Investments (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Oct. 31, 2015	Nov. 01, 2014	Jan. 31, 2015
Available-for-sale securities
Amortized Cost	$ 5,008		$ 18,050
Unrealized Gains	2		5
Unrealized Losses	(1)		(10)
Estimated Fair Value	5,009		18,045
Purchases of available-for-sale securities	0	$ 12,495
Maturities of available-for-sale investments	13,007	10,200
Other than temporary impairment of available-for-sale securities	0	$ 0
Expected maturities of available-for-sale securities
Due in one year or less	5,009
Short Term Investments
Available-for-sale securities
Amortized Cost			13,293
Unrealized Gains			5
Unrealized Losses			(5)
Estimated Fair Value			13,293
Long Term Investments
Available-for-sale securities
Amortized Cost			4,757
Unrealized Losses			(5)
Estimated Fair Value			4,752
Certificates of deposit \| Short Term Investments
Available-for-sale securities
Amortized Cost	480		4,080
Unrealized Losses			(2)
Estimated Fair Value	480		4,078
Commercial paper \| Short Term Investments
Available-for-sale securities
Amortized Cost	1,499		7,384
Unrealized Gains	1		3
Unrealized Losses			(3)
Estimated Fair Value	1,500		7,384
Corporate bonds \| Short Term Investments
Available-for-sale securities
Amortized Cost	2,822		1,615
Unrealized Gains			1
Unrealized Losses	(1)
Estimated Fair Value	2,821		1,616
Corporate bonds \| Long Term Investments
Available-for-sale securities
Amortized Cost			2,857
Unrealized Losses			(4)
Estimated Fair Value			2,853
U.S. Agency securities \| Long Term Investments
Available-for-sale securities
Amortized Cost			1,900
Unrealized Losses			(1)
Estimated Fair Value			1,899
Municipal bonds \| Short Term Investments
Available-for-sale securities
Amortized Cost	207		214
Unrealized Gains	1		1
Estimated Fair Value	$ 208		$ 215

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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