Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended
	Jul. 29, 2012	Jul. 31, 2011	Jul. 29, 2012	Jul. 31, 2011	Jan. 29, 2012
Revenue by Operating Segment and Geographic Region
Revenue	$ 1,044,270,000	$ 1,016,517,000	$ 1,969,147,000	$ 1,978,556,000
Depreciation and amortization expense	56,195,000	52,160,000	110,686,000	99,923,000
Operating income (loss)	139,623,000	174,030,000	212,449,000	328,892,000
Revenue from significant customers (in percent)	12.00%	11.00%	11.00%	11.00%
Number of customers with significant revenue	1	1	1	1
Accounts receivable from significant customers (in percent)	16.00%		16.00%		20.00%
Number of customers with significant accounts receivable balance	1		1		1
Charitable contribution	25,000,000		25,000,000
Net present value, charitable contribution	20,100,000
China [Member]
Revenue by Operating Segment and Geographic Region
Revenue	196,687,000	232,732,000	375,297,000	522,216,000
Taiwan [Member]
Revenue by Operating Segment and Geographic Region
Revenue	340,144,000	281,609,000	616,463,000	564,546,000
Other Asia Pacific [Member]
Revenue by Operating Segment and Geographic Region
Revenue	212,367,000	205,524,000	391,044,000	338,111,000
United States [Member]
Revenue by Operating Segment and Geographic Region
Revenue	154,814,000	153,171,000	300,756,000	262,489,000
Other Americas [Member]
Revenue by Operating Segment and Geographic Region
Revenue	81,260,000	68,224,000	157,082,000	143,354,000
Europe [Member]
Revenue by Operating Segment and Geographic Region
Revenue	58,998,000	75,257,000	128,505,000	147,840,000
GPU [Member]
Revenue by Operating Segment and Geographic Region
Revenue	668,298,000	638,544,000	1,248,019,000	1,276,133,000
Depreciation and amortization expense	32,554,000	30,663,000	64,130,000	59,691,000
Operating income (loss)	162,644,000	139,708,000	241,592,000	259,990,000
PSB [Member]
Revenue by Operating Segment and Geographic Region
Revenue	196,326,000	210,289,000	408,970,000	412,130,000
Depreciation and amortization expense	4,446,000	5,869,000	8,831,000	11,987,000
Operating income (loss)	86,838,000	69,863,000	182,625,000	139,748,000
CPB [Member]
Revenue by Operating Segment and Geographic Region
Revenue	179,646,000	167,684,000	312,158,000	290,293,000
Depreciation and amortization expense	19,195,000	15,628,000	37,725,000	28,245,000
Operating income (loss)	(89,732,000)	(35,541,000)	(191,641,000)	(70,846,000)
All Other [Member]
Revenue by Operating Segment and Geographic Region
Revenue	0	0	0	0
Depreciation and amortization expense	0	0	0	0
Operating income (loss)	$ (20,127,000)	$ 0	$ (20,127,000)	$ 0