Commitments - Summary of Lease Arrangements of Company Facilities (Detail)	3 Months Ended
	Mar. 31, 2021 ft²
Vacaville, CA [Member] | Manufacturing [Member]
Property Subject To Or Available For Operating Lease [Line Items]
Approximate Square Feet	24,634
Expiration	Lease expires 2023
Lease expiration year	2023
Cupertino, CA [Member] | Office, Laboratory and Manufacturing [Member]
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration year	2024
Lease renewal term	5 years
Cupertino, CA [Member] | Office, Laboratory and Manufacturing [Member] | Lease Amendment [Member]
Property Subject To Or Available For Operating Lease [Line Items]
Approximate Square Feet	30,149
Expiration	Lease expires 2024 (with an option to renew for an additional five years)
Cupertino, CA [Member] | Office and Laboratory [Member]
Property Subject To Or Available For Operating Lease [Line Items]
Lease expiration year	2024
Lease renewal term	5 years
Cupertino, CA [Member] | Office and Laboratory [Member] | Lease Amendment [Member]
Property Subject To Or Available For Operating Lease [Line Items]
Approximate Square Feet	20,100
Expiration	Lease expires 2024 (with an option to renew for an additional five years)