Segment Reporting (Details) - USD ($)		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Activities by segment [Abstract]
Revenues		$ 348,255,000	$ 439,893,000	$ 600,558,000	$ 555,573,000	$ 849,736,000	$ 1,173,970,000	$ 1,159,931,000	$ 949,189,000	$ 1,944,279,000	$ 4,132,826,000	$ 3,945,969,000
Segment Operating Earnings (loss)										7,580,000	18,094,000	43,436,000
Depreciation Depletion and Amortization										23,717,000	24,615,000	22,275,000
Inventory liquidation and valuation losses		5,357,000				14,247,000				5,357,000	14,247,000
Segment operating earnings [Abstract]
Segment operating earnings										7,580,000	18,094,000	43,436,000
General and administrative expenses										(9,939,000)	(8,613,000)	(9,060,000)
Operating (Loss) Earnings										(2,359,000)	9,481,000	34,376,000
Interest income										327,000	301,000	198,000
Interest expense										(13,000)	(2,000)	(24,000)
Earnings (loss) from continuing operations before income taxes										(2,045,000)	9,780,000	34,550,000
Identifiable Assets By Segment [Abstract]
Assets		243,215,000				340,814,000				243,215,000	340,814,000
Reportable Segments [Member]
Activities by segment [Abstract]
Revenues										1,944,279,000	4,132,826,000	3,945,969,000
Segment Operating Earnings (loss)										7,580,000	18,094,000	43,436,000
Depreciation Depletion and Amortization										23,717,000	24,615,000	22,275,000
Property and Equipment Additions										11,074,000	30,523,000	27,602,000
Segment operating earnings [Abstract]
Segment operating earnings										7,580,000	18,094,000	43,436,000
Identifiable Assets By Segment [Abstract]
Assets		243,215,000				340,814,000				243,215,000	340,814,000	448,082,000
Marketing [Member]
Activities by segment [Abstract]
Inventory liquidation and valuation losses		5,357,000				14,247,000				5,357,000	14,247,000	3,824,000
Marketing [Member] | Reportable Segments [Member]
Activities by segment [Abstract]
Revenues										1,875,885,000	4,050,497,000	3,863,057,000
Segment Operating Earnings (loss)	[1]									22,895,000	20,854,000	40,369,000
Depreciation Depletion and Amortization										11,097,000	9,626,000	7,682,000
Property and Equipment Additions										2,126,000	13,598,000	11,343,000
Segment operating earnings [Abstract]
Segment operating earnings	[1]									22,895,000	20,854,000	40,369,000
Identifiable Assets By Segment [Abstract]
Assets		96,723,000				189,332,000				96,723,000	189,332,000	306,693,000
Transportation [Member] | Reportable Segments [Member]
Activities by segment [Abstract]
Revenues										63,331,000	68,968,000	68,783,000
Segment Operating Earnings (loss)										3,701,000	4,750,000	5,180,000
Depreciation Depletion and Amortization										7,554,000	7,416,000	7,099,000
Property and Equipment Additions										6,579,000	8,994,000	3,165,000
Segment operating earnings [Abstract]
Segment operating earnings										3,701,000	4,750,000	5,180,000
Identifiable Assets By Segment [Abstract]
Assets		35,010,000				37,643,000				35,010,000	37,643,000	34,406,000
Oil and Gas [Member]
Activities by segment [Abstract]
Gain on property sale											2,528,000
Property impairments										12,082,000	8,009,000	2,630,000
Oil and Gas [Member] | Reportable Segments [Member]
Activities by segment [Abstract]
Revenues										5,063,000	13,361,000	14,129,000
Segment Operating Earnings (loss)	[2]									(19,016,000)	(7,510,000)	(2,113,000)
Depreciation Depletion and Amortization										5,066,000	7,573,000	7,494,000
Property and Equipment Additions										2,369,000	7,931,000	13,094,000
Segment operating earnings [Abstract]
Segment operating earnings	[2]									(19,016,000)	(7,510,000)	(2,113,000)
Identifiable Assets By Segment [Abstract]
Assets		8,930,000				25,888,000				8,930,000	25,888,000	37,093,000
Cash and other [Member] | Reportable Segments [Member]
Identifiable Assets By Segment [Abstract]
Assets		$ 102,552,000				$ 87,951,000				$ 102,552,000	$ 87,951,000	$ 69,890,000

[1] Marketing segment operating earnings included inventory liquidation and valuation losses totaling $5,357,000, $14,247,000 and $3,824,000 for 2015, 2014 and 2013, respectively.

[2] Oil and gas segment operating earnings include gains on property sales totaling $2,528,000 during 2014 and property impairments totaling $12,082,000, $8,009,000 and $2,630,000 for 2015, 2014 and 2013, respectively.