Hedging Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Expected approximately amount of net pre-tax derivative gains included in accumulated other comprehensive income that will be reclassified into earnings within the next 12 months	$ 9.9
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	84.7
Foreign Exchange Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	156.5
Platinum [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of precious metal hedge (in ounces)	29,100
Silver [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of precious metal hedge (in ounces)	498,200
Gold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of precious metal hedge (in ounces)	40,100
Maximum [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Term of Contract	12 months
Maximum [Member] | Precious Metal Forward Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Term of Contract	12 months
2012 4.40% Series B Notes, due July 2042 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Debt Instrument, Face Amount	250.0
Other income, net [Domain] | Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 4.8	[1]

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