Pension Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 25, 2015	Jul. 26, 2014
Components of net periodic pension cost
Service cost	$ 333	$ 279
Interest cost	1,211	1,267
Expected return on plan assets	(1,226)	(1,269)
Net amortization	736	665
Net periodic pension cost	$ 1,054	$ 942