Fair Value of Financial Instruments - Financial Assets and Liabilities Carried at Fair Value (Details) - USD ($) $ in Millions | Apr. 30, 2019 | Jan. 31, 2019 | Apr. 30, 2018 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Total financial assets, fair value | | $ 99.4 | $ 106.9 | $ 253.9 |
Total financial liabilities, fair value | | 9.5 | 27.4 | 31.8 |
Short-term Investments | Bank Time Deposits | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial assets, fair value | [1] | 53.2 | 62.7 | 212.7 |
Other assets, net | Marketable securities | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial assets, fair value | [2] | 37.4 | 36.3 | 37.1 |
Prepaid expenses and other current assets | Cash Flow Hedging | Precious Metal Forward Contracts | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 3.3 | 5.2 | 1.8 |
Prepaid expenses and other current assets | Cash Flow Hedging | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 3.4 | 1.8 | 0.9 |
Prepaid expenses and other current assets | Not Designated as Hedging Instrument | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 2.1 | 0.9 | 1.4 |
Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Precious Metal Forward Contracts | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0.8 | 2.7 | 5 |
Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0.1 | 2.1 | 2.4 |
Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Currency Swap | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 8.1 | 19.9 | 23.6 |
Accounts Payable and Accrued Liabilities | Not Designated as Hedging Instrument | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0.5 | 2.7 | 0.8 |
Level 1 | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Total financial assets, fair value | | 90.6 | 99 | 249.8 |
Total financial liabilities, fair value | | 0 | 0 | 0 |
Level 1 | Short-term Investments | Bank Time Deposits | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial assets, fair value | [1] | 53.2 | 62.7 | 212.7 |
Level 1 | Other assets, net | Marketable securities | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial assets, fair value | [2] | 37.4 | 36.3 | 37.1 |
Level 1 | Prepaid expenses and other current assets | Cash Flow Hedging | Precious Metal Forward Contracts | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 0 | 0 | 0 |
Level 1 | Prepaid expenses and other current assets | Cash Flow Hedging | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 0 | 0 | 0 |
Level 1 | Prepaid expenses and other current assets | Not Designated as Hedging Instrument | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 0 | 0 | 0 |
Level 1 | Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Precious Metal Forward Contracts | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0 | 0 | 0 |
Level 1 | Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0 | 0 | 0 |
Level 1 | Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Currency Swap | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0 | 0 | 0 |
Level 1 | Accounts Payable and Accrued Liabilities | Not Designated as Hedging Instrument | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0 | 0 | 0 |
Level 2 | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Total financial assets, fair value | | 8.8 | 7.9 | 4.1 |
Total financial liabilities, fair value | | 9.5 | 27.4 | 31.8 |
Level 2 | Short-term Investments | Bank Time Deposits | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial assets, fair value | [1] | 0 | 0 | 0 |
Level 2 | Other assets, net | Marketable securities | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial assets, fair value | [2] | 0 | 0 | 0 |
Level 2 | Prepaid expenses and other current assets | Cash Flow Hedging | Precious Metal Forward Contracts | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 3.3 | 5.2 | 1.8 |
Level 2 | Prepaid expenses and other current assets | Cash Flow Hedging | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 3.4 | 1.8 | 0.9 |
Level 2 | Prepaid expenses and other current assets | Not Designated as Hedging Instrument | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 2.1 | 0.9 | 1.4 |
Level 2 | Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Precious Metal Forward Contracts | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0.8 | 2.7 | 5 |
Level 2 | Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0.1 | 2.1 | 2.4 |
Level 2 | Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Currency Swap | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 8.1 | 19.9 | 23.6 |
Level 2 | Accounts Payable and Accrued Liabilities | Not Designated as Hedging Instrument | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0.5 | 2.7 | 0.8 |
Level 3 | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Total financial assets, fair value | | 0 | 0 | 0 |
Total financial liabilities, fair value | | 0 | 0 | 0 |
Level 3 | Short-term Investments | Bank Time Deposits | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial assets, fair value | [1] | 0 | 0 | 0 |
Level 3 | Other assets, net | Marketable securities | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial assets, fair value | [2] | 0 | 0 | 0 |
Level 3 | Prepaid expenses and other current assets | Cash Flow Hedging | Precious Metal Forward Contracts | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 0 | 0 | 0 |
Level 3 | Prepaid expenses and other current assets | Cash Flow Hedging | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 0 | 0 | 0 |
Level 3 | Prepaid expenses and other current assets | Not Designated as Hedging Instrument | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative assets, fair value | [3] | 0 | 0 | 0 |
Level 3 | Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Precious Metal Forward Contracts | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0 | 0 | 0 |
Level 3 | Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0 | 0 | 0 |
Level 3 | Accounts Payable and Accrued Liabilities | Cash Flow Hedging | Currency Swap | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | 0 | 0 | 0 |
Level 3 | Accounts Payable and Accrued Liabilities | Not Designated as Hedging Instrument | Foreign Exchange Forward | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative liability, fair value | [4] | $ 0 | $ 0 | $ 0 |
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[1] | Included within Short-term investments. | |
[2] | Included within Other assets, net. | |
[3] | Included within Prepaid expenses and other current assets or Other assets, net based on the maturity of the contract. | |
[4] | Included within Accounts payable and accrued liabilities or Other long-term liabilities based on the maturity of the contract. | |