Stock-Based Compensation (Schedule Of Stock-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 9,073	$ 8,231	$ 17,096	$ 19,205
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	305	798	881	2,635
Restricted/Deferred Stock Awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	8,768	7,433	16,215	16,570
Product Costs | Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	5	30	26	125
Product Costs | Restricted/Deferred Stock Awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	187	150	300	322
Service Costs | Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	38	61	113	226
Service Costs | Restricted/Deferred Stock Awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	825	590	1,590	1,235
Research and Development | Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	37	130	114	365
Research and Development | Restricted/Deferred Stock Awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	876	688	1,427	1,463
Selling, General and Administrative | Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	225	577	628	1,919
Selling, General and Administrative | Restricted/Deferred Stock Awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 6,880	$ 6,005	$ 12,898	$ 13,550