Summary of Significant Accounting Policies - Reconciliation of Basic and Diluted Income (Loss) per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
(Loss) income from continuing operations	$ (1,858)	$ (1,773)	$ (3,114)	$ (4,522)	$ (7,805)	$ (3,177)	$ (3,916)	$ (1,977)	$ (11,267)	$ (16,875)	$ 9,471
Loss from discontinued operations	0	0	0	0	0	0	0	(12)	0	(12)	(691)
Net (loss) income	$ (1,858)	$ (1,773)	$ (3,114)	$ (4,522)	$ (7,805)	$ (3,177)	$ (3,916)	$ (1,989)	$ (11,267)	$ (16,887)	$ 8,780
Denominator:
Basic weighted average common shares outstanding (in shares)									11,806	11,673	10,413
Potential common shares from options and warrants (in shares)									0	0	339
Diluted weighted average shares (in shares)									11,806	11,673	10,752