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Investments - Investments Classified as Short-Term Available-for-Sale Investments (Detail) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
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Schedule of Available-for-sale Securities [Line Items] |  |
Investments classified as short-term | $ 227.7 | $ 109.4
Time Deposits and Certificates of Deposit [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Investments classified as short-term | 0.7 | 13.1
Bankers' Acceptance Drafts [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Investments classified as short-term | 3.8 | 4.0
Commercial Paper [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Investments classified as short-term |  | 61.2
U.S. Treasury Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Investments classified as short-term | $ 223.2 | 5.0
U.S. Agency Obligations [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Investments classified as short-term |  | $ 26.1

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References No definition available. + Details
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- 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. + References No definition available. + Details
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