Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021 USD ($) ft² Segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2020 USD ($)
Significant Accounting Policies [Line Items]
Number of operating segments | Segment	1
Number of reportable segments | Segment	1
Impairment charges	$ 0	$ 0	$ 0
Operating lease expiration year	2031
Trailer bill		0
Right-of-use assets	$ 104,968,000	12,781,000
Operating lease, liabilities	113,555,000
Operating lease, current liabilities	5,100,000
Operating lease liabilities, noncurrent	116,887,000	15,243,000
Accumulated deficit	$ (275,354,000)	$ (328,184,000)
ASU 2016-02
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 01, 2020
Right-of-use assets				$ 5,800,000
Operating lease, liabilities				10,100,000
Operating lease, current liabilities				1,200,000
Operating lease liabilities, noncurrent				8,900,000
Deferred rent balance				4,300,000
ASU 2016-02 | Cumulative Effect, Period of Adoption, Adjustment
Significant Accounting Policies [Line Items]
Accumulated deficit				$ 0
Brisbane, California
Significant Accounting Policies [Line Items]
Operating lease expiration year	2031
Brisbane, California | Office Space
Significant Accounting Policies [Line Items]
Square feet of leased office | ft²	109,237
Hayward, California | Executive Offices Research and Development and Business Operations
Significant Accounting Policies [Line Items]
Square feet of leased office | ft²	136,293
Minimum
Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives	1 year
Maximum
Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives	5 years