Leases - Disclosure (Detail) $ in Millions	Sep. 30, 2020 USD ($) ft² renewalOption	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Restricted cash | $	$ 3.2	$ 3.2
Letter of Credit
Lessee, Lease, Description [Line Items]
Restricted cash | $	$ 3.2
12780/12790 El Camino Real Master Lease [Member]
Lessee, Lease, Description [Line Items]
Number of renewal options | renewalOption	2
Renewal term	10 years
12780 El Camino Real
Lessee, Lease, Description [Line Items]
Square feet	141,000
12790 El Camino Real, Suite 130
Lessee, Lease, Description [Line Items]
Square feet	2,000
12790 El Camino Real, Suite 150
Lessee, Lease, Description [Line Items]
Square feet	8,000
12790 El Camino Real, Suite 300
Lessee, Lease, Description [Line Items]
Square feet	28,000
12777 High Bluff Drive
Lessee, Lease, Description [Line Items]
Square feet	45,000
12790 El Camino Real, Suite 200
Lessee, Lease, Description [Line Items]
Square feet	28,000
12790 El Camino Real, Suite 100
Lessee, Lease, Description [Line Items]
Square feet	17,000