Derivative Instruments (Narrative) (Details) $ in Millions	12 Months Ended
	Jan. 31, 2020 USD ($)	Jan. 31, 2019 USD ($)	Jan. 31, 2018 USD ($)
Derivative [Line Items]
Net foreign currency loss (gain)	$ 8.3	$ 27.1	$ 32.7
Notional amount of derivative financial instruments outstanding	$ 1,300.0	$ 1,500.0	$ 1,000.0
Average maturities of derivatives, days	25 days	25 days	31 days
Net Investment Hedging [Member]
Derivative [Line Items]
Derivative, Number of Instruments Held		0	0
Cash Flow Hedging [Member]
Derivative [Line Items]
Derivative, Number of Instruments Held		0	0
Derivative, Notional Amount	$ 4.5