Comprehensive Income Reclassifications (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Jan. 02, 2021	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Jan. 02, 2021	Dec. 28, 2019	Dec. 29, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales		$ 1,019,839	$ 850,569	$ 848,673	$ 852,842	$ 859,428	$ 842,049	$ 827,324	$ 835,104	$ 3,571,923	$ 3,363,905	$ 3,387,726
Cost of sales and operating expenses										2,688,815	2,589,085	2,646,374
Amortization of prior service cost										(33)	(34)	(35)
Amortization of actuarial loss										(3,405)	(4,571)	(3,543)
Amortization of curtailment										(69)		(498)
Amortization of settlement										30	(66)	3
Income taxes										(53,289)	(59,467)	(12,031)
Net income		$ 44,745	$ 101,125	$ 65,439	$ 85,510	$ 242,609	$ 25,721	$ 26,258	$ 18,012	296,819	312,600	101,496
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income										5,967	(4,722)	(1,741)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] | Soybean Meal [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales										(49)	0	8
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] | Foreign Exchange Contract [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales										13,809	(1,345)	0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivative Instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income from operations before income taxes										13,637	(1,767)	1,906
Income taxes										(5,071)	548	(492)
Net income										8,566	(1,219)	1,414
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivative Instruments | Natural Gas Swap [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales and operating expenses										0	0	(14)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivative Instruments | Corn Option [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales and operating expenses										(123)	(422)	1,912
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined Benefit Pension Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of prior service cost	[1]									(33)	(34)	(35)
Amortization of actuarial loss	[1]									(3,405)	(4,571)	(3,543)
Amortization of curtailment	[1]									(69)	0	(498)
Amortization of settlement	[1]									30	(66)	3
Income from operations before income taxes										(3,477)	(4,671)	(4,073)
Income taxes										878	1,168	918
Net income										$ (2,599)	$ (3,503)	$ (3,155)

[1] These items are included in the computation of net periodic pension cost. See Note 15 Employee Benefit Plans for additional information.