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Financial Instruments and Fair Value Measurements - Additional Information (Detail) - USD ($)
12 Months Ended
Apr. 27, 2018
Apr. 28, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other-than-temporary impairment recognized on investments $ 0  
Significant Other Observable Inputs (Level 2)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt Instrument, Fair Value Disclosure $ 1,523,000,000 $ 1,520,000,000