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Income Taxes - Effective Income Tax Rate - Narrative (Detail) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Oct. 29, 2017
Oct. 30, 2016
Oct. 29, 2017
Oct. 30, 2016
Income Tax Disclosure [Abstract]        
Income taxes $ 2,108 $ 2,684 $ 3,748 $ 5,917
Effective income tax rate     29.10% 37.70%