Hedging Instruments - Information on Location and Amounts of Derivative Gains and Losses in Consolidated Financial Statements (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Cost of sales	$ 383.9	$ 382.3
Interest expense and financing costs	10.4	9.9
Other (income) expense, net	(1.0)	3.9
Other comprehensive loss, net of tax	(13.2)	(29.9)
Unrealized gain (loss) on hedging instruments	17.7	(7.2)
Cash Flow Hedging | Foreign Exchange Forward | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	0.0	0.0
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	(1.1)	(1.6)
Cash Flow Hedging | Foreign Exchange Forward | Interest expense and financing costs
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	0.0	0.0
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Foreign Exchange Forward | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	0.0	0.0
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Foreign Exchange Forward | Other comprehensive loss, net of tax
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	5.7	1.8
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	1.1	1.6
Cash Flow Hedging | Precious Metal Collars | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	(0.1)	(0.1)
Cash Flow Hedging | Precious Metal Collars | Interest expense and financing costs
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Precious Metal Collars | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Precious Metal Collars | Other comprehensive loss, net of tax
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.1	0.1
Cash Flow Hedging | Precious Metal Forward Contracts | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	0.0	0.0
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	1.1	(0.4)
Cash Flow Hedging | Precious Metal Forward Contracts | Interest expense and financing costs
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	0.0	0.0
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Precious Metal Forward Contracts | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	0.0	0.0
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Precious Metal Forward Contracts | Other comprehensive loss, net of tax
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	(1.4)	(5.6)
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	(1.1)	0.4
Cash Flow Hedging | Currency Swap | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	0.0	0.0
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Currency Swap | Interest expense and financing costs
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	0.0	0.0
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Currency Swap | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	0.0	0.0
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	(7.8)	(0.6)
Cash Flow Hedging | Currency Swap | Other comprehensive loss, net of tax
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on hedging instruments	13.4	(3.4)
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	7.8	0.6
Cash Flow Hedging | Interest Rate Swap | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Interest Rate Swap | Interest expense and financing costs
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.3	0.4
Cash Flow Hedging | Interest Rate Swap | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	0.0	0.0
Cash Flow Hedging | Interest Rate Swap | Other comprehensive loss, net of tax
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) reclassified from accumulated OCI into earnings	$ (0.3)	$ (0.4)