Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 02, 2016	Jul. 04, 2015	Jul. 02, 2016	Jul. 04, 2015	Jan. 02, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 877,341	$ 859,315	$ 1,656,982	$ 1,734,009
Cost of sales and operating expenses	677,115	668,276	1,276,008	1,352,797
Selling, general and administrative expenses	76,158	84,294	157,627	170,925
Depreciation and amortization	69,531	66,245	141,787	132,643
Operating income	54,467	39,292	81,159	71,117
Equity in net income of unconsolidated subsidiaries	13,852	4,172	19,495	2,364
Total other expense	(26,345)	(33,862)	(54,154)	(59,940)
Income before income taxes	41,974	9,602	46,500	13,541
Segment Assets	4,859,894		4,859,894		$ 4,760,619
Feed Ingredients [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	542,955	529,429	1,019,126	1,076,927
Cost of sales and operating expenses	416,145	404,899	788,802	828,905
Gross Margin	126,810	124,530	230,324	248,022
Selling, general and administrative expenses	43,319	48,656	88,570	96,679
Acquisition and integration costs	0	0	0	0
Depreciation and amortization	42,119	40,485	86,496	80,539
Operating income	41,372	35,389	55,258	70,804
Equity in net income of unconsolidated subsidiaries	224	402	326	819
Segment income/(loss)	41,596	35,791	55,584	71,623
Segment Assets	2,507,473		2,507,473		2,438,869
Food Ingredients [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	272,120	283,354	520,017	553,511
Cost of sales and operating expenses	214,279	223,190	399,833	439,827
Gross Margin	57,841	60,164	120,184	113,684
Selling, general and administrative expenses	20,455	27,867	44,214	53,342
Acquisition and integration costs	0	0	0	0
Depreciation and amortization	17,736	16,785	34,440	33,982
Operating income	19,650	15,512	41,530	26,360
Equity in net income of unconsolidated subsidiaries	0	0	0	0
Segment income/(loss)	19,650	15,512	41,530	26,360
Segment Assets	1,477,927		1,477,927		1,448,014
Fuel Ingredients [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	62,266	46,532	117,839	103,571
Cost of sales and operating expenses	46,691	40,190	87,373	84,065
Gross Margin	15,575	6,342	30,466	19,506
Selling, general and administrative expenses	1,804	(2,295)	3,654	1,745
Acquisition and integration costs	0	0	0	0
Depreciation and amortization	7,184	6,599	14,103	13,230
Operating income	6,587	2,038	12,709	4,531
Equity in net income of unconsolidated subsidiaries	13,628	3,770	19,169	1,545
Segment income/(loss)	20,215	5,808	31,878	6,076
Segment Assets	638,764		638,764		631,968
Corporate [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	0	0	0	0
Cost of sales and operating expenses	0	(3)	0	0
Gross Margin	0	3	0	0
Selling, general and administrative expenses	10,580	10,066	21,189	19,159
Acquisition and integration costs	70	1,208	401	6,527
Depreciation and amortization	2,492	2,376	6,748	4,892
Operating income	(13,142)	(13,647)	(28,338)	(30,578)
Equity in net income of unconsolidated subsidiaries	0	0	0	0
Segment income/(loss)	(13,142)	(13,647)	(28,338)	(30,578)
Segment Assets	235,730		235,730		241,768
Operating Segments [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	877,341	859,315	1,656,982	1,734,009
Cost of sales and operating expenses	677,115	668,276	1,276,008	1,352,797
Gross Margin	200,226	191,039	380,974	381,212
Selling, general and administrative expenses	76,158	84,294	157,627	170,925
Acquisition and integration costs	70	1,208	401	6,527
Depreciation and amortization	69,531	66,245	141,787	132,643
Operating income	54,467	39,292	81,159	71,117
Equity in net income of unconsolidated subsidiaries	13,852	4,172	19,495	2,364
Segment income/(loss)	68,319	$ 43,464	100,654	$ 73,481
Segment Assets	$ 4,859,894		$ 4,859,894		$ 4,760,619