Commitment and Contingencies - Additional Information (Details)					1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 19, 2020 USD ($) ft²	Sep. 30, 2019 USD ($) ft²	Oct. 28, 2018 USD ($) ft²	Sep. 30, 2015 USD ($) ft²	Apr. 30, 2019 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) Lawsuit	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2020 USD ($)
Long Term Purchase Commitment [Line Items]
Lease payments					$ 3,500,000		$ 3,168,000	$ 700,000	$ 500,000
Amended lease term from the date of relocation					7 years
Operating lease right-of-use asset						$ 23,066,000	23,066,000			$ 1,400,000
Operating lease liability						21,639,000	21,639,000			1,800,000
Finance lease liability						0	0
Operating lease right-of-use asset						23,066,000	$ 23,066,000			1,400,000
Lawsuits Filed Against Company | Lawsuit							7
Litigation settlement expense						200,000
Topic 842
Long Term Purchase Commitment [Line Items]
Lease payments							$ 900,000
Operating lease right-of-use asset										1,400,000
Operating lease liability										1,800,000
Finance lease liability						0	0
Operating lease right-of-use asset										$ 1,400,000
Menlo Park Lease Agreement [Member]
Long Term Purchase Commitment [Line Items]
Office lease space | ft²	4,862	7,973		17,352
Lease payments	$ 300,000	$ 400,000		$ 3,400,000
Tenant improvements				$ 800,000
Lease expiration date	Mar. 31, 2022	Mar. 31, 2022		Mar. 31, 2022
Operating leases commencement date	Oct. 01, 2020	Oct. 01, 2019
Letters of Credit issued amount						200,000	200,000
Redwood City Lease Agreement [Member]
Long Term Purchase Commitment [Line Items]
Office lease space | ft²			50,305
Lease payments			$ 29,500,000
Tenant improvements			$ 3,000,000.0
Lease expiration date			Feb. 28, 2030
Letters of Credit issued amount									$ 4,100,000
Boston, Massachusetts [Member]
Long Term Purchase Commitment [Line Items]
Letters of Credit issued amount						$ 200,000	$ 200,000