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, 2017 USD ($)
Goodwill And Intangible Assets Disclosure
Expected amortization expense, year 1	$ 12,845
Expected amortization expense, year 2	11,192
Expected amortization expense, year 3	4,432
Expected amortization expense, year 4	1,842
Expected amortization expense, year 5	1,102
Expected amortization expense, thereafter	400
Finite lived intangible assets future amortization	$ 31,813