Investment in Unconsolidated Subsidiary (Revenues and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 03, 2021	Mar. 31, 2021	Mar. 31, 2020	Mar. 28, 2020
Revenues:
Operating revenues	$ 1,046,716			$ 852,842
Expenses:
Cost of sales and operating expenses	772,784			646,908
Total costs and expenses	949,430			827,833
Operating income	199,511			122,829
Net income	$ 153,418			$ 86,091
Diamond Green Diesel Holdings LLC Joint Venture [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Revenues:
Operating revenues		$ 431,633	$ 358,615
Expenses:
Cost of sales and operating expenses		215,234	151,347
Depreciation, amortization and accretion expense		11,687	11,774
Total costs and expenses		226,921	163,121
Operating income		204,712	195,494
Other income		58	461
Interest and debt expense, net		(320)	(315)
Net income		$ 204,450	$ 195,640