Grant Revenue - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
Feb. 28, 2018	Dec. 31, 2018	Dec. 31, 2017
Disaggregation Of Revenue [Line Items]
Revenue		$ 668,000
Type of Revenue [Extensible List]		us-gaap:GrantMember	us-gaap:GrantMember
SBIR Grants
Disaggregation Of Revenue [Line Items]
Revenue		$ 700,000	$ 0
Grants from the National Institutes of Health	$ 2,800,000
Type of Revenue [Extensible List]		us-gaap:GrantMember	us-gaap:GrantMember

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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