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Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Millions | Jun. 30, 2020 | Dec. 31, 2019
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Available-for-sale investments | $ 178.1 | $ 109.4
Short-term investments | 178.1 | 109.4
Commercial Paper [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Available-for-sale investments | 3.8 | 61.2
Fair Value Measurements, Recurring [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents | 81.7 | 65.2
Total assets | 285.6 | 201.5
Total liabilities | 16.5 | 6.8
Short-term investments | 178.1 | 109.4
Other current assets | 1.6 | 1.9
Total current assets | 261.4 | 176.5
Long-term investments | 6.0 | 5.8
Other assets | 18.2 | 19.2
Total long-term assets | 24.2 | 25.0
Fair Value Measurements, Recurring [Member] | Foreign Exchange Contracts [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivatives – currency forward contracts | 1.6 | 1.1
Derivatives – currency forward contracts | 0.9 | 0.3
Fair Value Measurements, Recurring [Member] | Interest Rate Hedge [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivatives – interest rate hedge – current | 0.3 |
Derivatives – interest rate hedge – non-current | 15.3 | 6.5
Derivatives –interest rate hedge - current |  | 0.8
Fair Value Measurements, Recurring [Member] | Commercial Paper [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents |  | 42.6
Available-for-sale investments | 3.8 | 61.2
Fair Value Measurements, Recurring [Member] | Group Insurance Contracts [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Available-for-sale investments | 6.0 | 5.8
Fair Value Measurements, Recurring [Member] | Israeli Pension Assets [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Pension assets | 16.7 | 16.7
Fair Value Measurements, Recurring [Member] | Money Market Funds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents | 9.3 | 0.6
Deferred compensation plan assets | 0.1 | 0.5
Fair Value Measurements, Recurring [Member] | Time Deposits and Certificates of Deposit [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents |  | 2.2
Available-for-sale investments | 0.3 | 13.1
Fair Value Measurements, Recurring [Member] | U.S. Treasury Obligations [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents | 47.6 | 2.7
Available-for-sale investments | 165.2 | 5.0
Fair Value Measurements, Recurring [Member] | U.S. Agency Obligations [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents | 24.8 | 17.1
Available-for-sale investments | 6.3 | 26.1
Fair Value Measurements, Recurring [Member] | Bankers' Acceptance Drafts [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Available-for-sale investments | 2.5 | 4.0
Fair Value Measurements, Recurring [Member] | Mutual Funds and Exchange Traded Funds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Deferred compensation plan assets | 1.4 | 2.0
Fair Value Measurements, Recurring [Member] | Other Current Liabilities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Total liabilities | 1.2 | 0.3
Fair Value Measurements, Recurring [Member] | Other Noncurrent Liabilities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Total liabilities | 15.3 | 6.5
Fair Value Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents | 9.3 | 0.6
Total assets | 9.3 | 0.6
Total current assets | 9.3 | 0.6
Fair Value Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Money Market Funds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents | 9.3 | 0.6
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents | 72.4 | 64.6
Total assets | 276.3 | 200.9
Total liabilities | 16.5 | 6.8
Short-term investments | 178.1 | 109.4
Other current assets | 1.6 | 1.9
Total current assets | 252.1 | 175.9
Long-term investments | 6.0 | 5.8
Other assets | 18.2 | 19.2
Total long-term assets | 24.2 | 25.0
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign Exchange Contracts [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivatives – currency forward contracts | 1.6 | 1.1
Derivatives – currency forward contracts | 0.9 | 0.3
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Hedge [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivatives – interest rate hedge – current | 0.3 |
Derivatives – interest rate hedge – non-current | 15.3 | 6.5
Derivatives –interest rate hedge - current |  | 0.8
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Commercial Paper [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents |  | 42.6
Available-for-sale investments | 3.8 | 61.2
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Group Insurance Contracts [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Available-for-sale investments | 6.0 | 5.8
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Israeli Pension Assets [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Pension assets | 16.7 | 16.7
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Money Market Funds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Deferred compensation plan assets | 0.1 | 0.5
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Time Deposits and Certificates of Deposit [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents |  | 2.2
Available-for-sale investments | 0.3 | 13.1
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury Obligations [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents | 47.6 | 2.7
Available-for-sale investments | 165.2 | 5.0
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Agency Obligations [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash and cash equivalents | 24.8 | 17.1
Available-for-sale investments | 6.3 | 26.1
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Bankers' Acceptance Drafts [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Available-for-sale investments | 2.5 | 4.0
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mutual Funds and Exchange Traded Funds [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Deferred compensation plan assets | 1.4 | 2.0
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Current Liabilities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Total liabilities | 1.2 | 0.3
Fair Value Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Noncurrent Liabilities [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Total liabilities | $ 15.3 | $ 6.5

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- Definition Investments in debt and equity securities which are categorized neither as held-to-maturity nor trading and which are intended to be sold or mature more than one year from the balance sheet date or operating cycle, if longer. Such securities are reported at fair value; unrealized gains (losses) related to Available-for-sale Securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain (loss) of an Available-for-sale security that is designated as being hedged in a fair value hedge is recognized in earnings during the period of the hedge, as are other than temporary declines in fair value below the cost basis for investments in equity securities and debt securities that an entity intends to sell or it is more likely than not that it will be required to sell before the recovery of its amortized cost basis. Other than temporary declines in fair value below the cost basis for debt securities categorized as Available-for-sale that an entity does not intend to sell and for which it is not more likely than not that the entity will be required to sell before the recovery of its amortized cost basis are bifurcated into credit losses and losses related to all other factors. Other than temporary declines in fair value below cost basis related to credit losses are recognized in earnings, and losses related to all other factors are recognized in other comprehensive income. + References No definition available. + Details
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