Fair Value of Financial Instruments - Narrative (Detail) - USD ($)	Jul. 31, 2016	May 01, 2016		Aug. 02, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term investments	$ 2,434,000	$ 4,359,000	[1]	$ 6,336,000
Long-term investments	4,611,000	4,025,000	[1]	2,893,000
Short-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized gain (loss) on investments	(33,000)	(100,000)		$ (184,000)
Long-term Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unrealized gain (loss) on investments	$ (15,000)	$ (44,000)

[1] Derived from audited financial statements.