Stock Based Compensation (Details) (USD $)	3 Months Ended		6 Months Ended			12 Months Ended
	Jul. 27, 2014	Jul. 28, 2013	Jul. 27, 2014		Jul. 28, 2013	Jan. 26, 2014
Share-based Compensation
Cost of revenue	$ 2,656,000	$ 2,168,000	$ 5,575,000		$ 4,821,000
Research and development	21,462,000	18,555,000	41,956,000		40,490,000
Sales, general and administrative	14,297,000	11,672,000	26,405,000		20,481,000
Stock based compensation expense	38,415,000	32,395,000	73,936,000		65,792,000
Stock Options granted (in shares)	78,129	500,000	85,929		3,300,000
Weighted average grant-date fair value per option	$ 3.96	$ 2.96	$ 4.02		$ 3.09
RSUs and PSUs granted (in shares)	500,000	700,000	3,729,000	[1]	5,600,000
Weighted average grant-date fair value of RSUs and PSUs	$ 17.68	$ 13.49	$ 17.20		$ 11.93
Stock-based compensation expense related to equity awards not expected to vest	1,600,000	1,800,000	11,500,000		13,700,000
Aggregate amount of unearned stock-based compensation expense related to equity awards, adjusted for estimated forfeitures	235,600,000		235,600,000			241,300,000
Unearned stock-based compensation expense related to stock options weighted average amortization period (in years)	2 years 2 months 12 days					2 years 6 months 0 days
Unearned stock-based compensation expense related to RSUs/PSUs weighted average amortization period (in years)	2 years 7 months 6 days					2 years 8 months 12 days
Stock Options
Stock options beginning balance (in shares)			32,504,000
Stock Options granted (in shares)	78,129	500,000	85,929		3,300,000
Stock options exercised (in shares)			(6,291,000)
Stock options cancelled (in shares)			(942,000)
Stock options ending balance (in shares)	25,357,000		25,357,000			32,504,000
Weighted average exercise price of stock options at beginning of period			$ 14.22
Weighted average exercise price of stock options granted			$ 18.66
Weighted average exercise price of stock options exercised			$ 12.89
Weighted average exercise price of stock options cancelled			$ 18.89
Weighted average exercise price of stock options at end of period	$ 14.39		$ 14.39			$ 14.22
RSUs/PSUs
RSUs/PSUs beginning balance (in shares)			18,852,000
RSUs and PSUs granted (in shares)	500,000	700,000	3,729,000	[1]	5,600,000
RSUs/PSUs vested (in shares)			(3,319,000)
RSUs/PSUs cancelled (in shares)			(793,000)
RSUs/PSUs ending balance (in shares)	18,469,000		18,469,000			18,852,000
Weighted average grant date fair value of RSUs/PSUs at beginning of period			$ 13.82
Weighted average grant-date fair value of RSUs and PSUs	$ 17.68	$ 13.49	$ 17.20		$ 11.93
Weighted average grant-date fair value of RSUs/PSUs vested			$ 13.33
Weighted average grant date fair value of RSUs/PSUs cancelled			$ 13.98
Weighted average grant date fair value of RSUs/PSUs at end of period	$ 14.58		$ 14.58			$ 13.82
Maximum number of PSUs issuable	2,500,000		2,500,000
Minimum number of PSUs issuable	1,400,000		1,400,000
Minimum
Share-based Compensation
Weighted average expected life (in years)	2 years 6 months 0 days	2 years 4 months 24 days	2 years 6 months 0 days		2 years 4 months 24 days
Maximum
Share-based Compensation
Weighted average expected life (in years)	2 years 6 months 0 days	3 years 4 months 24 days	3 years 2 months 12 days		3 years 4 months 24 days
Stock Options
Share-based Compensation
Estimated grant-date fair value	309,400	1,400,000	345,300		10,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Method Used	(Using a binomial model)	(Using a binomial model)	(Using a binomial model)		(Using a binomial model)
Risk free interest rate, minimum (in hundredths)	2.50%	1.80%	2.50%		1.80%
Risk free interest rate, maximum (in hundredths)	2.50%	2.70%	2.80%		2.70%
Volatility rate, minimum (in hundredths)	31.00%	30.00%	31.00%		30.00%
Volatility rate, maximum (in hundredths)	31.00%	33.00%	31.00%		37.00%
Dividend yield minimum	1.80%	2.10%	1.80%		2.10%
Dividend yield maximum	1.80%	2.20%	1.90%		2.40%
RSUs and PSUs
Share-based Compensation
Estimated grant-date fair value	$ 8,400,000	$ 8,900,000	$ 64,100,000		$ 66,300,000
Employee Stock Purchase Plan
Share-based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Method Used	(Using a Black-Scholes model)	(Using a Black-Scholes model)	(Using a Black-Scholes model)		(Using a Black-Scholes model)
Risk free interest rate, minimum (in hundredths)	0.00%	0.00%	0.10%		0.10%
Risk free interest rate, maximum (in hundredths)	0.00%	0.00%	0.30%		0.30%
Volatility rate, minimum (in hundredths)	0.00%	0.00%	31.00%		37.00%
Volatility rate, maximum (in hundredths)	0.00%	0.00%	31.00%		37.00%
Dividend yield minimum	0.00%	0.00%	1.90%		2.40%
Dividend yield maximum	0.00%	0.00%	1.90%		2.40%
Employee Stock Purchase Plan | Minimum
Share-based Compensation
Weighted average expected life (in years)	0 years 0 months 0 days	0 years 0 months 0 days	0 years 6 months 0 days		0 years 6 months 0 days
Employee Stock Purchase Plan | Maximum
Share-based Compensation
Weighted average expected life (in years)	0 years 0 months 0 days	0 years 0 months 0 days	2 years 0 months 0 days		2 years 0 months 0 days

[1] Includes the total number of PSUs issuable if the maximum corporate financial performance target level for fiscal year 2015 is achieved. Depending on the actual level of achievement of the corporate performance goal at the end of fiscal year 2015, the range of PSUs issued could range from 1.4 million to 2.5 million shares.