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Financial Instruments and Fair Value Measurements - Additional Information (Detail) - USD ($)
$ in Millions
Oct. 27, 2017
Apr. 28, 2017
Significant Other Observable Inputs (Level 2)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Debt Instrument, Fair Value Disclosure $ 2,316 $ 1,520