Pension Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 28, 2012	Jul. 30, 2011
Net periodic pension costs [Line Items]
Service cost	$ 308	$ 278
Interest cost	1,331	1,391
Expected return on plan assets	(1,714)	(1,705)
Net amortization	756	409
Net periodic pension cost	$ 681	$ 373