Net Loss per Share - Calculations of Basic and Diluted Net Loss per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Numerator
Net loss	$ (4,133)	$ (3,124)
Net loss attributable to common shareholders	$ (4,133)	$ (3,124)
Denominator
Weighted average common shares outstanding - Basic and diluted	22,765,098	12,840,187
Net loss per share-basic and diluted	$ (0.18)	$ (0.24)