Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ (256.0)
Other comprehensive income (loss) before reclassifications			(28.8)
Pre-tax losses reclassified from accumulated other comprehensive loss			4.5
Tax effects			(2.8)
Total other comprehensive (loss) income	$ (17.1)	$ 13.4	(27.1)	$ 25.6
Ending balance	(241.6)		(241.6)
Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(16.6)
Other comprehensive income (loss) before reclassifications			15.1
Pre-tax losses reclassified from accumulated other comprehensive loss			4.3
Tax effects			(1.8)
Total other comprehensive (loss) income			17.6
Ending balance	1.0		1.0
Net Unrealized Gains (Losses) on Available-for-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			1.3
Other comprehensive income (loss) before reclassifications			(0.7)
Pre-tax losses reclassified from accumulated other comprehensive loss			0.0
Tax effects			0.0
Total other comprehensive (loss) income			(0.7)
Ending balance	0.6		0.6
Defined Benefit Pension Components
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(29.3)
Other comprehensive income (loss) before reclassifications			11.3
Pre-tax losses reclassified from accumulated other comprehensive loss			0.2
Tax effects			(1.5)
Total other comprehensive (loss) income			10.0
Ending balance	(19.3)		(19.3)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(79.2)
Other comprehensive income (loss) before reclassifications			(54.5)
Pre-tax losses reclassified from accumulated other comprehensive loss			0.0
Tax effects			0.5
Total other comprehensive (loss) income			(54.0)
Ending balance	(133.2)		(133.2)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(123.8)
Ending balance	$ (150.9)		$ (150.9)