Business Segments (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 29, 2013 segment	Jun. 30, 2012	Jun. 29, 2013 segment	Jun. 30, 2012
Segment Reporting Information [Line Items]
Number of Business Segments	2		2
Net sales	$ 423,593	$ 436,674	$ 869,015	$ 823,782
Rendering [Member]
Segment Reporting Information [Line Items]
Net sales	350,597	371,481	717,771	693,793
Fat [Member] | Rendering [Member]
Segment Reporting Information [Line Items]
Net sales	186,300	226,100	385,500	420,100
Protein [Member] | Rendering [Member]
Segment Reporting Information [Line Items]
Net sales	$ 138,100	$ 121,300	$ 277,000	$ 224,800