Derivative Financial Instruments - Fair Value of Interest Rate Contracts (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 26, 2014	Apr. 27, 2013
Derivatives, Fair Value [Line Items]
Interest rate contracts, assets, fair value	$ 1,716	$ 486
Interest rate contracts, liabilities, fair value	7,380	509
Other noncurrent assets [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Interest rate contracts, assets, fair value	1,716	486
Other noncurrent assets [Member] | Interest rate swap [Member]
Derivatives, Fair Value [Line Items]
Interest rate contracts, assets, fair value
Other noncurrent liabilities [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Interest rate contracts, liabilities, fair value	1,720	509
Other noncurrent liabilities [Member] | Interest rate swap [Member]
Derivatives, Fair Value [Line Items]
Interest rate contracts, liabilities, fair value	$ 5,660