Derivatives (Narrative) (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Sep. 26, 2020	Sep. 28, 2019	Dec. 28, 2019
Derivative [Line Items]
Net income	$ 101,605,000	$ 66,495,000	$ 86,091,000	$ 26,837,000	$ 31,044,000	$ 19,640,000	$ 254,191,000	$ 77,521,000
Commodity Contract [Member]
Derivative [Line Items]
Forward purchase amount	27,700,000						27,700,000
Cash Flow Hedging [Member]
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within 12 months							6,500,000
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	$ 200,000						$ 200,000		$ 400,000