CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 28.3	$ 55.6
Other comprehensive income, net of reclassifications:
Net (loss) gain on derivative instruments (net of tax effect of ($0.7) and $0.2)	(3.3)	9.9
Change in net unrealized (loss) gain on available-for-sale securities (net of tax effect of ($0.4) and $0.2)	(0.6)	0.2
Net change in cumulative foreign currency translation gain (loss) (net of tax effect of ($1.4) and $1.4)	10.1	(6.4)
Total other comprehensive gain	6.2	3.7
Total comprehensive income	$ 34.5	$ 59.3