Income Taxes Tax Effects of Temporary Differences and Carryforwards on Deferred Tax Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2014	Jan. 31, 2013
Deferred Tax Assets, Net [Abstract]
Depreciation of property, plant, and equipment	$ (8)	$ 274
Reserves and allowances	10,733	10,398
Accrued expenses not currently deductible	20,118	20,463
Stock-based compensation expense	7,839	12,394
Net operating loss carryforwards	40,245	55,612
Tax credit carryforwards	90,852	75,639
Purchased technology and other intangible assets	3,267	6,456
Deferred revenue	3,680	3,097
Other, net	4,844	7,853
Total gross deferred tax assets	181,570	192,186
Less valuation allowance	(126,989)	(154,695)
Deferred tax assets	54,581	37,491
Deferred Tax Liabilities, Net [Abstract]
Intangible assets	(5,699)	(8,286)
Undistributed foreign earnings	(32,132)	(1,662)
Convertible debt	11,276	13,519
Deferred tax liabilities	49,107	23,467
Net deferred tax assets	$ 5,474	$ 14,024