Hedging Instruments - Additional Information (Details) $ in Millions		3 Months Ended
		Apr. 30, 2016 USD ($) oz	Apr. 30, 2015 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Expected approximate amount of net pre-tax derivative losses included in accumulated other comprehensive income that will be reclassified into earnings within the next 12 months		$ (16.6)
Platinum [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of precious metal hedge (in ounces) | oz		72,000
Silver [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of precious metal hedge (in ounces) | oz		1,440,000
Gold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of precious metal hedge (in ounces) | oz		42,500
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		24 months
2012 4.40% Series B Notes, due July 2042 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Debt Instrument, Face Amount		$ 250.0
2012 Debt Issuance [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized loss on interest rate swaps		20.8
2014 Debt Issuance [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized loss on interest rate swaps		3.9
Interest and other expenses, net [Domain] | Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Loss on Derivative	[1]	$ 5.8	$ 4.8

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