Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 733.6	$ 1,619.6	$ 2,219.2
Other comprehensive income (loss) before reclassifications	65.5	(47.4)
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	(8.6)	(7.7)
Tax effects	(2.2)	(2.3)
Total other comprehensive income (loss)	54.7	(57.4)	(67.8)
Ending Balance	(256.0)	733.6	1,619.6
Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	14.6	15.7
Other comprehensive income (loss) before reclassifications	(24.5)	7.4
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	(9.9)	(7.4)
Tax effects	3.2	(1.1)
Total other comprehensive income (loss)	(31.2)	(1.1)
Ending Balance	(16.6)	14.6	15.7
Net Unrealized Gains (Losses) on Available for Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	1.5	0.2
Other comprehensive income (loss) before reclassifications	(0.6)	3.3
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	0.3	(1.5)
Tax effects	0.1	(0.5)
Total other comprehensive income (loss)	(0.2)	1.3
Ending Balance	1.3	1.5	0.2
Defined Benefit Pension Components
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(33.8)	(28.3)
Other comprehensive income (loss) before reclassifications	4.3	(5.8)
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	0.9	1.2
Tax effects	(0.7)	(0.9)
Total other comprehensive income (loss)	4.5	(5.5)
Ending Balance	(29.3)	(33.8)	(28.3)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(160.8)	(108.7)
Other comprehensive income (loss) before reclassifications	86.3	(52.3)
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	0.1	0.0
Tax effects	(4.8)	0.2
Total other comprehensive income (loss)	81.6	(52.1)
Ending Balance	(79.2)	(160.8)	(108.7)
Accumulated other comprehensive (loss) income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(178.5)	(121.1)	(53.3)
Ending Balance	$ (123.8)	$ (178.5)	$ (121.1)