Leases - Schedule of Description of Operating Lease (Detail) - Office/Laboratory [Member]	3 Months Ended
	Mar. 31, 2020 ft²
12780 El Camino Real
Leases [Line Items]
Square Feet	141,000	[1]
Commencement Date	Aug. 07, 2019	[1]
Expiration Date	Jul. 31, 2031	[1]
12790 El Camino Real, Suite 130
Leases [Line Items]
Square Feet	2,000	[1]
Commencement Date	Dec. 01, 2019	[1]
Expiration Date	Jul. 31, 2031	[1]
12790 El Camino Real, Suite 150
Leases [Line Items]
Square Feet	8,000	[1]
Commencement Date	Aug. 07, 2019	[1]
Expiration Date	Jul. 31, 2031	[1]
12790 El Camino Real, Suite 300
Leases [Line Items]
Square Feet	28,000	[1]
Commencement Date	Dec. 01, 2019	[1]
Expiration Date	Jul. 31, 2031	[1]
12777 High Bluff Drive
Leases [Line Items]
Square Feet	45,000	[2]
Commencement Date	Jul. 01, 2018	[2]
Expiration Date	Jul. 31, 2029	[2]
12790 El Camino Real, Suite 200
Leases [Line Items]
Square Feet	28,000	[1]
Commencement Date	Feb. 01, 2021	[1]
Expiration Date	Jul. 31, 2031	[1]
12790 El Camino Real, Suite 100
Leases [Line Items]
Square Feet	17,000	[1]
Commencement Date	Feb. 01, 2021	[1]
Expiration Date	Jul. 31, 2031	[1]

[1] Under the terms of the lease, we have two options to extend the term of the lease for a period of ten years each. We were not reasonably certain to exercise either of these options at lease commencement. As such, neither option was recognized as part of the associated operating lease right-of-use asset or liability. In connection with the lease, in lieu of a cash security deposit, Wells Fargo Bank, N.A., or Well Fargo, issued a $3.0 million letter of credit on our behalf, which is secured by a deposit of equal amount.

[2] Under the terms of the lease, we do not have the option to extend the lease. In lieu of a cash security deposit, Wells Fargo issued a $1.0 million letter of credit on our behalf, which is secured by a deposit of $0.2 million