Grant Revenues - Additional Information (Details) - USD ($)		3 Months Ended		48 Months Ended
	Jun. 01, 2014	Mar. 31, 2019	Mar. 31, 2018	May 31, 2018
Research And Development Arrangement Contract To Perform For Others [Line Items]
Grant revenues		$ 0	$ 1,510,000
Type of revenue [extensible list]		us-gaap:GrantMember	us-gaap:GrantMember
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
Grant revenues				$ 19,800,000
Type of revenue [extensible list]				us-gaap:GrantMember
CPRIT | Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research grant contract amount	$ 19,800,000