Stockholders' Equity - Summary of Capital Structure (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Class Of Stock [Line Items]
Shares authorized	50,000,000	50,000,000
Shares issued	26,383,763	20,912,396
Treasury shares	(104,002)	(91,951)
Shares outstanding	26,279,761	20,820,445
Par value per share	$ 0.01	$ 0.01
Series A Preferred Dividends
Class Of Stock [Line Items]
Shares authorized	50,000	50,000
Shares issued	45,500	45,500
Shares outstanding	45,500	45,500
Par value per share	$ 0.01	$ 0.01
Liquidation preference per share	$ 100	$ 100
Liquidation preference amount	$ 4,550	$ 4,550
Dividend rate	Prime + 2%	Prime + 2%
Dividend rate	8.00%	8.00%
Subsequent dividend payment dates	Quarterly	Quarterly
Convertible to common stock	Yes	Yes
Conversion period	Anytime	Anytime
Conversion ratio - preferred to common	6.94008	6.94008
Series B Preferred Dividends
Class Of Stock [Line Items]
Shares authorized	115,000	115,000
Shares issued	51,076	51,076
Shares outstanding	51,076	51,076
Par value per share	$ 0.01	$ 0.01
Liquidation preference per share	$ 100	$ 100
Liquidation preference amount	$ 5,108	$ 5,108
Dividend rate	8.00%	8.00%
Subsequent dividend payment dates	Quarterly	Quarterly
Convertible to common stock	Yes	Yes
Conversion period	Anytime	Anytime
Conversion ratio - preferred to common	6.94008	6.94008

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Preferred stock to common stock conversion ratio.

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Describe the conversion features of preferred stock if preferred stock is convertible. That is, shares of preferred stock into which another convertible security was converted, or shares of preferred stock into which another class of preferred stock was converted.

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