Business Segments (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended												12 Months Ended			3 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2011 segment	Oct. 01, 2011	Jul. 02, 2011	Apr. 02, 2011	Jan. 01, 2011	Oct. 02, 2010	Jul. 03, 2010	Apr. 03, 2010	Dec. 31, 2011 segment		Jan. 01, 2011		Jan. 02, 2010		Jan. 01, 2011 Griffin and Nebraska Transactions [Member]	Jan. 02, 2010 Sanimax Transaction and Boca Transaction [Member]	Dec. 31, 2011 Geographic Concentration Risk [Member] country	Jan. 01, 2011 Geographic Concentration Risk [Member] country	Jan. 02, 2010 Geographic Concentration Risk [Member] country	Dec. 31, 2011 Geographic Concentration Risk [Member] Maximum [Member]	Dec. 31, 2011 Rendering [Member]	Jan. 01, 2011 Rendering [Member]	Jan. 02, 2010 Rendering [Member]	Jan. 02, 2010 Rendering [Member] Fat [Member]	Dec. 31, 2011 Rendering [Member] Fat [Member]	Jan. 01, 2011 Rendering [Member] Fat [Member]	Jan. 02, 2010 Rendering [Member] Protein [Member]	Dec. 31, 2011 Rendering [Member] Protein [Member]	Jan. 01, 2011 Rendering [Member] Protein [Member]
Segment Reporting Information [Line Items]
Number Of Foreign Countries Comprising More Than 5 Percent Of Entity's Consolidated Revenue																	0	0	0
Concentration Risk, Percentage																				5.00%
Number of Business Segments	2								2
Net sales	$ 430,866	$ 455,875	$ 470,610	$ 439,898	$ 227,232	$ 168,685	$ 166,210	$ 162,782	$ 1,797,249		$ 724,909		$ 597,806								$ 1,501,280	$ 714,685	$ 597,806	$ 283,700	$ 950,800	$ 399,100	$ 244,700	$ 447,700	$ 243,500
Capital expenditures									$ 60,153	[1]	$ 24,720	[1]	$ 23,638	[1]	$ 243,700	$ 8,000					$ 51,888	$ 21,431	$ 19,666

[1] Excludes the capital assets acquired as part of the acquisition of assets related to the Griffin Transaction and Nebraska Transaction in fiscal 2010 of approximately$243.7 million, the Sanimax Transaction and Boca Transaction in fiscal 2009 of approximately $8.0 million