AOCI Related to Derivative Transactions (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 15, 2017	Jul. 16, 2016	Jul. 15, 2017	Jul. 16, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives	[1]	$ 7,238	$ (3,525)	$ 3,720	$ (937)
Closed Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Estimated amount of derivatives to be reclassified in income from AOCI				(410)
Closed Contracts | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Estimated amount of derivatives to be reclassified in income from AOCI				(295)
Closed Contracts | Interest rate risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Estimated amount of derivatives to be reclassified in income from AOCI				(115)
Expiring in 2017
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives				1,650
Expiring in 2017 | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives				1,650
Expiring in 2018
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives				2,257
Expiring in 2018 | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives				2,257
Expiring in 2019
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives				(44)
Expiring in 2019 | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives				(44)
Closed or Expiring Over Next Three Years
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives				3,453
Closed or Expiring Over Next Three Years | Commodity price risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives				3,568
Closed or Expiring Over Next Three Years | Interest rate risk derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net change in fair value of derivatives				$ (115)

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