Correction of Consolidated Financial Statements (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 25, 2014	Apr. 26, 2013	Apr. 27, 2012
Property, plant and equipment	$ 1,607,231	$ 1,467,765
Accumulated depreciation	731,773	679,288
Deferred taxes	(14,173)	(20,731)
Tax benefit resulting from the cumulative effect of prior period errors	1,004	123	2,615
Worthless Stock Deduction
Taxes receivable	546
Basis differences on fixed assets
Taxes receivable	(1,688)
Deferred taxes	(8,038)
Property, Plant and Equipment
Property, plant and equipment	(14,413)
Accumulated Depreciation
Accumulated depreciation	(11,041)
Prior Period Errors
Tax benefit resulting from the cumulative effect of prior period errors		14,096
Construction in Progress | Land
Reclassification		6,562
Construction in Progress | Building and Improvements
Reclassification		28,741
Construction in Progress | Machinery and Equipment
Reclassification		$ 21,515