Basis of Presentation and Business Overview - Additional Information (Detail) $ / shares in Units, $ in Thousands		3 Months Ended
Mar. 15, 2021 USD ($) $ / shares	Mar. 31, 2022 USD ($) Segment $ / shares
Basis Of Presentation [Line Items]
Number of reportable segments \| Segment		2
Viela Bio [Member]
Basis Of Presentation [Line Items]
Business Acquisition, Date of Acquisition Agreement	Mar. 15, 2021
Share price \| $ / shares		$ 53.00
Total consideration for acquisition \| $	$ 3,000,000	$ 2,994,091
Cash acquired from acquisition \| $	$ 342,300	$ 342,300
Ordinary Shares [Member] \| Viela Bio [Member]
Basis Of Presentation [Line Items]
Share price \| $ / shares	$ 53.00

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Date when the acquirer obtains control of the acquiree, in YYYY-MM-DD format.

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Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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The cash inflow associated with the acquisition of business during the period (for example, cash that was held by the acquired business).

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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