Derivatives (Narrative) (Details) - USD ($)	3 Months Ended				6 Months Ended
	Jun. 27, 2020	Mar. 28, 2020	Jun. 29, 2019	Mar. 30, 2019	Jun. 27, 2020	Jun. 29, 2019	Dec. 28, 2019
Derivative [Line Items]
Net income	$ 66,495,000	$ 86,091,000	$ 31,044,000	$ 19,640,000	$ 152,586,000	$ 50,684,000
Commodity Contract [Member]
Derivative [Line Items]
Forward purchase amount	32,700,000				32,700,000
Cash Flow Hedging [Member]
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within 12 months					8,100,000
Net income					0
Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Asset Derivatives Fair Value	(100,000)				(100,000)		$ 1,300,000
Designated as Hedging Instrument [Member] | Other Current Assets [Member] | Corn Option [Member]
Derivative [Line Items]
Asset Derivatives Fair Value	$ 3,600,000				$ 3,600,000		$ 400,000