Summary of Significant Accounting Policies Aggregate Amortization Expense Related to Purchased Technology and Other Intangible Assets (Details) (Purchased Technology and Other Intangible Asset, USD $) In Thousands, unless otherwise specified	Jan. 31, 2015
Purchased Technology and Other Intangible Asset
Goodwill And Intangible Assets Disclosure
Expected amortization expense, year 1	$ 14,418
Expected amortization expense, year 2	11,270
Expected amortization expense, year 3	9,584
Expected amortization expense, year 4	7,970
Expected amortization expense, year 5	2,063
Expected amortization expense, thereafter	272
Finite lived intangible assets future amortization	$ 45,577