Investment in Unconsolidated Subsidiary (Revenues and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Expenses:
Operating income	$ 14,406	$ 37,642	$ 33,158	$ 80,637
Interest and debt expense, net	(455)	(1,406)	(2,306)	(6,148)
Diamond Green Diesel Holdings LLC Joint Venture [Member]
Revenues:
Operating revenues	175,585	141,656	451,768	345,650
Expenses:
Total costs and expenses less depreciation, amortization and accretion expense	154,446	96,569	395,743	244,643
Depreciation, amortization and accretion expense	6,733	7,445	22,867	20,370
Total costs and expenses	161,179	104,014	418,610	265,013
Other income	408	114	959	199
Net income	$ 14,359	$ 36,350	$ 31,811	$ 74,688