Comprehensive Income Reclassifications (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net sales		$ 859,428	$ 842,049	$ 827,324	$ 835,104	$ 853,130	$ 812,576	$ 846,646	$ 875,374	$ 3,363,905	$ 3,387,726	$ 3,662,251
Cost of sales and operating expenses										2,589,085	2,646,374	2,875,680
Amortization of prior service cost										(34)	(35)	(35)
Amortization of actuarial loss										4,571	3,543	4,786
Amortization of curtailment											498
Amortization of settlement										66	(3)	42
Income taxes										(59,467)	(12,031)	69,154
Net income		$ 242,609	$ 25,721	$ 26,258	$ 18,012	$ 40,648	$ (6,037)	$ (30,420)	$ 97,305	312,600	101,496	128,468
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income										(4,722)	(1,741)	159
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										0	8	0
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										(1,345)	0	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										(1,767)	1,906	5,220
Income taxes										548	(492)	(2,025)
Net income										(1,219)	1,414	3,195
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	(14)	(35)
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										(422)	1,912	5,255
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]									(34)	(35)	(35)
Amortization of actuarial loss	[1]									(4,571)	(3,543)	(4,786)
Amortization of curtailment	[1]									0	(498)	0
Amortization of settlement	[1]									(66)	3	(42)
Income from operations before income taxes										(4,671)	(4,073)	(4,863)
Income taxes										1,168	918	1,827
Net income										$ (3,503)	$ (3,155)	$ (3,036)

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