Effect of Derivative Instruments for Deferred Gains And (Losses) on Closed Contracts and Effective Portion in Fair Value on AOCI, Utilized for Risk Management Purposes (Detail) - USD ($) $ in Thousands		3 Months Ended												4 Months Ended				12 Months Ended
		Dec. 28, 2019	[1]	Oct. 05, 2019	[1]	Jul. 13, 2019	[1]	Dec. 29, 2018	[1]	Oct. 06, 2018	[1]	Jul. 14, 2018	[1]	Apr. 20, 2019	[1]	Apr. 21, 2018	[1]	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion) (Net of tax)																		$ 8,457	$ 2,978	$ (6,789)
Production costs		$ 485,960		$ 509,056		$ 508,552		$ 467,155		$ 485,680		$ 488,871		$ 652,141		$ 625,122		2,155,709	2,066,828	2,009,473
Income before income taxes																		212,083	197,161	149,293
Reclassification out of Accumulated Other Comprehensive Income
Derivative Instruments, Gain (Loss) [Line Items]
Income before income taxes																		2,664	(1,079)	(1,367)
Commodity Contract
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion) (Net of tax)																		8,457	2,978	(6,789)
Commodity Contract | Product | Reclassification out of Accumulated Other Comprehensive Income
Derivative Instruments, Gain (Loss) [Line Items]
Production costs	[2]																	2,771	(972)	(1,279)
Interest Rate Contracts | Reclassification out of Accumulated Other Comprehensive Income
Derivative Instruments, Gain (Loss) [Line Items]
Interest (expense) income																		$ (107)	$ (107)	$ (88)

[1] The company does not report gross margin.  This line item presents our material, supplies, labor and other production costs (exclusive of depreciation and amortization shown separately) under an alternative presentation.

[2] Included in Materials, supplies, labor and other production costs (exclusive of depreciation and amortization shown separately).