Hedging Instruments - Additional Information (Details) $ in Millions	12 Months Ended
	Jan. 31, 2016 USD ($) oz	Jan. 31, 2015 USD ($)	Jan. 31, 2014 USD ($)	Jan. 31, 2013 USD ($)
Derivative [Line Items]
Payment for settlement of interest rate swaps	$ 0.0	$ 4.2	$ 0.0
Expected approximately amount of net pre-tax derivative losses included in accumulated other comprehensive income that will be reclassified into earnings within the next 12 months	$ 7.8
Platinum [Member]
Derivative [Line Items]
Notional amount of precious metal hedge (in ounces) | oz	72,000
Silver [Member]
Derivative [Line Items]
Notional amount of precious metal hedge (in ounces) | oz	1,440,000
Gold [Member]
Derivative [Line Items]
Notional amount of precious metal hedge (in ounces) | oz	50,000
Maximum [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Term of Contract	12 months
Maximum [Member] | Precious Metal Forward Contracts [Member]
Derivative [Line Items]
Derivative, Term of Contract	24 months
2012 4.40% Series B Notes, due July 2042 [Member]
Derivative [Line Items]
Debt Instrument, Face Amount				$ 250.0
2014 3.80% Senior Notes, due October 2024 [Member]
Derivative [Line Items]
Debt Instrument, Face Amount	$ 250.0
2014 4.90% Senior Notes, due October 2044 [Member]
Derivative [Line Items]
Debt Instrument, Face Amount	300.0
2012 Debt Issuance [Member] | Forward-starting Interest Rate Swaps [Member]
Derivative [Line Items]
Unrealized loss on interest rate swaps	21.1
2014 Debt Issuance [Member] | Forward-starting Interest Rate Swaps [Member]
Derivative [Line Items]
Unrealized loss on interest rate swaps	$ 4.0
Other expense (income), net [Domain] | Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net		$ 10.5