Fair Value of Financial Instruments - Schedule of Assets Measured at Fair Value (Detail) - USD ($) $ in Thousands	Jan. 28, 2017	Jan. 30, 2016
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	$ 8,003	$ 46,796
Total	183,892	199,651
Money market funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	2,510	70
Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	5,493	46,726
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	2,510	70
Total	5,063	29,910
Level 1 [Member] | Money market funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	2,510	70
Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	5,493	46,726
Total	178,829	169,741
Level 2 [Member] | Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total cash equivalents	5,493	46,726
Short-term investments [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	142,677	130,801
Short-term investments [Member] | Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	34,534	15,488
Short-term investments [Member] | Government agency obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	108,143	115,313
Short-term investments [Member] | Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	2,553	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	2,553	22,011
Short-term investments [Member] | Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	140,124	108,790
Short-term investments [Member] | Level 2 [Member] | Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	34,534	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	105,590	93,302
Long-term investments [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	33,212	22,054
Long-term investments [Member] | Government agency obligations [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total investments	33,212	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	33,212	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	$ 33,212	$ 14,225