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Balance Sheet Components - Additional Information (Detail) - USD ($) | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2021 | Jul. 31, 2021 | Dec. 31, 2020
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Cash and cash equivalents | $ 274,527,000 | $ 274,527,000 |  | $ 678,393,000
Other-than-temporary impairment loss | 0 | 0 |  |
Net unbilled co-development revenue | 8,000,000 | 8,000,000 |  | 0
Profit share liability | 23,256,000 | 23,256,000 |  | $ 6,547,000
Eluminex [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Unbilled upfront payment | 8,000,000.0 | 8,000,000.0 | $ 8,000,000.0 |
AstraZeneca Agreements [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Net unbilled co-development revenue | $ 7,000,000.0 | $ 7,000,000.0 |  |
U.S. [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Percentage of pre-launch inventory capitalized of aggregate inventory balance | 40.00% | 40.00% |  | 29.00%
China [Member] | AstraZeneca Agreements [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Unbilled upfront payment | $ 77,200,000 | $ 77,200,000 |  |
Profit share liability | 7,800,000 | $ 7,800,000 |  | $ 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 | $ 77,400,000 | $ 77,400,000 |  | $ 66,000,000.0

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