Investments (Details) (USD $)	3 Months Ended
	May 02, 2015	Jan. 31, 2015	May 03, 2014
Schedule of Investments, Reported Amounts, by Category [Line Items]
Short-term investments	$ 128,705,000	$ 171,201,000	$ 179,877,000
Long-term investments	120,724,000	216,756,000	235,411,000
Current available for sale Securities Unrecognized Holding Gain	38,000
Long-Term Available for Sale Securities Unrecognized Holding Gain	38,000
Current Available for Sale Securities Unrecognized Holding Loss	(112,000)
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss), Net of Tax	(325,000)
Investment disclosure [Abstract]
Gross unrealized gains on short-term investments	0	117,000	107,000
Current Held to Maturity Securities Unrecognized Holding Loss	0	(50,000)	(56,000)
Gross unrealized gains from long-term held-to-maturity investments	0	371,000	575,000
Gross unrealized losses on long-term held-to-maturity investments	0	(317,000)	(269,000)
Short-term investments (a)	128,705,000	171,268,000	179,928,000
Long-term investments (a)	120,724,000	216,810,000	235,717,000
Amortized cost basis | Available-for-sale Securities [Member]
Schedule of Investments, Reported Amounts, by Category [Line Items]
Short-term investments	128,779,000	17,147,000	0
Long-term investments	121,011,000	0	0
Amortized cost basis | Held-to-maturity Securities [Member]
Schedule of Investments, Reported Amounts, by Category [Line Items]
Short-term investments	0	154,054,000	179,877,000
Long-term investments	$ 0	$ 216,756,000	$ 235,411,000