Grant Revenues - Additional Information (Details) - USD ($)		3 Months Ended							12 Months Ended
	Jun. 30, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Research And Development Arrangement Contract To Perform For Others [Line Items]
Grant revenues		$ 1,247,000	$ 1,149,000	$ 1,373,000	$ 859,000	$ 1,585,000	$ 1,073,000	$ 3,427,000	$ 4,628,000	$ 6,085,000	$ 0
Outstanding grant receivable		1,215,000				1,697,000			1,215,000	1,697,000
Deferred revenue		$ 71,000				$ 0			71,000	$ 0
CPRIT
Research And Development Arrangement Contract To Perform For Others [Line Items]
Grant contract term	4 years
Grant contract beginning date	Jun. 01, 2014
Grant contract expiration date	May 31, 2018
CPRIT | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research grant contract amount	$ 19,800,000								$ 19,800,000