Equity - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation cost	$ 4,000,000
Unrecognized share-based compensation expense, weighted-average recognition period	1 year 4 months 24 days
Stock compensation expense	$ 787,000	$ 342,000
Research And Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	(9,000)	55,000
Research And Development Expense [Member] | Warrant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	$ (84,000)	$ 59,000