Investment in Unconsolidated Subsidiary (Assets, Liabilities and members' equity) (Details) - USD ($) $ in Thousands	Mar. 30, 2019	Dec. 31, 2018
ASSETS
Property, plant and equipment, net	$ 591,927	$ 576,384
Diamond Green Diesel Holdings LLC Joint Venture [Member]
ASSETS
Total current assets	225,948	186,258
Other assets	26,427	24,601
Total assets	844,302	787,243
Liabilities and members' equity:
Total current portion of long term debt	276	189
Total other current liabilities	44,440	40,619
Total long term debt	9,010	8,485
Total other long term liabilities	4,612	539
Total liabilities and members' equity	785,964	737,411
Equity Method Investment, Summarized Financial Information, Liabilities and Equity	$ 844,302	$ 787,243