CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 228.8	$ 247.4	$ 285.3
Net gain (loss) on derivative instruments (net of tax effect of $1.1, ($0.5) and $1.0)	0.7	(6.4)	10.0
Change in net unrealized (loss) gain on available-for-sale securities (net of tax effect of $0.3, ($0.6) and $0.0)	(1.1)	2.0	0.2
Change in defined benefit pension items (net of tax effect of $0.6, $0.4 and $0.0)	5.4	(6.1)	1.2
Net change in cumulative foreign currency translation gain (loss) (net of tax effect of $2.1, $2.1 and ($4.4))	0.1	(1.1)	(4.9)
Total other comprehensive income (loss)	5.1	(11.6)	6.5
Total comprehensive income	$ 233.9	$ 235.8	$ 291.8