Summary of Significant Accounting Policies Carrying Value of Goodwill, Intangible Assets, and Long-lived Assets (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Goodwill And Intangible Assets Disclosure [Line Items]
Goodwill	$ 535,932	$ 527,102	$ 510,508
Intangible Assets, Net	21,838	28,569
Purchased Techonology and In Process Research and Development [Member]
Goodwill And Intangible Assets Disclosure [Line Items]
Intangible Assets, Net	8,019	14,023
Other Intangible Assets [Member]
Goodwill And Intangible Assets Disclosure [Line Items]
Intangible Assets, Net	$ 13,819	$ 14,546