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Accounts Receivable - Allowance for Doubtful Accounts (Detail) - Allowance for doubtful accounts [Member] - USD ($)
$ in Thousands
9 Months Ended
Jan. 28, 2018
Jan. 29, 2017
Valuation and Qualifying Accounts Disclosure [Line Items]    
Beginning balance $ (414) $ (1,088)
Provision for bad debts 57 239
Net write-offs, net of recoveries   452
Ending balance $ (357) $ (397)