CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014	Jul. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 31.3	$ 61.7	$ 59.6	$ 117.3
Other comprehensive income, net of reclassifications:
Net gain (loss) on derivative instruments (net of tax effect of ($0.4), $0.0, ($1.1) and $0.2)	1.8	(5.0)	(1.5)	4.9
Change in net unrealized loss on available-for-sale securities (net of tax effect of $0.4, ($0.1), $0.0 and $0.1)	(1.0)	(1.3)	(1.6)	(1.1)
Net change in cumulative foreign currency translation (loss) gain (net of tax effect of $0.9, $0.5, ($0.4) and $1.8)	(4.1)	0.8	6.0	(5.6)
Total other comprehensive (loss) gain	(3.3)	(5.5)	2.9	(1.8)
Total comprehensive income	$ 28.0	$ 56.2	$ 62.5	$ 115.5