License, Collaboration, and Success Payment Agreements - Schedule of Aggregate Potential Success Payments (Details) - Collaborative Arrangement, Transaction with Party to Collaborative Arrangement $ / shares in Units, $ in Millions	Oct. 31, 2020 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares
Ten Times | Fred Hutch
Description Of Organization [Line Items]
Multiple of initial equity value at issuance		10
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 18.29
Aggregate success payment(s) (in millions) | $		$ 10
Ten Times | Stanford
Description Of Organization [Line Items]
Multiple of initial equity value at issuance	10
Per share common stock price required for payment (in dollars per share) | $ / shares	$ 18.29
Aggregate success payment(s) (in millions) | $	$ 10
Twenty Times | Fred Hutch
Description Of Organization [Line Items]
Multiple of initial equity value at issuance		20
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 36.58
Aggregate success payment(s) (in millions) | $		$ 40
Twenty Times | Stanford
Description Of Organization [Line Items]
Multiple of initial equity value at issuance	20
Per share common stock price required for payment (in dollars per share) | $ / shares	$ 36.58
Aggregate success payment(s) (in millions) | $	$ 40
Thirty Times | Fred Hutch
Description Of Organization [Line Items]
Multiple of initial equity value at issuance		30
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 54.86
Aggregate success payment(s) (in millions) | $		$ 90
Thirty Times | Stanford
Description Of Organization [Line Items]
Multiple of initial equity value at issuance	30
Per share common stock price required for payment (in dollars per share) | $ / shares	$ 54.86
Aggregate success payment(s) (in millions) | $	$ 90
Forty Times | Fred Hutch
Description Of Organization [Line Items]
Multiple of initial equity value at issuance		40
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 73.15
Aggregate success payment(s) (in millions) | $		$ 140
Forty Times | Stanford
Description Of Organization [Line Items]
Multiple of initial equity value at issuance	40
Per share common stock price required for payment (in dollars per share) | $ / shares	$ 73.15
Aggregate success payment(s) (in millions) | $	$ 140
Fifty Times | Fred Hutch
Description Of Organization [Line Items]
Multiple of initial equity value at issuance		50
Per share common stock price required for payment (in dollars per share) | $ / shares		$ 91.44
Aggregate success payment(s) (in millions) | $		$ 200
Fifty Times | Stanford
Description Of Organization [Line Items]
Multiple of initial equity value at issuance	50
Per share common stock price required for payment (in dollars per share) | $ / shares	$ 91.44
Aggregate success payment(s) (in millions) | $	$ 200