Hedging Instruments - Information on Location and Amounts of Derivative Gains and Losses in Consolidated Financial Statements (Detail) (Cash Flow Hedging [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 30, 2015		Apr. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Pre-Tax Gain (Loss) Gain Recognized in OCI (Effective Portion)	$ (4.1)		$ 0.3
Gain (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion)	2.8		5.5
Foreign Exchange Contract [Member] | Cost of sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pre-Tax Gain (Loss) Gain Recognized in OCI (Effective Portion)	1.0		(0.1)
Gain (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion)	4.2	[1]	7.4	[1]
Precious Metal Forward Contracts [Member] | Cost of sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pre-Tax Gain (Loss) Gain Recognized in OCI (Effective Portion)	(5.1)		0.4
Gain (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion)	(1.0)	[1]	(1.5)	[1]
Forward-starting interest rate swaps [Member] | Interest expense and financing costs [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pre-Tax Gain (Loss) Gain Recognized in OCI (Effective Portion)	0		0
Gain (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion)	$ (0.4)	[2]	$ (0.4)	[2]

[1] The gain or loss recognized in earnings is included within Cost of sales.

[2] The gain or loss recognized in earnings is included within Interest and other expenses, net.