Grant Revenues - Additional Information (Details) - USD ($)		3 Months Ended
	Jun. 30, 2015	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Research And Development Arrangement Contract To Perform For Others [Line Items]
Grant revenues		$ 859,000	$ 0
CPRIT
Research And Development Arrangement Contract To Perform For Others [Line Items]
Grant contract term	3 years
Grant contract beginning date	Jun. 01, 2014
Grant contract expiration date	May 31, 2017
Outstanding grant receivable		1,600,000		$ 1,700,000
CPRIT | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research grant contract amount	$ 19,800,000	$ 19,800,000