Business Segments (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 28, 2013 segment	Sep. 29, 2012	Sep. 28, 2013 segment	Sep. 29, 2012
Segment Reporting Information [Line Items]
Number of Business Segments	2		2
Net sales	$ 425,786	$ 452,732	$ 1,294,801	$ 1,276,514
Rendering [Member]
Segment Reporting Information [Line Items]
Net sales	362,077	368,154	1,079,848	1,061,947
Fat [Member] | Rendering [Member]
Segment Reporting Information [Line Items]
Net sales	195,400	205,900	580,900	626,000
Protein [Member] | Rendering [Member]
Segment Reporting Information [Line Items]
Net sales	$ 133,600	$ 137,100	$ 410,600	$ 361,900