Segment Information - Reconciliation of Operating Profit (Loss) from Segments to Consolidated (Parenthetical) (Detail) - USD ($) $ in Millions  | 
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2021  | 
Jun. 30, 2020  | 
Jun. 30, 2021  | 
Jun. 30, 2020  | 
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| Selling, General and Administrative Expenses [Member] | China [Member] | ||||
| Segment Reporting Reconciling Item For Operating Profit Loss From Segment To Consolidated [Line Items] | ||||
| Independent service providers service fees costs | $ 98.2 | $ 122.2 | $ 193.2 | $ 227.9 | 
| X | ||||||||||
- Definition Independent service providers service fee costs. No definition available. 
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| X | ||||||||||
- Definition 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. No definition available. 
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| X | ||||||||||
- Details 
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| X | ||||||||||
- Details 
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