Fair Value of Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended
	Apr. 29, 2017	Apr. 30, 2016	Jan. 28, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Transfers out of Level 1 into Level 2	$ 0	$ 0
Transfers out of Level 2 into Level 1	0	0
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value measurement, purchases, sales, issuances, or settlements	0	$ 0
Short-term investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total investments	0		$ 142,677,000
Long-term investments [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total investments	$ 0		$ 33,212,000