Stock-Based Compensation (Schedule of Stock-Based Compensation Expense) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2011	Jul. 31, 2010
Allocated share-based compensation expense	$ 8,344	$ 10,996	$ 19,421	$ 31,753
Product Costs [Member] | Stock Options [Member]
Allocated share-based compensation expense	30	27	127	427
Product Costs [Member] | Restricted/Deferred Stock Awards [Member]
Allocated share-based compensation expense	150	221	322	460
Service Costs [Member] | Stock Options [Member]
Allocated share-based compensation expense	61	344	227	1,523
Service Costs [Member] | Restricted/Deferred Stock Awards [Member]
Allocated share-based compensation expense	590	716	1,235	1,314
Selling, General And Administrative [Member] | Stock Options [Member]
Allocated share-based compensation expense	677	995	2,067	8,217
Selling, General And Administrative [Member] | Restricted/Deferred Stock Awards [Member]
Allocated share-based compensation expense	6,005	7,720	13,597	15,258
Research And Development [Member] | Stock Options [Member]
Allocated share-based compensation expense	143	144	383	2,663
Research And Development [Member] | Restricted/Deferred Stock Awards [Member]
Allocated share-based compensation expense	688	829	1,463	1,891
Stock Options [Member]
Allocated share-based compensation expense	911	1,510	2,804	12,830
Restricted/Deferred Stock Awards [Member]
Allocated share-based compensation expense	$ 7,433	$ 9,486	$ 16,617	$ 18,923