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Employee Retirement Savings Plan and Deferred Compensation Plan (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Oct. 24, 2014
Oct. 18, 2015
Oct. 24, 2014
Defined Benefit Plan Disclosure [Line Items]      
Percent of employees' gross pay   6.00%  
Employer matching contribution (percent)   50.00%  
Defined contribution plan vesting period   5 years  
Pension expense $ 993 $ 1,029  
Base salary compensation eligible for deferral (percent)   50.00%  
Bonus or performance-based compensation eligible for deferral (percent)   100.00%  
Employee contributions matched (percent)   50.00%  
Maximum matched eligible earnings (percent)   6.00%  
Vesting period   5 years  
Company match expense $ 36 $ 57  
Foreign Pension Plan [Member] | Belgium [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Pension expense   216 $ 109
Matching pension expense   $ 75