Stock-Based Compensation (Schedule Of Stock-Based Compensation Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 7,743	$ 7,572	$ 21,207	$ 25,080
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	86	286	752	2,762
Restricted/Deferred Stock Awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	7,657	7,286	20,455	22,318
Product Costs | Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	0	4	26	122
Product Costs | Restricted/Deferred Stock Awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	257	242	557	564
Service Costs | Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	19	28	108	230
Service Costs | Restricted/Deferred Stock Awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	545	491	1,423	1,445
Research and Development | Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	22	32	132	378
Research and Development | Restricted/Deferred Stock Awards
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	747	625	1,774	1,865
Selling, General and Administrative | Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	45	222	486	2,032
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	$ 6,108	$ 5,928	$ 16,701	$ 18,444