Summary of Significant Accounting Policies Purchased Technology and Other Intangible Asset Amortization Expenses (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Schedule of Finite Lived Intangible Assets Amortization Expense [Line Items]
Amortization of intangible assets	$ 5,915	$ 5,905	$ 7,347
Purchased Technology and Other Intangible Asset [Member]
Schedule of Finite Lived Intangible Assets Amortization Expense [Line Items]
Amortization of intangible assets	$ 13,716	$ 15,701	$ 21,118