Loss per Share - Two Class Method (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Loss per Share
Net loss	$ (183)	$ (2,821)	$ (6,593)	$ (12,907)
Less: Preferred dividends	1,382	1,314	4,099	3,445
Net loss attributable to stockholders	(1,565)	(4,135)	(10,692)	(16,352)
Net loss attributable to common stockholders	$ (1,565)	$ (4,135)	$ (10,692)	$ (16,352)
Denominator:
Weighted average common shares outstanding (in shares)	13,322	12,953	13,306	12,222
(Loss) earnings per common share - basic and diluted under two class method (in dollars per share)	$ (0.12)	$ (0.32)	$ (0.80)	$ (1.34)