Segment Reporting (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Activities by segment [Abstract]
Revenues	$ 849,736,000	$ 1,173,970,000	$ 1,159,931,000	$ 949,189,000	$ 968,096,000	$ 1,060,340,000	$ 965,098,000	$ 952,435,000	$ 4,132,826,000		$ 3,945,969,000		$ 3,376,085,000
Segment Operating Earnings (loss)									18,094,000		43,436,000		52,766,000
Depreciation Depletion and Amortization									24,615,000		22,275,000		20,714,000
Inventory liquidation and valuation losses	14,247,000				3,824,000				14,247,000		3,824,000
Segment operating earnings [Abstract]
Segment operating earnings									18,094,000		43,436,000		52,766,000
General and administrative expenses									(8,613,000)		(9,060,000)		(8,810,000)
Operating Earnings									9,481,000		34,376,000		43,956,000
Interest income									301,000		198,000		190,000
Interest expense									(2,000)		(24,000)		(10,000)
Earnings from continuing operations before income taxes									9,780,000		34,550,000		44,136,000
Identifiable Assets By Segment [Abstract]
Assets	340,814,000				448,082,000				340,814,000		448,082,000
Reportable Segments [Member]
Activities by segment [Abstract]
Revenues									4,132,826,000		3,945,969,000		3,376,085,000
Segment Operating Earnings (loss)									18,094,000		43,436,000		52,766,000
Depreciation Depletion and Amortization									24,615,000		22,275,000		20,714,000
Property and Equipment Additions									30,523,000		27,602,000		51,012,000
Segment operating earnings [Abstract]
Segment operating earnings									18,094,000		43,436,000		52,766,000
Identifiable Assets By Segment [Abstract]
Assets	340,814,000				448,082,000				340,814,000		448,082,000		419,501,000
Marketing [Member]
Activities by segment [Abstract]
Inventory liquidation and valuation losses	14,247,000				3,824,000				14,247,000		3,824,000		1,596,000
Marketing [Member] | Reportable Segments [Member]
Activities by segment [Abstract]
Revenues									4,050,497,000		3,863,057,000		3,292,948,000
Segment Operating Earnings (loss)									20,854,000	[1]	40,369,000	[1]	46,145,000	[1]
Depreciation Depletion and Amortization									9,626,000		7,682,000		5,945,000
Property and Equipment Additions									13,598,000		11,343,000		12,391,000
Segment operating earnings [Abstract]
Segment operating earnings									20,854,000	[1]	40,369,000	[1]	46,145,000	[1]
Identifiable Assets By Segment [Abstract]
Assets	189,332,000				306,693,000				189,332,000		306,693,000		277,920,000
Transportation [Member] | Reportable Segments [Member]
Activities by segment [Abstract]
Revenues									68,968,000		68,783,000		67,183,000
Segment Operating Earnings (loss)									4,750,000		5,180,000		10,253,000
Depreciation Depletion and Amortization									7,416,000		7,099,000		5,921,000
Property and Equipment Additions									8,994,000		3,165,000		15,538,000
Segment operating earnings [Abstract]
Segment operating earnings									4,750,000		5,180,000		10,253,000
Identifiable Assets By Segment [Abstract]
Assets	37,643,000				34,406,000				37,643,000		34,406,000		38,940,000
Oil and Gas [Member]
Activities by segment [Abstract]
Gain on property sale									2,528,000				2,203,000
Property impairments									8,009,000		2,630,000		5,555,000
Oil and Gas [Member] | Reportable Segments [Member]
Activities by segment [Abstract]
Revenues									13,361,000		14,129,000		15,954,000
Segment Operating Earnings (loss)									(7,510,000)	[2]	(2,113,000)	[2]	(3,632,000)	[2]
Depreciation Depletion and Amortization									7,573,000		7,494,000		8,848,000
Property and Equipment Additions									7,931,000		13,094,000		23,083,000
Segment operating earnings [Abstract]
Segment operating earnings									(7,510,000)	[2]	(2,113,000)	[2]	(3,632,000)	[2]
Identifiable Assets By Segment [Abstract]
Assets	25,888,000				37,093,000				25,888,000		37,093,000		35,788,000
Cash and other [Member] | Reportable Segments [Member]
Identifiable Assets By Segment [Abstract]
Assets	$ 87,951,000				$ 69,890,000				$ 87,951,000		$ 69,890,000		$ 66,853,000

[1] Marketing segment operating earnings included inventory liquidation and valuation losses totaling $14,247,000, $3,824,000 and $1,596,000 for 2014, 2013 and 2012, respectively.

[2] Oil and gas segment operating earnings include gains on property sales totaling $2,528,000 and $2,203,000 during 2014 and 2012, respectively, and property impairments totaling $8,009,000, $2,630,000 and $5,555,000 for 2014, 2013 and 2012, respectively.