General (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Oct. 01, 2011	Jul. 02, 2011	Apr. 02, 2011	Jan. 01, 2011	Oct. 02, 2010	Jul. 03, 2010	Apr. 03, 2010	Dec. 31, 2011	Jan. 01, 2011	Jan. 02, 2010	Dec. 31, 2011 Stock Options [Member]	Jan. 01, 2011 Stock Options [Member]	Jan. 02, 2010 Stock Options [Member]	Dec. 31, 2011 Non Vested Stock [Member]	Jan. 01, 2011 Non Vested Stock [Member]	Jan. 02, 2010 Non Vested Stock [Member]	Dec. 31, 2011 Griffin Transaction [Member] weeks	Jan. 01, 2011 Griffin Transaction [Member] weeks	Dec. 31, 2011 Buildings and improvements [Member] year	Dec. 31, 2011 Machinery and equipment [Member] year	Dec. 31, 2011 Vehicles [Member] year	Dec. 31, 2011 Aircraft [Member] year	Dec. 31, 2011 Routes [Member] year	Dec. 31, 2011 Permits [Member] year	Dec. 31, 2011 Non-compete agreements [Member] year	Dec. 31, 2011 Trade Names [Member] year	Dec. 31, 2011 Darling International Senior Unsecured Restricted Notes [Member] Unsecured Debt [Member]	Jan. 01, 2011 Darling International Senior Unsecured Restricted Notes [Member] Unsecured Debt [Member]	Dec. 31, 2011 Credit Agreement Term Loan [Member] Secured Debt [Member]	Jan. 01, 2011 Credit Agreement Term Loan [Member] Secured Debt [Member]	Dec. 17, 2010 Credit Agreement Term Loan [Member] Secured Debt [Member]	Dec. 31, 2011 Minimum [Member] facilities
General [Line Items]
Number of Processing and Transfer Facilities																																	120
Number Of Weeks Of Contribution In Year End Results From Assets Acquired																		52	2
Accounting Policies [Abstract]
Minimum Weeks In Fiscal Year									52
Maximum Weeks In Fiscal Year									53
Number Of Weeks Year To Date									52	52	52
Cash and Cash Equivalents [Abstract]
Investments Classified As Cash Equivalents, Original Maturity									3 months
Long Lived Assets [Abstract]
Property, Plant and Equipment, Useful Life, Minimum																				15	3	2
Property, Plant and Equipment, Useful Life, Maximum																				30	10	6
Property, Plant and Equipment, Useful Life, Average																							7
Finite-Lived Intangible Assets, Useful Life, Minimum																								5	11	3
Finite-Lived Intangible Assets, Useful Life, Maximum																								20	20	7
Finite-Lived Intangible Assets, Useful Life																											15
Goodwill [Abstract]
Goodwill	$ 381,369,000				$ 376,263,000				$ 381,369,000	$ 376,263,000
Basic:
Net income									169,418,000	44,243,000	41,790,000
Shares									114,924,000	82,854,000	82,142,000
Basic earnings per share	$ 0.25	$ 0.35	$ 0.45	$ 0.43	$ 0.12	$ 0.14	$ 0.14	$ 0.14	$ 1.47	$ 0.53	$ 0.51
Effect of dilutive securities: [Abstract]
Add: Option shares in the money and dilutive effect of non-vested stock									972,000	778,000	778,000
Less: Pro forma treasury shares									(371,000)	(389,000)	(445,000)
Diluted:
Net Income									169,418,000	44,243,000	41,790,000
Shares									115,525,000	83,243,000	82,475,000
Per Share	$ 0.25	$ 0.35	$ 0.44	$ 0.43	$ 0.12	$ 0.14	$ 0.14	$ 0.14	$ 1.47	$ 0.53	$ 0.51
Antidilutive Securities [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount												63,272	87,843	32,000	330,268	75,714	0
Stock Based Compensation [Abstract]
Stock-based compensation expense									4,900,000	2,800,000	1,200,000
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense									1,900,000	1,100,000	500,000
Excess tax benefits from stock-based compensation									1,125,000	234,000	(39,000)
Financial Instruments [Abstract]
Long-term Debt	280,030,000				710,039,000				280,030,000	710,039,000																		250,000,000	250,000,000	30,000,000	300,000,000	300,000,000
Long-term Debt, Fair Value																												$ 277,500,000	$ 260,600,000	$ 30,900,000