AOCI Related to Derivative Transactions (Detail) - USD ($) $ in Thousands		4 Months Ended
		Apr. 22, 2017	Apr. 23, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives	[1]	$ (3,518)	$ 2,588
Closed Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Estimated amount of derivatives to be reclassified in income from AOCI		(178)
Closed Contracts | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Estimated amount of derivatives to be reclassified in income from AOCI		(42)
Closed Contracts | Interest rate risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Estimated amount of derivatives to be reclassified in income from AOCI		(136)
Expiring in 2017
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives		(3,309)
Expiring in 2017 | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives		(3,309)
Expiring in 2018
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives		(661)
Expiring in 2018 | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives		(661)
Expiring in 2019
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives		43
Expiring in 2019 | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives		43
Closed or Expiring Over Next Three Years
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives		(4,105)
Closed or Expiring Over Next Three Years | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives		(3,969)
Closed or Expiring Over Next Three Years | Interest rate risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives		$ (136)

[1] Amounts in parentheses indicate debits to determine net income.