Revenue Recognition (Narrative) (Details) $ in Millions	3 Months Ended
	Apr. 30, 2020 USD ($) category	Apr. 30, 2019 USD ($)
Revenue from Contract with Customer [Abstract]
Number of revenue categories | category	3
Remaining performance obligation	$ 3,470.0
Contract with customer, liability, revenue recognized	787.2	$ 643.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-05-01
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 2,350.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation percentage	68.00%
Performance obligation, expected timing of satisfaction	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-02-01
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 1,120.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation percentage	32.00%
Performance obligation, expected timing of satisfaction	3 years