Balance Sheet Components - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 353,361,000	$ 353,361,000	$ 678,393,000
Other-than-temporary impairment loss	$ 0	$ 0
Percentage of pre-launch inventory capitalized of aggregate inventory balance	37.00%	37.00%	29.00%
Net unbilled co-development revenue	$ 0	$ 0	$ 0
Profit share liability	25,234,000	25,234,000	6,547,000
AstraZeneca Agreements [Member]
Schedule of Available-for-sale Securities [Line Items]
Net unbilled co-development revenue	5,300,000	5,300,000
AstraZeneca Agreements [Member] \| China [Member]
Schedule of Available-for-sale Securities [Line Items]
Profit share liability	7,000,000.0	$ 7,000,000.0	7,000,000.0
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Contractual maturities of available-for-sale investments		2 years
Foreign subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 85,100,000	$ 85,100,000	$ 66,000,000.0

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Percentage of pre-launch inventory capitalized of aggregate inventory balance.

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Supplies, net.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

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The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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