Balance Sheet Components - Additional Information (Detail)	3 Months Ended
Mar. 31, 2020 USD ($) Milestone	Dec. 31, 2019 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 121,560,000	$ 126,266,000
Contractual maturities of available-for-sale investments	1 year
Other-than-temporary impairment loss	$ 0
Number of regulatory milestones \| Milestone	2
Unbilled contract assets	$ 130,000,000	180,000,000
Active pharmaceutical ingredient product price change in estimated variable consideration	0	36,324,000
Accrued long-term co-promotional expenses	78,301,000	53,071,000
Accounts Receivable [Member]
Schedule of Available-for-sale Securities [Line Items]
Billed contract assets	50,000,000.0
Europe [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	130,000,000.0
Astellas Agreement [Member] \| Europe [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	130,000,000.0
AstraZeneca Agreements [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets	50,000,000.0
Accrued long-term co-promotional expenses	78,300,000	53,100,000
AstraZeneca Agreements [Member] \| U.S./RoW [Member]
Schedule of Available-for-sale Securities [Line Items]
Unbilled contract assets		50,000,000.0
Foreign subsidiaries [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 29,800,000	$ 11,900,000

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