Fair Value Measurements (Schedule Of Changes In The Fair Value Of The Level 3 Financial Assets And Liabilities) (Details) (Significant Unobservable Inputs (Level 3), USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011
Significant Unobservable Inputs (Level 3)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance, Asset	$ 0	$ 73,185	$ 272	$ 73,163
Sales and redemptions, Asset	0	(25,300)	(394)	(25,500)
Change in realized and unrealized gains included in other expense, net, Asset	0	7,796	156	7,891
Change in unrealized losses included in other comprehensive income, Asset	0	(3,076)	(34)	(2,980)
Change In fair value recorded in operating expenses, Asset	0	7	0	38
Ending balance, Asset	0	52,612	0	52,612
Beginning balance, Liability	33,900	4,613	38,646	3,686
Contingent consideration liability recorded for business combination, Liability	0	0	0	904
Payments of contingent consideration, Liability	(4,152)	(2,107)	(5,902)	(4,107)
Change in fair value recorded in operating expenses, Liability	(4,544)	(142)	(7,540)	1,881
Ending balance, Liability	$ 25,204	$ 2,364	$ 25,204	$ 2,364