Employees Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 27, 2018	Oct. 28, 2017	Oct. 27, 2018	Oct. 28, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions, employee benefit expenses	$ 1,384	$ 1,766	$ 3,469	$ 3,765