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		9 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
Significant Unobservable Inputs (Level 3)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance, Asset	$ 0	$ 52,612	$ 272	$ 73,163
Sales and redemptions, Asset	0	(250)	(394)	(25,750)
Change in realized and unrealized gains included in other expense, net, Asset	0	120	156	8,011
Change in unrealized losses included in other comprehensive income, Asset	0	(1,463)	(34)	(4,443)
Change In fair value recorded in operating expenses, Asset	0	20	0	58
Ending balance, Asset	0	51,039	0	51,039
Beginning balance, Liability	25,204	2,364	38,646	3,686
Contingent consideration liability recorded for business combination, Liability	0	32,800	0	33,704
Payments of contingent consideration, Liability	1,000	0	6,902	(4,107)
Change in fair value recorded in operating expenses, Liability	(888)	(541)	(8,428)	1,340
Ending balance, Liability	$ 23,316	$ 34,623	$ 23,316	$ 34,623