Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Activities by Segment [Abstract]
Revenues	$ 876,476	$ 795,525	$ 831,474	$ 877,489	$ 847,609	$ 755,995	$ 777,538	$ 663,846	$ 3,380,964		$ 3,044,988		$ 2,083,781
Segment Operating Earnings (loss)									53,818		46,034		21,469
Depreciation Depletion and Amortization									20,714		15,885		11,314
Property and Equipment Additions									51,012		52,316		22,275
Gain on property sale									6,298		4,394		(94)
Segment operating earnings [Abstract]
Segment operating earnings									53,818		46,034		21,469
General and administrative expenses									(9,769)		(9,713)		(9,044)
Operating Earnings									44,049		36,321		12,425
Interest income									190		237		191
Interest expense									(10)		(8)		(36)
Earnings from continuing operations before income taxes and discontinued operations									44,229		36,550		12,580
Identifiable assets by segment [Abstract]
Assets	419,501				378,840				419,501		378,840		301,305
Marketing [Member]
Activities by Segment [Abstract]
Revenues									3,297,827		2,967,427		2,015,893
Segment Operating Earnings (loss)									47,166		51,384		16,603
Depreciation Depletion and Amortization									5,976		3,727		2,364
Property and Equipment Additions									12,391		13,618		6,166
Segment operating earnings [Abstract]
Segment operating earnings									47,166		51,384		16,603
Identifiable assets by segment [Abstract]
Assets	289,684				266,063				289,684		266,063		204,247
Marketing [Member] | Crude Oil [Member]
Activities by Segment [Abstract]
Revenues									3,292,948		2,961,176		2,005,301
Segment Operating Earnings (loss)									46,145		49,237		13,530
Depreciation Depletion and Amortization									5,945		3,724		2,320
Property and Equipment Additions									12,391		13,554		6,051
Segment operating earnings [Abstract]
Segment operating earnings									46,145		49,237		13,530
Identifiable assets by segment [Abstract]
Assets	277,920				253,817				277,920		253,817		184,299
Marketing [Member] | Natural Gas [Member]
Activities by Segment [Abstract]
Revenues									4,879		6,251		10,592
Segment Operating Earnings (loss)									1,021		2,147		3,073
Depreciation Depletion and Amortization									31		3		44
Property and Equipment Additions									0		64		115
Segment operating earnings [Abstract]
Segment operating earnings									1,021		2,147		3,073
Identifiable assets by segment [Abstract]
Assets	11,764				12,246				11,764		12,246		19,948
Transportation [Member]
Activities by Segment [Abstract]
Revenues									67,183		63,501		56,867
Segment Operating Earnings (loss)									10,253		8,521		6,623
Depreciation Depletion and Amortization									5,921		3,912		4,288
Property and Equipment Additions									15,538		14,118		4,410
Segment operating earnings [Abstract]
Segment operating earnings									10,253		8,521		6,623
Identifiable assets by segment [Abstract]
Assets	38,940				27,221				38,940		27,221		17,378
Oil and Gas [Member]
Activities by Segment [Abstract]
Revenues									15,954		14,060		11,021
Segment Operating Earnings (loss)									(3,601)	[1]	(13,871)	[1]	(1,757)
Depreciation Depletion and Amortization									8,817		8,246		4,662
Property and Equipment Additions									23,083		24,580		11,699
Gain on property sale									2,203		2,923
Segment operating earnings [Abstract]
Segment operating earnings									(3,601)	[1]	(13,871)	[1]	(1,757)
Identifiable assets by segment [Abstract]
Assets	35,788				29,105				35,788		29,105		32,563
Other [Member]
Identifiable assets by segment [Abstract]
Assets	$ 55,089				$ 56,451				$ 55,089		$ 56,451		$ 47,117

[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.