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Fair Value of Financial Instruments - Narrative (Detail) - USD ($)
3 Months Ended
Aug. 04, 2019
Apr. 28, 2019
Jul. 29, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Long-term investments (Rabbi Trust) $ 7,347,000 $ 7,081,000 [1] $ 7,671,000
U.S. Corporate Bonds [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Held to maturity investments   5,000,000 30,800,000
Held to maturity investments, fair value   5,000,000 30,600,000
U.S. Corporate Bonds [Member] | Minimum [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Long-term investments, maturity period 2 years    
U.S. Corporate Bonds [Member] | Maximum [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Long-term investments, maturity period 2 years 6 months    
Long-term investments (Rabbi Trust) [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Accumulated unrealized gain (loss) on investments $ 46,000 $ 40,000 $ 104,000
[1] Derived from audited financial statements.