Employee Benefit Plan - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Molecular Templates 401(k) Plan
Defined Contribution Plan Disclosure [Line Items]
Employer discretionary contribution amount	$ 0.5	$ 0.2

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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