Comprehensive Income Reclassifications (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales and operating expenses										$ 2,875,851	$ 2,635,547	$ 2,654,025
Amortization of prior service cost										(35)	(36)	67
Amortization of actuarial loss										4,786	4,632	5,101
Amortization of curtailment												(1,181)
Amortization of settlement										42	(114)	5,291
Income taxes										69,154	(15,315)	(13,501)
Net income		$ 105,729	$ 7,761	$ 9,149	$ 5,829	$ 40,541	$ 28,694	$ 31,999	$ 1,079	128,468	102,313	78,531
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income										159	(434)	(5,126)
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										5,220	3,868	1,517
Income taxes										(2,025)	(1,501)	(589)
Net income										3,195	2,367	928
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										(35)	0	0
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										5,255	3,868	1,517
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]									(35)	(36)	67
Amortization of actuarial loss	[1]									(4,786)	(4,632)	(5,101)
Amortization of curtailment	[1]									0	0	1,181
Amortization of settlement	[1]									(42)	114	(5,291)
Income from operations before income taxes										(4,863)	(4,554)	(9,144)
Income taxes										1,827	1,753	3,090
Net income										$ (3,036)	$ (2,801)	$ (6,054)

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