Related-Party Transactions - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Related Party Transaction [Line Items]
Total expenses	$ 0		$ 0
Patent No. 8,420,051 [Member]
Related Party Transaction [Line Items]
Expected patent expiration year			2029
Consulting Agreement [Member]
Related Party Transaction [Line Items]
Consulting agreement fees paid to Prof. Dr. Skerra	0	$ 6,000	$ 0	$ 17,000
TUM [Member]
Related Party Transaction [Line Items]
Patent expiration year			2027
Total expenses	$ 0	$ 14,000	$ 0	$ 42,000