Summary of Significant Accounting Policies Carrying Value of Goodwill, Intangible Assets, and Long-lived Assets - Additional Information (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2015	Jan. 31, 2014
Purchased Technology and In-Process Research and Development
Goodwill And Intangible Assets Disclosure
Intangible assets, accumulated amortization	$ 131,143	$ 124,536
Other Intangible Assets
Goodwill And Intangible Assets Disclosure
Intangible assets, accumulated amortization	$ 78,788	$ 71,216