Investment in Unconsolidated Subsidiary (Revenues and Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Expenses:
Operating income	$ 29,114	$ 10,861	$ 42,995	$ 10,545
Interest and debt expense, net	(1,928)	(3,352)	(4,742)	(7,508)
Diamond Green Diesel Holdings LLC Joint Venture [Member]
Revenues:
Operating revenues	132,226	156,160	203,994	272,888
Expenses:
Total costs and expenses less depreciation, amortization and accretion expense	95,565	140,343	148,074	252,378
Depreciation, amortization and accretion expense	7,547	4,956	12,925	9,965
Total costs and expenses	103,112	145,299	160,999	262,343
Other income	70	32	85	52
Net income	$ 27,256	$ 7,541	$ 38,338	$ 3,089