2018 $ / shares shares	Mar. 08, 2017 USD ($)	Mar. 07, 2017 USD ($) $ / shares shares	Jun. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) $ / shares shares	Jun. 30, 2018 USD ($)	Dec. 31, 2018 $ / shares shares	Mar. 31, 2017 shares
Class of Stock [Line Items]
Preferred stock, shares authorized (shares) | shares				5,000,000		5,000,000		5,000,000
Preferred stock, par value (in dollars per share) | $ / shares				$ 0.001		$ 0.001		$ 0.001
Number of units issued | shares	409,091
Purchase price per unit (in usd per share) | $ / shares	$ 3.80
Deemed dividend on preferred stock				$ 145	$ 126	$ 285	$ 247
Dividend paid in-kind to preferred stockholders						171	165
2017 Private Placement
Class of Stock [Line Items]
Number of common shares authorized for purchase as a percent of conversion shares			100.00%
Warrant
Class of Stock [Line Items]
Discount on shares, preferred stock			$ 3,000
Deemed dividend on preferred stock						$ 300	200
Units | 2017 Private Placement
Class of Stock [Line Items]
Number of units issued | shares			8,000
Purchase price per unit (in usd per share) | $ / shares			$ 1,000
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (shares) | shares				8,000		8,000		8,000	8,000
Preferred stock, shares issued (shares) | shares				8,000		8,000		8,000
Dividend paid in-kind to preferred stockholders						$ 800	400
Series A Convertible Preferred Stock | 2017 Private Placement
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares			$ 1,000
Preferred stock, shares issued (shares) | shares			1
Conversion price (usd per share) | $ / shares			$ 11.6355
Proceeds from 2017 Series A Preferred Stock Offering, before deducting offering costs		$ 8,000	$ 1,300
Dividend rate, preferred stock			4.00%
Dividend rate, period of initial rate			5 years
Increased dividend rate, preferred stock			8.00%
Market yield			34.42%
Proceeds from beneficial conversion feature			$ 3,700
Deemed dividend on preferred stock						$ 100	$ 100
Ownership percentage, convertible preferred stock			70.00%
Series A Convertible Preferred Stock | 2017 Private Placement | Risk-free interest rate
Class of Stock [Line Items]
Risk-free interest rate			0.0315
Series A Convertible Preferred Stock | 2017 Private Placement | Credit spread
Class of Stock [Line Items]
Risk-free interest rate			0.3127