Income Taxes Tax Effects of Temporary Differences and Carryforwards on Deferred Tax Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2015	Jan. 31, 2014
Disclosure Tax Effects Of Temporary Differences and Carryforwards On Deferred Tax Assets and Liabilities [Abstract]
Net deferred tax (liabilities) assets	$ (4,695)us-gaap_DeferredTaxAssetsLiabilitiesNet	$ 5,474us-gaap_DeferredTaxAssetsLiabilitiesNet
Deferred Tax Assets, Net [Abstract]
Reserves and allowances	11,188	10,733
Accrued expenses not currently deductible	21,475	20,118
Stock-based compensation expense	6,988	7,839
Net operating loss carryforwards	34,618	40,245
Tax credit carryforwards	74,235	90,852
Purchased technology and other intangible assets	3,047	3,267
Deferred revenue	2,002us-gaap_DeferredTaxAssetsDeferredIncome	3,680us-gaap_DeferredTaxAssetsDeferredIncome
Other, net	6,762us-gaap_DeferredTaxAssetsOther	4,844us-gaap_DeferredTaxAssetsOther
Total gross deferred tax assets	160,315us-gaap_DeferredTaxAssetsGross	181,578us-gaap_DeferredTaxAssetsGross
Less valuation allowance	(91,956)	(126,989)
Deferred tax assets	68,359us-gaap_DeferredTaxAssetsNet	54,589us-gaap_DeferredTaxAssetsNet
Deferred Tax Liabilities, Net [Abstract]
Intangible assets	(12,976)	(5,699)
Undistributed foreign earnings	(50,163)	(32,132)
Convertible debt	(8,918)	(11,276)
Deferred Tax Liabilities, Property, Plant and Equipment	(997)	(8)
Deferred Tax Liabilities, Gross	$ 73,054us-gaap_DeferredIncomeTaxLiabilities	$ 49,115us-gaap_DeferredIncomeTaxLiabilities

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

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