Summary of Investments (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 28, 2012	Jan. 28, 2012
Gain (Loss) on Investments [Line Items]
Amortized Cost	$ 1,243,010	$ 1,482,394
Gross Unrealized Gains	4,649	4,521
Gross Unrealized Losses	(1,471)	(2,104)
Estimated Fair Value	1,246,188	1,484,811
Short-term Investments
Gain (Loss) on Investments [Line Items]
Amortized Cost	1,223,510	1,457,894
Gross Unrealized Gains	4,649	4,521
Gross Unrealized Losses	(74)	(819)
Estimated Fair Value	1,228,085	1,461,596
Short-term Investments | Available-for-sale | Corporate debt securities
Gain (Loss) on Investments [Line Items]
Amortized Cost	612,749	685,563
Gross Unrealized Gains	3,775	3,081
Gross Unrealized Losses	(55)	(799)
Estimated Fair Value	616,469	687,845
Short-term Investments | Available-for-sale | Foreign Government
Gain (Loss) on Investments [Line Items]
Amortized Cost	2,026	2,033
Gross Unrealized Gains	10	3
Estimated Fair Value	2,036	2,036
Short-term Investments | Available-for-sale | U.S. Federal and State debt securities
Gain (Loss) on Investments [Line Items]
Amortized Cost	608,735	770,298
Gross Unrealized Gains	864	1,437
Gross Unrealized Losses	(19)	(20)
Estimated Fair Value	609,580	771,715
Long-term investments
Gain (Loss) on Investments [Line Items]
Amortized Cost	19,500	24,500
Gross Unrealized Losses	(1,397)	(1,285)
Estimated Fair Value	18,103	23,215
Long-term investments | Auction rate securities
Gain (Loss) on Investments [Line Items]
Gross Unrealized Losses	(1,400)
Long-term investments | Available-for-sale | Auction rate securities
Gain (Loss) on Investments [Line Items]
Amortized Cost	19,500	24,500
Gross Unrealized Losses	(1,397)	(1,285)
Estimated Fair Value	$ 18,103	$ 23,215