Summary of Significant Accounting Policies Aggregate Amortization Expense Related to Purchased Technology and Other Intangible Assets (Details) - Purchased Technology and Other Intangible Asset $ in Thousands	Jan. 31, 2016 USD ($)
Goodwill And Intangible Assets Disclosure
Expected amortization expense, year 1	$ 12,889
Expected amortization expense, year 2	11,316
Expected amortization expense, year 3	9,559
Expected amortization expense, year 4	3,077
Expected amortization expense, year 5	548
Expected amortization expense, thereafter	57
Finite lived intangible assets future amortization	$ 37,446