Employee Benefits - Pension (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Jan. 26, 2019	Jan. 26, 2019
Net periodic pension costs
Service cost	$ 223	$ 869
Interest cost	1,116	3,348
Expected return on plan assets	(1,136)	(3,408)
Net amortization	639	1,917
Net periodic pension cost	$ 842	$ 2,726