Financial Instruments - Fair Value of Derivative Instruments (Detail) - USD ($) $ in Millions		Jan. 31, 2017		Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency forward contracts not designated as cash flow hedges		$ 369.4		$ 142.4
Net loss expected to be recognized into earnings		733.6		1,619.6	$ 2,219.2	$ 2,261.5
Derivative asset, net		13.3		8.3
Derivative liability, net		10.5		6.4
Net Unrealized Gains (Losses) on Derivative Instruments
Derivatives, Fair Value [Line Items]
Net loss expected to be recognized into earnings		14.6		15.7	$ 42.8
Foreign Exchange Contracts
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency forward contracts not designated as cash flow hedges		270.6		231.6
Designated as Hedging Instrument | Foreign Exchange Contracts | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, net		10.1		3.4
Designated as Hedging Instrument | Foreign Exchange Contracts | Other Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, net	[1]	4.5		3.4
Not Designated as Hedging Instrument | Other assets
Derivatives, Fair Value [Line Items]
Derivative asset, net		3.2		4.9
Not Designated as Hedging Instrument | Other Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, net		$ 6.0	[1]	$ 3.0

[1] Balance Sheet Location Fair Value at January 31, 2017 January 31, 2016Derivative Assets Foreign currency contracts designated as cash flow hedgesPrepaid expenses and other current assets $10.1 $3.4Derivatives not designated as hedging instrumentsPrepaid expenses and other current assets and Other assets 3.2 4.9Total derivative assets $13.3 $8.3Derivative Liabilities Foreign currency contracts designated as cash flow hedgesOther accrued liabilities $4.5 $3.4Derivatives not designated as hedging instrumentOther accrued liabilities 6.0 3.0Total derivative liabilities $10.5 $6.4