Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ (256.0)	$ 733.6	$ 1,619.6
Other comprehensive income (loss) before reclassifications	(22.3)	65.5
Pre-tax losses (gains) reclassified from accumulated other comprehensive income	13.7	(8.6)
Tax effects	(2.6)	(2.2)
Total other comprehensive (loss) income	(11.2)	54.7	(57.4)
Ending Balance	(210.9)	(256.0)	733.6
Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(16.6)	14.6
Other comprehensive income (loss) before reclassifications	20.6	(24.5)
Pre-tax losses (gains) reclassified from accumulated other comprehensive income	12.1	(9.9)
Tax effects	(1.1)	3.2
Total other comprehensive (loss) income	31.6	(31.2)
Ending Balance	15.0	(16.6)	14.6
Net Unrealized Gains (Losses) on Available for Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	1.3	1.5
Other comprehensive income (loss) before reclassifications	0.7	(0.6)
Pre-tax losses (gains) reclassified from accumulated other comprehensive income	1.3	0.3
Tax effects	0.0	0.1
Total other comprehensive (loss) income	2.0	(0.2)
Ending Balance	3.3	1.3	1.5
Defined Benefit Pension Components
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(29.3)	(33.8)
Other comprehensive income (loss) before reclassifications	14.7	4.3
Pre-tax losses (gains) reclassified from accumulated other comprehensive income	0.3	0.9
Tax effects	(2.0)	(0.7)
Total other comprehensive (loss) income	13.0	4.5
Ending Balance	(16.3)	(29.3)	(33.8)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(79.2)	(160.8)
Other comprehensive income (loss) before reclassifications	(58.3)	86.3
Pre-tax losses (gains) reclassified from accumulated other comprehensive income	0.0	0.1
Tax effects	0.5	(4.8)
Total other comprehensive (loss) income	(57.8)	81.6
Ending Balance	(137.0)	(79.2)	(160.8)
Accumulated other comprehensive loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(123.8)	(178.5)	(121.1)
Ending Balance	$ (135.0)	$ (123.8)	$ (178.5)