Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 1,619.6	$ 2,219.2	$ 2,261.5
Total other comprehensive loss	(57.4)	(67.8)	(52.7)
Ending Balance	733.6	1,619.6	2,219.2
Accumulated other comprehensive (loss) income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(121.1)	(53.3)	(0.6)
Other comprehensive income (loss) before reclassifications	(47.4)	(41.7)
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	(7.7)	(28.1)
Tax effects	(2.3)	2.0
Total other comprehensive loss	(57.4)	(67.8)
Ending Balance	(178.5)	(121.1)	(53.3)
Net Unrealized Gains (Losses) on Derivative Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	15.7	42.8
Other comprehensive income (loss) before reclassifications	7.4	1.6
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	(7.4)	(29.3)
Tax effects	(1.1)	0.6
Total other comprehensive loss	(1.1)	(27.1)
Ending Balance	14.6	15.7	42.8
Net Unrealized Gains (Losses) on Available for Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	0.2	1.6
Other comprehensive income (loss) before reclassifications	3.3	(1.3)
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	(1.5)	(0.1)
Tax effects	(0.5)	0.0
Total other comprehensive loss	1.3	(1.4)
Ending Balance	1.5	0.2	1.6
Defined Benefit Pension Components
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(28.3)	(23.7)
Other comprehensive income (loss) before reclassifications	(5.8)	(6.8)
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	1.2	1.3
Tax effects	(0.9)	0.9
Total other comprehensive loss	(5.5)	(4.6)
Ending Balance	(33.8)	(28.3)	(23.7)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(108.7)	(74.0)
Other comprehensive income (loss) before reclassifications	(52.3)	(35.2)
Pre-tax (gains) losses reclassified from accumulated other comprehensive income	0.0	0.0
Tax effects	0.2	0.5
Total other comprehensive loss	(52.1)	(34.7)
Ending Balance	$ (160.8)	$ (108.7)	$ (74.0)