Collaboration, License and Success Payment Agreements - 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
Fred Hutch | Ten Times
Collaborative Arrangement and Arrangement Other than Collaborative [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
Fred Hutch | Twenty Times
Collaborative Arrangement and Arrangement Other than Collaborative [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
Fred Hutch | Thirty Times
Collaborative Arrangement and Arrangement Other than Collaborative [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
Fred Hutch | Forty Times
Collaborative Arrangement and Arrangement Other than Collaborative [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
Fred Hutch | Fifty Times
Collaborative Arrangement and Arrangement Other than Collaborative [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
Stanford | Ten Times
Collaborative Arrangement and Arrangement Other than Collaborative [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
Stanford | Twenty Times
Collaborative Arrangement and Arrangement Other than Collaborative [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
Stanford | Thirty Times
Collaborative Arrangement and Arrangement Other than Collaborative [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
Stanford | Forty Times
Collaborative Arrangement and Arrangement Other than Collaborative [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
Stanford | Fifty Times
Collaborative Arrangement and Arrangement Other than Collaborative [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