Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019	Dec. 28, 2019
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 850,569	$ 842,049	$ 2,552,084	$ 2,504,477
Cost of sales and operating expenses	638,368	652,923	1,917,623	1,948,552
Gain (Loss) on Disposition of Assets	(122)	2,669	(210)	20,845
Selling, general and administrative expenses	89,993	83,549	276,379	249,569
Depreciation and amortization	85,730	80,407	253,711	239,057
Equity in net income of Diamond Green Diesel	91,099	32,020	252,411	94,390
Operating income	127,455	59,859	356,572	182,534
Equity in net income/(loss) of other unconsolidated subsidiaries	906	(665)	2,467	(1,087)
Total other expense	(21,944)	(21,507)	(61,790)	(80,026)
Income before income taxes	106,417	37,687	297,249	101,421
Segment Assets	5,380,986		5,380,986		$ 5,345,258
Feed Ingredients
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	483,025	496,978	1,499,340	1,480,244
Cost of sales and operating expenses	361,576	379,792	1,117,931	1,143,606
Gross Margin	121,449	117,186	381,409	336,638
Gain (Loss) on Disposition of Assets	167	(2,429)	293	(7,343)
Selling, general and administrative expenses	49,028	47,319	153,459	142,615
Depreciation and amortization	53,764	50,182	159,968	148,271
Equity in net income of Diamond Green Diesel	0	0	0	0
Operating income	18,490	22,114	67,689	53,095
Equity in net income/(loss) of other unconsolidated subsidiaries	906	(665)	2,467	(1,087)
Segment income/(loss)	19,396	21,449	70,156	52,008
Segment Assets	2,604,359		2,604,359		2,653,363
Food Ingredients
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	291,842	276,467	841,070	830,466
Cost of sales and operating expenses	226,745	214,643	652,334	643,091
Gross Margin	65,097	61,824	188,736	187,375
Gain (Loss) on Disposition of Assets	16	(253)	(30)	(13,518)
Selling, general and administrative expenses	23,366	22,811	71,406	68,129
Depreciation and amortization	20,648	19,743	60,925	59,115
Equity in net income of Diamond Green Diesel	0	0	0	0
Operating income	21,067	19,523	56,435	73,649
Equity in net income/(loss) of other unconsolidated subsidiaries	0	0	0	0
Segment income/(loss)	21,067	19,523	56,435	73,649
Segment Assets	1,300,097		1,300,097		1,345,526
Fuel Ingredients
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	75,702	68,604	211,674	193,767
Cost of sales and operating expenses	50,047	58,488	147,358	161,855
Gross Margin	25,655	10,116	64,316	31,912
Gain (Loss) on Disposition of Assets	(61)	13	(53)	16
Selling, general and administrative expenses	5,038	912	10,645	583
Depreciation and amortization	8,633	7,895	24,705	24,055
Equity in net income of Diamond Green Diesel	91,099	32,020	252,411	94,390
Operating income	103,144	33,316	281,430	101,648
Equity in net income/(loss) of other unconsolidated subsidiaries	0	0	0	0
Segment income/(loss)	103,144	33,316	281,430	101,648
Segment Assets	1,117,186		1,117,186		1,087,701
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	0	0	0	0
Cost of sales and operating expenses	0	0	0	0
Gross Margin	0	0	0	0
Gain (Loss) on Disposition of Assets	0	0	0	0
Selling, general and administrative expenses	12,561	12,507	40,869	38,242
Depreciation and amortization	2,685	2,587	8,113	7,616
Equity in net income of Diamond Green Diesel	0	0	0	0
Operating income	(15,246)	(15,094)	(48,982)	(45,858)
Equity in net income/(loss) of other unconsolidated subsidiaries	0	0	0	0
Segment income/(loss)	(15,246)	(15,094)	(48,982)	(45,858)
Segment Assets	359,344		359,344		258,668
Total
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	850,569	842,049	2,552,084	2,504,477
Cost of sales and operating expenses	638,368	652,923	1,917,623	1,948,552
Gross Margin	212,201	189,126	634,461	555,925
Gain (Loss) on Disposition of Assets	122	(2,669)	210	(20,845)
Selling, general and administrative expenses	89,993	83,549	276,379	249,569
Depreciation and amortization	85,730	80,407	253,711	239,057
Equity in net income of Diamond Green Diesel	91,099	32,020	252,411	94,390
Operating income	127,455	59,859	356,572	182,534
Equity in net income/(loss) of other unconsolidated subsidiaries	906	(665)	2,467	(1,087)
Segment income/(loss)	128,361	$ 59,194	359,039	$ 181,447
Segment Assets	$ 5,380,986		$ 5,380,986		$ 5,345,258