Summary of Significant Accounting Policies - Additional Information (Details)			12 Months Ended
	Mar. 27, 2020	Jun. 01, 2014 USD ($)	Dec. 31, 2020 USD ($) Subsidary	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Impairments of long-lived assets			$ 0	$ 0	$ 0
Net operating loss carryback period	5 years
Net operating loss carryforwards taxable income suspension of annual deduction limitation percentage	80.00%
United States
Summary Of Significant Accounting Policies [Line Items]
Number of subsidiary corporations owned | Subsidary			9
Maximum
Summary Of Significant Accounting Policies [Line Items]
Marketable securities stated maturity period			1 year
Maximum | CPRIT
Summary Of Significant Accounting Policies [Line Items]
Research grant contract amount		$ 19,800,000