Fair Value of Financial Instruments - Financial Assets and Liabilities Carried at Fair Value (Detail) - USD ($) $ in Millions		Oct. 31, 2017		Jan. 31, 2017		Oct. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets, Fair Value		$ 204.6		$ 108.1		$ 105.4
Total financial liabilities, Fair Value		12.9		8.9		20.4
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]	32.1		36.4		35.4
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]	164.4		57.8		59.2
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]	1.9		0.3		0.6
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]	0.6		2.2		3.1
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets, Fair Value		196.5		94.2		94.6
Total financial liabilities, Fair Value		0.0		0.0		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]	32.1		36.4		35.4
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]	164.4		57.8		59.2
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		0.0		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		0.0		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		10.8
Total financial liabilities, Fair Value		12.9		8.9		20.4
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		0.0		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		0.0		0.0
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]	1.9		0.3		0.6
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]	0.6		2.2		3.1
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets, Fair Value		0.0		0.0		0.0
Total financial liabilities, Fair Value		0.0		0.0		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		0.0		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		0.0		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		0.0		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		0.0		0.0
Cash Flow Hedging [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	1.9		3.6		6.0
Cash Flow Hedging [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Collars [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]			0.4		1.0
Cash Flow Hedging [Member] | Prepaid Expenses and Other Current Assets [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	3.4		9.6		3.2
Cash Flow Hedging [Member] | Prepaid Expenses and Other Current Assets [Member] | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	0.9
Cash Flow Hedging [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	6.2		5.4		4.3
Cash Flow Hedging [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Collars [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	0.3		0.3		0.5
Cash Flow Hedging [Member] | Accounts Payable and Accrued Liabilities [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	0.7		0.6		8.8
Cash Flow Hedging [Member] | Accounts Payable and Accrued Liabilities [Member] | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	5.1		0.4		3.7
Cash Flow Hedging [Member] | Level 1 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	0.0		0.0		0.0
Cash Flow Hedging [Member] | Level 1 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Collars [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]			0.0		0.0
Cash Flow Hedging [Member] | Level 1 [Member] | Prepaid Expenses and Other Current Assets [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		0.0		0.0
Cash Flow Hedging [Member] | Level 1 [Member] | Prepaid Expenses and Other Current Assets [Member] | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	0.0
Cash Flow Hedging [Member] | Level 1 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	0.0		0.0		0.0
Cash Flow Hedging [Member] | Level 1 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Collars [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value		0.0	[4]	0.0	[4]	0.0
Cash Flow Hedging [Member] | Level 1 [Member] | Accounts Payable and Accrued Liabilities [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		0.0		0.0
Cash Flow Hedging [Member] | Level 1 [Member] | Accounts Payable and Accrued Liabilities [Member] | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	0.0		0.0		0.0
Cash Flow Hedging [Member] | Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	1.9		3.6		6.0
Cash Flow Hedging [Member] | Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Collars [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]			0.4		1.0
Cash Flow Hedging [Member] | Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	3.4		9.6		3.2
Cash Flow Hedging [Member] | Level 2 [Member] | Prepaid Expenses and Other Current Assets [Member] | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	0.9
Cash Flow Hedging [Member] | Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	6.2		5.4		4.3
Cash Flow Hedging [Member] | Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Collars [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	0.3		0.3		0.5
Cash Flow Hedging [Member] | Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member] | Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	0.7		0.6		8.8
Cash Flow Hedging [Member] | Level 2 [Member] | Accounts Payable and Accrued Liabilities [Member] | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	5.1		0.4		3.7
Cash Flow Hedging [Member] | Level 3 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	0.0		0.0		0.0
Cash Flow Hedging [Member] | Level 3 [Member] | Prepaid Expenses and Other Current Assets [Member] | Precious Metal Collars [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]			0.0		0.0
Cash Flow Hedging [Member] | Level 3 [Member] | Prepaid Expenses and Other Current Assets [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		0.0		0.0
Cash Flow Hedging [Member] | Level 3 [Member] | Prepaid Expenses and Other Current Assets [Member] | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value	[3]	0.0
Cash Flow Hedging [Member] | Level 3 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	0.0		0.0		0.0
Cash Flow Hedging [Member] | Level 3 [Member] | Accounts Payable and Accrued Liabilities [Member] | Precious Metal Collars [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value		0.0	[4]	0.0	[4]	0.0
Cash Flow Hedging [Member] | Level 3 [Member] | Accounts Payable and Accrued Liabilities [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		0.0		0.0
Cash Flow Hedging [Member] | Level 3 [Member] | Accounts Payable and Accrued Liabilities [Member] | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value	[4]	$ 0.0		$ 0.0		$ 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.