Financial Instruments (Derivative Narrative) (Details) - USD ($) $ in Millions	Jul. 31, 2020	Jan. 31, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net gain expected to be recognized in next 24 months	$ (7.1)
Designated as hedging instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	1,180.0	$ 981.3
Derivatives not designated as hedging instruments | Foreign currency contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	$ 182.1	$ 736.2