Net loss per share - Additional Information (Detail)		12 Months Ended
	Feb. 27, 2014	Dec. 31, 2015 shares	Dec. 31, 2014 shares
Class of Stock [Line Items]
Conversion basis for reverse stock split		The Company effected a 1-for-19.2 reverse stock split.
Conversion ratio of reverse stock split	0.052083
Common stock outstanding		17,211,986	10,695,108
Options outstanding		865,457	824,604
Reorganization [Member]
Class of Stock [Line Items]
Common stock outstanding			5,845,260
Options outstanding			628,754
Warrants outstanding			11,363