Fair Value Measurements (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Assets and liabilities measured at fair value on a recurring basis
Cash equivalents		$ 25,496	$ 26,931	$ 1,491
Restricted cash		718	450	685
Commodity derivatives, net	[1]	27,419	11,789	29,582
Provisionally price contracts	[2]	131,192	(236,990)	115,122
Convertible preferred securities	[3]	775	13,550	13,300
Other assets and liabilities	[4]	9,290	5,661	8,066
Total		194,890	(178,609)	168,246
Level 1
Assets and liabilities measured at fair value on a recurring basis
Cash equivalents		25,496	26,931	1,491
Restricted cash		718	450	685
Commodity derivatives, net	[1]	38,070	26,890	60,796
Provisionally price contracts	[2]	88,356	(133,842)	55,141
Convertible preferred securities	[3]	0	0	0
Other assets and liabilities	[4]	13,958	8,635	11,583
Total		166,598	(70,936)	129,696
Level 2
Assets and liabilities measured at fair value on a recurring basis
Cash equivalents		0	0	0
Restricted cash		0	0	0
Commodity derivatives, net	[1]	(10,651)	(15,101)	(31,214)
Provisionally price contracts	[2]	42,836	(103,148)	59,981
Convertible preferred securities	[3]	0	0	0
Other assets and liabilities	[4]	(4,828)	(3,324)	(3,517)
Total		27,357	(121,573)	25,250
Level 3
Assets and liabilities measured at fair value on a recurring basis
Cash equivalents		0	0	0
Restricted cash		0	0	0
Commodity derivatives, net	[1]	0	0	0
Provisionally price contracts	[2]	0	0	0
Convertible preferred securities	[3]	775	13,550	13,300
Other assets and liabilities	[4]	160	350	0
Total		$ 935	$ 13,900	$ 13,300

[1] Includes associated cash posted/received as collateral

[2] Recorded in “Other noncurrent assets” on the Company’s Condensed Consolidated Balance Sheets

[3] Recorded in “Other noncurrent assets” on the Company’s Condensed Consolidated Balance Sheets

[4] Included in other assets and liabilities are deferred compensation assets, ethanol risk management contracts, and foreign exchange derivative contracts (Level 1), interest rate derivatives (Level 2), and contingent consideration to the former owners of Kay Flo Industries, Inc (Level 3).