Fair Value of Financial Instruments - Financial Assets and Liabilities Carried at Fair Value (Detail) - USD ($) $ in Millions | Jul. 31, 2017 | Jan. 31, 2017 | Jul. 31, 2016 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Total financial assets, Fair Value | | $ 264.5 | $ 108.1 | $ 116.3 |
Total financial liabilities, Fair Value | | 20.7 | 8.9 | 21.4 |
Other assets, net [Member] | Marketable securities [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial Assets, Fair Value | [1] | 33.7 | 36.4 | 35.5 |
Short-term Investments [Member] | Bank Time Deposits [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial Assets, Fair Value | [2] | 222.7 | 57.8 | 53.8 |
Prepaid Expenses and Other Current Assets [Member] | Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 2.3 | 3.6 | 22.2 |
Prepaid Expenses and Other Current Assets [Member] | Precious Metal Collars [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0.2 | 0.4 | 1.4 |
Prepaid Expenses and Other Current Assets [Member] | Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 4.7 | 9.6 | 2.1 |
Prepaid Expenses and Other Current Assets [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0.9 | 0.3 | 1.3 |
Accounts Payable and Accrued Liabilities [Member] | Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 6.7 | 5.4 | |
Accounts Payable and Accrued Liabilities [Member] | Precious Metal Collars [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0.4 | 0.3 | 0.7 |
Accounts Payable and Accrued Liabilities [Member] | Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 2.3 | 0.6 | 14.3 |
Accounts Payable and Accrued Liabilities [Member] | Currency Swap [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 9.1 | 0.4 | 3.6 |
Accounts Payable and Accrued Liabilities [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 2.2 | 2.2 | 2.8 |
Level 1 [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Total financial assets, Fair Value | | 256.4 | 94.2 | 89.3 |
Total financial liabilities, Fair Value | | 0 | 0 | 0 |
Level 1 [Member] | Other assets, net [Member] | Marketable securities [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial Assets, Fair Value | [1] | 33.7 | 36.4 | 35.5 |
Level 1 [Member] | Short-term Investments [Member] | Bank Time Deposits [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial Assets, Fair Value | [2] | 222.7 | 57.8 | 53.8 |
Level 1 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0 | 0 | 0 |
Level 1 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Collars [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0 | 0 | 0 |
Level 1 [Member] | Prepaid Expenses and Other Current Assets [Member] | Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0 | 0 | 0 |
Level 1 [Member] | Prepaid Expenses and Other Current Assets [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0 | 0 | 0 |
Level 1 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0 | 0 | |
Level 1 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Collars [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0 | 0 | 0 |
Level 1 [Member] | Accounts Payable and Accrued Liabilities [Member] | Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0 | 0 | 0 |
Level 1 [Member] | Accounts Payable and Accrued Liabilities [Member] | Currency Swap [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0 | 0 | 0 |
Level 1 [Member] | Accounts Payable and Accrued Liabilities [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0 | 0 | 0 |
Level 2 [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Total financial assets, Fair Value | | 8.1 | 13.9 | 27 |
Total financial liabilities, Fair Value | | 20.7 | 8.9 | 21.4 |
Level 2 [Member] | Other assets, net [Member] | Marketable securities [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial Assets, Fair Value | [1] | 0 | 0 | 0 |
Level 2 [Member] | Short-term Investments [Member] | Bank Time Deposits [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial Assets, Fair Value | [2] | 0 | 0 | 0 |
Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 2.3 | 3.6 | 22.2 |
Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Collars [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0.2 | 0.4 | 1.4 |
Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member] | Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 4.7 | 9.6 | 2.1 |
Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0.9 | 0.3 | 1.3 |
Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 6.7 | 5.4 | |
Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Collars [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0.4 | 0.3 | 0.7 |
Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member] | Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 2.3 | 0.6 | 14.3 |
Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member] | Currency Swap [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 9.1 | 0.4 | 3.6 |
Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 2.2 | 2.2 | 2.8 |
Level 3 [Member] | | | | |
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 [Member] | Other assets, net [Member] | Marketable securities [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial Assets, Fair Value | [1] | 0 | 0 | 0 |
Level 3 [Member] | Short-term Investments [Member] | Bank Time Deposits [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Financial Assets, Fair Value | [2] | 0 | 0 | 0 |
Level 3 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0 | 0 | 0 |
Level 3 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Collars [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0 | 0 | 0 |
Level 3 [Member] | Prepaid Expenses and Other Current Assets [Member] | Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0 | 0 | 0 |
Level 3 [Member] | Prepaid Expenses and Other Current Assets [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Assets, Fair Value | [3] | 0 | 0 | 0 |
Level 3 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Forward Contracts [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0 | 0 | |
Level 3 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Collars [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0 | 0 | 0 |
Level 3 [Member] | Accounts Payable and Accrued Liabilities [Member] | Foreign Exchange Contract [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0 | 0 | 0 |
Level 3 [Member] | Accounts Payable and Accrued Liabilities [Member] | Currency Swap [Member] | Cash Flow Hedging [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | 0 | 0 | 0 |
Level 3 [Member] | Accounts Payable and Accrued Liabilities [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Derivative Liability, Fair Value | [4] | $ 0 | $ 0 | $ 0 |
| |
[1] | Included within Other assets, net. | |
[2] | Included within Short-term investments. | |
[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. | |