Summary of Investments Gross Unrealized Losses and Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 28, 2012	Jan. 28, 2012
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	$ 128,081	$ 254,566
Less than 12 months Unrealized Losses	(51)	(819)
12 months or more Fair Value	22,955	23,215
12 months or more Unrealized Losses	(1,420)	(1,285)
Total Fair Value	151,036	277,781
Total Unrealized Losses	(1,471)	(2,104)
Corporate debt securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	36,290	146,963
Less than 12 months Unrealized Losses	(32)	(799)
12 months or more Fair Value	4,852
12 months or more Unrealized Losses	(23)
Total Fair Value	41,142	146,963
Total Unrealized Losses	(55)	(799)
U.S. Federal and State debt securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 months Fair Value	91,791	107,603
Less than 12 months Unrealized Losses	(19)	(20)
Total Fair Value	91,791	107,603
Total Unrealized Losses	(19)	(20)
Auction rate securities
Investments, Unrealized Loss Position [Line Items]
12 months or more Fair Value	18,103	23,215
12 months or more Unrealized Losses	(1,397)	(1,285)
Total Fair Value	18,103	23,215
Total Unrealized Losses	$ (1,397)	$ (1,285)