Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 965.5	$ (139.1)
Other comprehensive income before reclassifications	23.7	(17.1)
Pre-tax losses reclassified from accumulated other comprehensive loss	4.0	(1.4)
Tax effects	(3.5)	(0.3)
Total other comprehensive income (loss)	24.2	(18.8)
Ending balance	1,128.4	(139.1)
Accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(125.9)	(160.3)
Ending balance	(101.7)	(179.1)
Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(24.1)	8.4
Other comprehensive income before reclassifications	7.8	5.6
Pre-tax losses reclassified from accumulated other comprehensive loss	3.9	(1.2)
Tax effects	(1.7)	(0.4)
Total other comprehensive income (loss)	10.0	4.0
Ending balance	(14.1)	12.4
Net Unrealized Gains on Available-for-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	6.4	4.7
Other comprehensive income before reclassifications	4.0	0.2
Pre-tax losses reclassified from accumulated other comprehensive loss	0.0	0.1
Tax effects	0.0	0.1
Total other comprehensive income (loss)	4.0	0.4
Ending balance	10.4	5.1
Defined Benefit Pension Components
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(21.3)	(22.8)
Other comprehensive income before reclassifications	0.0	0.0
Pre-tax losses reclassified from accumulated other comprehensive loss	0.1	(0.3)
Tax effects	0.0	0.0
Total other comprehensive income (loss)	0.1	(0.3)
Ending balance	(21.2)	(23.1)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(86.9)	(150.6)
Other comprehensive income before reclassifications	11.9	(22.9)
Pre-tax losses reclassified from accumulated other comprehensive loss	0.0	0.0
Tax effects	(1.8)	0.0
Total other comprehensive income (loss)	10.1	(22.9)
Ending balance	$ (76.8)	$ (173.5)