Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (139.1)	$ (245.3)	$ (139.1)	$ (210.9)
Other comprehensive (loss) income before reclassifications			6.4
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			(2.2)
Tax effects			1.6
Total other comprehensive income (loss)	24.6	(29.1)	5.8	(35.7)
Ending balance	67.3	(194.3)	67.3	(194.3)
Accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(179.1)	(141.6)	(160.3)	(135.0)
Ending balance	(154.5)	$ (170.7)	(154.5)	$ (170.7)
Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			8.4
Other comprehensive (loss) income before reclassifications			(15.4)
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			(2.0)
Tax effects			1.9
Total other comprehensive income (loss)			(15.5)
Ending balance	(7.1)		(7.1)
Net Unrealized Gains (Losses) on Available-for-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			4.7
Other comprehensive (loss) income before reclassifications			1.1
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			0.1
Tax effects			0.1
Total other comprehensive income (loss)			1.3
Ending balance	6.0		6.0
Defined Benefit Pension Components
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(22.8)
Other comprehensive (loss) income before reclassifications			0.0
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			(0.3)
Tax effects			0.0
Total other comprehensive income (loss)			(0.3)
Ending balance	(23.1)		(23.1)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(150.6)
Other comprehensive (loss) income before reclassifications			20.7
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			0.0
Tax effects			(0.4)
Total other comprehensive income (loss)			20.3
Ending balance	$ (130.3)		$ (130.3)