Summary of Significant Accounting Policies Carrying Value of Goodwill, Intangible Assets, and Long-lived Assets (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Goodwill And Intangible Assets Disclosure
Goodwill	$ 549,044	$ 535,932	$ 527,102
Intangible assets, net	22,799	21,838
Purchased Technology and In-Process Research and Development
Goodwill And Intangible Assets Disclosure
Intangible assets, net	11,210	8,019
Other Intangible Assets
Goodwill And Intangible Assets Disclosure
Intangible assets, net	$ 11,589	$ 13,819