Investment in Unconsolidated Subsidiary (Revenues and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 31, 2019
Expenses:
Operating income	$ 195,494	$ 48,237
Interest and debt expense, net	(315)	(324)
Diamond Green Diesel Holdings LLC Joint Venture [Member]
Revenues:
Operating revenues	358,615	302,718
Expenses:
Total costs and expenses less depreciation, amortization and accretion expense	151,347	243,063
Depreciation, amortization and accretion expense	11,774	11,418
Total costs and expenses	163,121	254,481
Other income	461	641
Net income	$ 195,640	$ 48,554