Commitments and Contingencies (Details) - USD ($)	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019
Commitments and Contingencies
Licensed product sales	$ 0	$ 0
Research, Development and Commercialization Agreement \| Hoffmann-La Roche ("Roche")
Commitments and Contingencies
Remainder of future milestone payments	$ 8,000,000

Amount, including 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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+ Details