Investment in Unconsolidated Subsidiary (Revenues and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended								9 Months Ended
	Sep. 30, 2020	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Sep. 30, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Sep. 30, 2020	Sep. 26, 2020	Sep. 30, 2019	Sep. 28, 2019
Revenues:
Operating revenues		$ 850,569				$ 842,049				$ 2,552,084		$ 2,504,477
Expenses:
Cost of sales and operating expenses		638,368				652,923				1,917,623		1,948,552
Total costs and expenses		814,213				814,210				2,447,923		2,416,333
Operating income		127,455				59,859				356,572		182,534
Net income		$ 101,605	$ 66,495	$ 86,091		$ 26,837	$ 31,044	$ 19,640		$ 254,191		$ 77,521
Diamond Green Diesel Holdings LLC Joint Venture [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Revenues:
Operating revenues					$ 262,118						$ 859,647
Expenses:
Cost of sales and operating expenses					183,022						633,109
Depreciation, amortization and accretion expense					15,242						38,574
Total costs and expenses					198,264						671,683
Operating income					63,854						187,964
Other income					506						1,781
Interest and debt expense, net					(320)						(965)
Net income					$ 64,040						$ 188,780
Diamond Green Diesel Holdings LLC Joint Venture [Member] | Equity Method Investment, Nonconsolidated Investee or Group of Investees | Subsequent Event
Revenues:
Operating revenues	$ 346,276								$ 1,000,717
Expenses:
Cost of sales and operating expenses	153,406								462,364
Depreciation, amortization and accretion expense	10,772								33,660
Total costs and expenses	164,178								496,024
Operating income	182,098								504,693
Other income	415								1,076
Interest and debt expense, net	(315)								(947)
Net income	$ 182,198								$ 504,822