Accumulated Other Comprehensive Loss (Income) Related to Derivative Transactions (Detail) (USD $)	4 Months Ended
	Apr. 25, 2015	Apr. 19, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss) related to commodity price risk and interest rate risk derivative transactions	$ (4,428,000)	$ 15,302,000
Closed or Expiring Over Next Three Years
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss) related to commodity price risk and interest rate risk derivative transactions	14,300,000
Closed or Expiring Over Next Three Years | Closed Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Estimated amount of derivatives to be reclassified in income from AOCI	1,400,000
Closed or Expiring Over Next Three Years | Expiring in 2015
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss) related to commodity price risk and interest rate risk derivative transactions	10,200,000
Closed or Expiring Over Next Three Years | Expiring in 2016 and beyond
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss) related to commodity price risk and interest rate risk derivative transactions	2,700,000
Commodity price risk derivatives | Closed or Expiring Over Next Three Years
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss) related to commodity price risk and interest rate risk derivative transactions	13,200,000
Commodity price risk derivatives | Closed or Expiring Over Next Three Years | Closed Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Estimated amount of derivatives to be reclassified in income from AOCI	300,000
Commodity price risk derivatives | Closed or Expiring Over Next Three Years | Expiring in 2015
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss) related to commodity price risk and interest rate risk derivative transactions	10,200,000
Commodity price risk derivatives | Closed or Expiring Over Next Three Years | Expiring in 2016 and beyond
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss) related to commodity price risk and interest rate risk derivative transactions	2,700,000
Interest rate risk derivatives | Closed or Expiring Over Next Three Years
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss) related to commodity price risk and interest rate risk derivative transactions	1,100,000
Interest rate risk derivatives | Closed or Expiring Over Next Three Years | Closed Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Estimated amount of derivatives to be reclassified in income from AOCI	$ 1,100,000