Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Jan. 26, 2014	Jan. 27, 2013	Jan. 29, 2012	Jan. 30, 2011
Accounting Policies [Abstract]
Excess Tax Benefit Related To StockBasedCompensation	$ 427,900,000
Deferred Tax Assets, Valuation Allowance	244,487,000	224,774,000
Advertising Expense	13,100,000	9,200,000	8,400,000
Foreign Currency Transaction Gain (Loss), Realized	4,700,000	(1,500,000)	1,600,000
Asset Retirement Obligation	11,100,000	10,600,000
Summary of cash equivalents and marketable securities:
Amortized Cost	4,087,893,000	3,286,436,000
Cash and cash equivalents	1,151,587,000	732,786,000	667,876,000	665,361,000
Percentage of accounts receivable from significant customers	0.23
Money Market Funds
Summary of cash equivalents and marketable securities:
Amortized Cost	$ 307,865,000	$ 195,790,000
Customer A (AR)
Summary of cash equivalents and marketable securities:
Percentage of accounts receivable from significant customers	0.23	0.20