Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,128.4	$ (139.1)	$ 965.5	$ (139.1)
Other comprehensive income (loss) before reclassifications			6.7	6.4
Pre-tax losses reclassified from accumulated other comprehensive loss			9.8	(2.2)
Tax effects			(4.0)	1.6
Total other comprehensive (loss) income	(11.7)	24.6	12.5	5.8
Ending balance	1,327.8	67.3	1,327.8	67.3
Accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(101.7)	(179.1)	(125.9)	(160.3)
Ending balance	(113.4)	(154.5)	(113.4)	(154.5)
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 (loss) before reclassifications			13.3	(15.4)
Pre-tax losses reclassified from accumulated other comprehensive loss			9.6	(2.0)
Tax effects			(3.4)	1.9
Total other comprehensive (loss) income			19.5	(15.5)
Ending balance	(4.6)	(7.1)	(4.6)	(7.1)
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 (loss) before reclassifications			7.8	1.1
Pre-tax losses reclassified from accumulated other comprehensive loss			0.0	0.1
Tax effects			0.0	0.1
Total other comprehensive (loss) income			7.8	1.3
Ending balance	14.2	6.0	14.2	6.0
Defined Benefit Pension Components
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(21.3)	(22.8)
Other comprehensive income (loss) before reclassifications			0.0	0.0
Pre-tax losses reclassified from accumulated other comprehensive loss			0.2	(0.3)
Tax effects			0.0	0.0
Total other comprehensive (loss) income			0.2	(0.3)
Ending balance	(21.1)	(23.1)	(21.1)	(23.1)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(86.9)	(150.6)
Other comprehensive income (loss) before reclassifications			(14.4)	20.7
Pre-tax losses reclassified from accumulated other comprehensive loss			0.0	0.0
Tax effects			(0.6)	(0.4)
Total other comprehensive (loss) income			(15.0)	20.3
Ending balance	$ (101.9)	$ (130.3)	$ (101.9)	$ (130.3)