Segment Reporting (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012		Dec. 31, 2011
Activities by segment [Abstract]
Revenues	$ 968,096,000	$ 1,060,340,000	$ 965,098,000	$ 952,435,000	$ 875,666,000	$ 794,404,000	$ 830,110,000	$ 875,905,000	$ 3,945,969,000	$ 3,376,085,000		$ 3,038,737,000
Segment Operating Earnings (loss)									43,436,000	52,766,000		43,884,000
Depreciation Depletion and Amortization									22,275,000	20,714,000		15,885,000
Property and Equipment Additions									27,602,000	51,012,000		52,252,000
Gain on property sale									683,000	6,298,000		4,394,000
Segment operating earnings [Abstract]
Segment operating earnings									43,436,000	52,766,000		43,884,000
General and administrative expenses									(9,060,000)	(8,810,000)		(8,678,000)
Operating Earnings									34,376,000	43,956,000		35,206,000
Interest income									198,000	190,000		237,000
Interest expense									(24,000)	(10,000)		(8,000)
Earnings from continuing operations before income taxes									34,550,000	44,136,000		35,435,000
Identifiable assets by segment [Abstract]
Assets	448,082,000				419,501,000				448,082,000	419,501,000		378,840,000
Marketing [Member]
Activities by segment [Abstract]
Revenues									3,863,057,000	3,292,948,000		2,961,176,000
Segment Operating Earnings (loss)									40,369,000	46,145,000		49,237,000
Depreciation Depletion and Amortization									7,682,000	5,945,000		3,724,000
Property and Equipment Additions									11,343,000	12,391,000		13,554,000
Segment operating earnings [Abstract]
Segment operating earnings									40,369,000	46,145,000		49,237,000
Identifiable assets by segment [Abstract]
Assets	306,693,000				277,920,000				306,693,000	277,920,000		253,817,000
Transportation [Member]
Activities by segment [Abstract]
Revenues									68,783,000	67,183,000		63,501,000
Segment Operating Earnings (loss)									5,180,000	10,253,000		8,521,000
Depreciation Depletion and Amortization									7,099,000	5,921,000		3,912,000
Property and Equipment Additions									3,165,000	15,538,000		14,118,000
Segment operating earnings [Abstract]
Segment operating earnings									5,180,000	10,253,000		8,521,000
Identifiable assets by segment [Abstract]
Assets	34,406,000				38,940,000				34,406,000	38,940,000		27,221,000
Oil and Gas [Member]
Activities by segment [Abstract]
Revenues									14,129,000	15,954,000		14,060,000
Segment Operating Earnings (loss)									(2,113,000)	(3,632,000)	[1]	(13,874,000)	[1]
Depreciation Depletion and Amortization									7,494,000	8,848,000		8,249,000
Property and Equipment Additions									13,094,000	23,083,000		24,580,000
Gain on property sale										2,203,000		2,923,000
Segment operating earnings [Abstract]
Segment operating earnings									(2,113,000)	(3,632,000)	[1]	(13,874,000)	[1]
Identifiable assets by segment [Abstract]
Assets	37,093,000				35,788,000				37,093,000	35,788,000		29,105,000
Other [Member]
Identifiable assets by segment [Abstract]
Assets	$ 69,890,000				$ 66,853,000				$ 69,890,000	$ 66,853,000		$ 68,697,000

[1] Oil and gas segment operating earnings include gains on property sales totaling $2,203,000 and $2,923,000 during 2012 and 2011, respectively.