Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 02, 2011	Jul. 03, 2010	Jul. 02, 2011	Jul. 03, 2010
Segment Reporting Information [Line Items]
Number of Business Segments	2		2
Net sales	$ 470,610	$ 166,210	$ 910,508	$ 328,992
Rendering [Member]
Segment Reporting Information [Line Items]
Net sales	392,675	166,210	764,245	328,992
Fat [Member]
Segment Reporting Information [Line Items]
Net sales	245,500	92,600	481,700	175,700
Protein [Member]
Segment Reporting Information [Line Items]
Net sales	$ 120,400	$ 55,400	$ 230,500	$ 116,800