Stockholders' Equity - Summary of Non-cash Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation expense	$ 847	$ 633	$ 2,984	$ 1,660
Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation expense	449	315	1,351	880
General and Administrative Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Non-cash stock-based compensation expense	$ 398	$ 318	$ 1,633	$ 780

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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