Income Taxes (Details) (USD $)	12 Months Ended
	Jan. 26, 2014	Jan. 27, 2013	Jan. 29, 2012
Current Income Tax Expense
Federal	$ 7,896,000	$ 7,506,000	$ 7,099,000
State	1,234,000	1,016,000	789,000
Foreign	18,513,000	16,766,000	7,630,000
Total current	27,643,000	25,288,000	15,518,000
Deferred Income Tax Expense
Federal	17,070,000	28,143,000	25,111,000
State	0	0	0
Foreign	(1,640,000)	3,717,000	(6,055,000)
Total deferred	15,430,000	31,860,000	19,056,000
Charge in lieu of taxes attributable to employer stock option plans	27,191,000	42,355,000	47,732,000
Income tax expense	70,264,000	99,503,000	82,306,000
Income before Income Taxes
Foreign	431,118,000	562,617,000	542,628,000
Domestic	79,136,000	99,422,000	120,768,000
Income before income tax	510,254,000	662,039,000	663,396,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Tax expense computed at federal statutory rate	178,589,000	231,714,000	232,189,000
State income taxes, net of federal tax effect	1,608,000	1,048,000	2,302,000
Foreign tax rate differential	(93,831,000)	(123,626,000)	(142,071,000)
U.S. federal R&D tax credit	(30,155,000)	(29,294,000)	(24,270,000)
Stock-based compensation	8,900,000	11,876,000	10,983,000
Tax expense related to inter-company transaction	9,785,000	9,785,000	1,533,000
Other	(4,632,000)	(2,000,000)	1,640,000
Income tax expense	70,264,000	99,503,000	82,306,000
Components of Deferred Tax Assets [Abstract]
Net operating loss carryforwards	81,629,000	84,156,000
Accruals and reserves, not currently deductible for tax purposes	131,932,000	121,644,000
Property, equipment and intangible assets	48,358,000	54,636,000
Research and other tax credit carryforwards	306,975,000	271,933,000
Stock-based compensation	33,135,000	34,187,000
Convertible debt - DTA	14,885,000	0
Gross deferred tax assets	616,914,000	566,556,000
Less: valuation allowance	(244,487,000)	(224,774,000)
Deferred Tax Assets, Net	372,427,000	341,782,000
Components of Deferred Tax Liabilities [Abstract]
Deferred Tax Liabilities Intangible Assets	(33,244,000)	(43,878,000)
Unremitted earnings of foreign subsidiaries	(425,401,000)	(383,591,000)
Deferred Tax Liabilities, Gross	(458,645,000)	(427,469,000)
Net deferred tax asset (liability)	(86,218,000)	(85,687,000)
Effective tax rate	13.80%	15.00%	12.40%
Operating Loss Carryforwards [Line Items]
Excess Tax Benefit Related To StockBasedCompensation	427,900,000
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	601,800,000
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	716,000,000
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	366,900,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	387,700,000
Undistributed Earnings Of Non United States Subsidiaries	1,960,000,000
Foreign Credit Carryforward to be refunded in 2016	4,700,000
Foreign Credit Carryforward to be refunded in 2017	4,800,000
Foreign Credit Carryforward to be refunded in 2018	6,200,000
GERMANY
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	91,400,000
UNITED KINGDOM
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	250,400,000
CANADA
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	21,000,000
Othe state tax credit carryforward [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Other	3,000,000
Deferred Tax Assets, Tax Credit Carryforwards, Research	11,000,000
California Research Credit [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Research	358,200,000
Other federal tax credit carryforward [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Other	1,500,000
other foreign tax credit carryforward [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Other	15,700,000
State Research Credit [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 369,200,000