Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 733.6
Total other comprehensive income (loss)	$ 13.4	$ (8.3)	25.6	$ (8.7)
Ending balance	315.5		315.5
Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			14.6
Other comprehensive (loss) income before reclassifications			(12.8)
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			(1.6)
Tax effects			1.4
Total other comprehensive income (loss)			(13.0)
Ending balance	1.6		1.6
Net Unrealized Gains (Losses) on Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			1.5
Other comprehensive (loss) income before reclassifications			0.1
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			0.0
Tax effects			0.1
Total other comprehensive income (loss)			0.2
Ending balance	1.7		1.7
Defined Benefit Pension Components
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(33.8)
Other comprehensive (loss) income before reclassifications			(0.1)
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			(0.1)
Tax effects			0.0
Total other comprehensive income (loss)			(0.2)
Ending balance	(34.0)		(34.0)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(160.8)
Other comprehensive (loss) income before reclassifications			39.4
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			0.1
Tax effects			(0.9)
Total other comprehensive income (loss)			38.6
Ending balance	(122.2)		(122.2)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(178.5)
Other comprehensive (loss) income before reclassifications			26.6
Pre-tax (gains) losses reclassified from accumulated other comprehensive loss			(1.6)
Tax effects			0.6
Total other comprehensive income (loss)			25.6
Ending balance	$ (152.9)		$ (152.9)