Hedging Instruments - Additional Information (Details)	3 Months Ended		6 Months Ended
	Jul. 31, 2020 USD ($) oz	Jul. 31, 2019 USD ($)	Jul. 31, 2020 USD ($) oz		Jul. 31, 2019 USD ($)	Jul. 31, 2012 USD ($)
Derivative [Line Items]
Net gains reclassified from AOCI			$ 4,200,000
Net pre-tax derivative gains and losses			7,900,000
2012 4.40% Series B Notes, due July 2012
Derivative [Line Items]
Debt instrument face amount						$ 250,000,000.0
Forward-starting interest rate swaps | 2012 Debt Issuance
Derivative [Line Items]
Unrealized loss on interest rate swaps	$ 15,500,000		15,500,000
Forward-starting interest rate swaps | 2014 Debt Issuance
Derivative [Line Items]
Unrealized loss on interest rate swaps	$ 3,200,000		$ 3,200,000
Foreign exchange forward contracts | Maximum
Derivative [Line Items]
Term of contract (months)			12 months
Precious metal forward contracts
Derivative [Line Items]
Reclassified deferred hedging gains resulting from discontinuance of cash flow hedge			$ 4,200,000
Precious metal forward contracts | Maximum
Derivative [Line Items]
Term of contract (months)			18 months
Platinum
Derivative [Line Items]
Precious metal derivatives, ounces outstanding (ounces) | oz	24,900		24,900
Silver
Derivative [Line Items]
Precious metal derivatives, ounces outstanding (ounces) | oz	422,000		422,000
Silver | Not Designated as Hedging Instrument
Derivative [Line Items]
Precious metal derivatives, ounces outstanding (ounces) | oz	24,500		24,500
Gold
Derivative [Line Items]
Precious metal derivatives, ounces outstanding (ounces) | oz	74,500		74,500
Gold | Not Designated as Hedging Instrument
Derivative [Line Items]
Precious metal derivatives, ounces outstanding (ounces) | oz	5,400		5,400
Other income, net | Not Designated as Hedging Instrument
Derivative [Line Items]
Pre-tax gains on derivatives not designated as hedging instruments	$ 8,300,000
Cash Flow Hedging | Cost of sales | Forward-starting interest rate swaps
Derivative [Line Items]
Pre-tax gains on derivatives not designated as hedging instruments	0	$ 0	$ 0		$ 0
Cash Flow Hedging | Cost of sales | Foreign exchange forward contracts
Derivative [Line Items]
Pre-tax gains on derivatives not designated as hedging instruments	(700,000)	(1,400,000)	(1,100,000)		(2,500,000)
Cash Flow Hedging | Cost of sales | Precious metal forward contracts
Derivative [Line Items]
Pre-tax gains on derivatives not designated as hedging instruments	(900,000)	1,100,000	(5,500,000)	[1]	2,200,000
Cash Flow Hedging | Other income, net | Forward-starting interest rate swaps
Derivative [Line Items]
Pre-tax gains on derivatives not designated as hedging instruments	0	0	0		0
Cash Flow Hedging | Other income, net | Foreign exchange forward contracts
Derivative [Line Items]
Pre-tax gains on derivatives not designated as hedging instruments	0	0	0		0
Cash Flow Hedging | Other income, net | Precious metal forward contracts
Derivative [Line Items]
Pre-tax gains on derivatives not designated as hedging instruments	$ 0	$ 0	$ 0	[1]	$ 0

[1] Includes net gains of $4.2 million in the six months ended July 31, 2020 reclassified from Accumulated OCI into Cost of sales on the Condensed Consolidated Statement of Earnings as a result of the discontinuation of hedge accounting on certain precious metal forward contracts.