Summary of Significant Accounting Policies Purchased Technology and Other Intangible Asset Amortization Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Schedule of Finite Lived Intangible Assets Amortization Expense
Amortization of intangible assets	$ 8,716	$ 8,166	$ 6,230
Purchased Technology and Other Intangible Asset
Schedule of Finite Lived Intangible Assets Amortization Expense
Amortization of intangible assets	$ 16,019	$ 15,265	$ 9,828