Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares  | 
Jun. 30, 2021  | 
Dec. 31, 2020  | 
|---|---|---|
| Statement Of Financial Position [Abstract] | ||
| Common shares, par value | $ 0.0005 | $ 0.0005 | 
| Common shares, shares authorized | 2,000,000,000.0 | 2,000,000,000.0 | 
| Common shares, shares outstanding | 106,300,000 | 120,100,000 | 
| Treasury stock shares, at cost | 10,000,000.0 | 10,000,000.0 | 
| X | ||||||||||
- Definition Face amount or stated value per share of common stock. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
- Definition The maximum number of common shares permitted to be issued by an entity's charter and bylaws. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
- Definition Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
- References No definition available. 
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| X | ||||||||||
- Definition Number of previously issued common shares repurchased by the issuing entity and held in treasury. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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