Fair Value of Financial Instruments - Schedule of Assets Measured at Fair Value (Detail) - USD ($) $ in Thousands	Apr. 30, 2016	Jan. 30, 2016
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	$ 17,239	$ 46,796
Total	128,193	199,651
Money market funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	250	70
Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	16,989	46,726
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	250	70
Total	30,094	29,910
Level 1 [Member] | Money market funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	250	70
Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	16,989	46,726
Total	98,099	169,741
Level 2 [Member] | Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	16,989	46,726
Short-term investments [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	100,095	130,801
Short-term investments [Member] | Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	17,668	15,488
Short-term investments [Member] | Government agency obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	82,427	115,313
Short-term investments [Member] | Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	29,844	22,011
Short-term investments [Member] | Level 1 [Member] | Government agency obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	29,844	22,011
Short-term investments [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	70,251	108,790
Short-term investments [Member] | Level 2 [Member] | Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	17,668	15,488
Short-term investments [Member] | Level 2 [Member] | Government agency obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	52,583	93,302
Long-term investments [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	10,859	22,054
Long-term investments [Member] | Government agency obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	10,859	22,054
Long-term investments [Member] | Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments		7,829
Long-term investments [Member] | Level 1 [Member] | Government agency obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments		7,829
Long-term investments [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	10,859	14,225
Long-term investments [Member] | Level 2 [Member] | Government agency obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	$ 10,859	$ 14,225