Business Segments (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended											12 Months Ended
	Dec. 28, 2013 segment		Sep. 28, 2013		Jun. 29, 2013		Mar. 30, 2013	Dec. 29, 2012	Sep. 29, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 28, 2013 segment		Dec. 29, 2012		Dec. 31, 2011
Segment Reporting Information [Line Items]
Number of Business Segments	2											2
Net sales	$ 428,749	[1]	$ 425,786	[1]	$ 423,593	[1]	$ 445,422	$ 424,915	$ 452,732	$ 436,674	$ 387,108	$ 1,723,550		$ 1,701,429		$ 1,797,249
Capital expenditures												118,307	[2]	115,413	[2]	60,153	[2]
Terra Transaction and Rothsay Acquisition [Member]
Segment Reporting Information [Line Items]
Capital expenditures												167,000
BioPur Transaction [Member]
Segment Reporting Information [Line Items]
Capital expenditures														600
Rendering [Member]
Segment Reporting Information [Line Items]
Net sales												1,457,609		1,406,061		1,501,280
Capital expenditures												75,612		70,873		51,888
Rendering [Member] | Fat [Member]
Segment Reporting Information [Line Items]
Net sales												777,900		809,700		950,800
Rendering [Member] | Protein [Member]
Segment Reporting Information [Line Items]
Net sales												$ 552,900		$ 496,200		$ 447,700

[1] Included in net income are $0.8 million in transaction costs in the second quarter of fiscal 2013, $8.3 million in transaction costs in the third quarter of fiscal 2013 and $14.2 million in the fourth quarter relating to the Terra Transaction, Rothsay Acquisition and the VION Acquisition.

[2] Excludes the capital assets acquired as part of the acquisition of assets related to the Terra Transaction and the Rothsay Acquisition in fiscal 2013 of approximately $167.0 million and the BioPur acquisition in fiscal 2012 of approximately $0.6 million