Earnings Per Share - Details of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net loss	$ (2,177)	$ (1,952)	$ (4,558)	$ (4,832)
Dividends paid to preferred stockholders	(185)		(326)
Net loss available to common stockholders	$ (2,362)	$ (1,952)	$ (4,884)	$ (4,832)
Denominator:
Weighted average shares outstanding – basic	21,888	13,179	18,612	12,674
Weighted average shares outstanding – diluted	21,888	13,179	18,612	12,674
Shares excluded due to an exercise price greater than weighted average stock price for the period	7,100	1,973	3,930	1,869
Net loss per common share:
Basic	$ (0.11)	$ (0.15)	$ (0.26)	$ (0.38)
Diluted	$ (0.11)	$ (0.15)	$ (0.26)	$ (0.38)