Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Activities by Segment [Abstract]
Revenues	$ 965,874	$ 831,474	$ 1,919,375	$ 1,708,963
Segment operating earnings	12,739	11,028	27,603	22,642
Depreciation Depletion and Amortization	5,392	5,026	10,921	9,189
Property and Equipment Additions	12,395	16,388	16,298	31,610
Segment operating earnings [Abstract]
Segment operating earnings	12,739	11,028	27,603	22,642
General and administrative expenses	(2,703)	(2,465)	(4,969)	(4,697)
Operating earnings	10,036	8,563	22,634	17,945
Interest income	32	21	70	42
Interest expense	(21)	(2)	(23)	(3)
Earnings from continuing operations before income taxes	10,047	8,582	22,681	17,984
Identifiable assets by segment [Abstract]
Assets	427,217		427,217		419,501
Marketing [Member]
Activities by Segment [Abstract]
Revenues	944,619	810,722	1,877,561	1,668,152
Segment operating earnings	10,546	9,327	24,128	17,485
Depreciation Depletion and Amortization	1,946	1,438	3,725	2,729
Property and Equipment Additions	7,219	3,207	8,580	7,406
Segment operating earnings [Abstract]
Segment operating earnings	10,546	9,327	24,128	17,485
Identifiable assets by segment [Abstract]
Assets	309,436		309,436		289,684
Marketing [Member] | Crude Oil [Member]
Activities by Segment [Abstract]
Revenues	943,843	809,358	1,875,719	1,665,204
Segment operating earnings	10,681	8,837	24,115	16,602
Depreciation Depletion and Amortization	1,814	1,438	3,578	2,728
Property and Equipment Additions	7,219	3,207	8,580	7,406
Segment operating earnings [Abstract]
Segment operating earnings	10,681	8,837	24,115	16,602
Identifiable assets by segment [Abstract]
Assets	298,293		298,293		277,920
Marketing [Member] | Natural Gas [Member]
Activities by Segment [Abstract]
Revenues	776	1,364	1,842	2,948
Segment operating earnings	(135)	490	13	883
Depreciation Depletion and Amortization	132	0	147	1
Property and Equipment Additions	0	0	0	0
Segment operating earnings [Abstract]
Segment operating earnings	(135)	490	13	883
Identifiable assets by segment [Abstract]
Assets	11,143		11,143		11,764
Transportation [Member]
Activities by Segment [Abstract]
Revenues	17,543	17,128	34,889	33,396
Segment operating earnings	1,833	2,258	3,231	5,312
Depreciation Depletion and Amortization	1,740	1,361	3,476	2,612
Property and Equipment Additions	1,428	6,056	1,573	10,744
Segment operating earnings [Abstract]
Segment operating earnings	1,833	2,258	3,231	5,312
Identifiable assets by segment [Abstract]
Assets	37,393		37,393		38,940
Oil and Gas [Member]
Activities by Segment [Abstract]
Revenues	3,712	3,624	6,925	7,415
Segment operating earnings	360	(557)	244	(155)
Depreciation Depletion and Amortization	1,706	2,227	3,720	3,848
Property and Equipment Additions	3,748	7,125	6,145	13,460
Segment operating earnings [Abstract]
Segment operating earnings	360	(557)	244	(155)
Identifiable assets by segment [Abstract]
Assets	37,644		37,644		35,788
Other [Member]
Identifiable assets by segment [Abstract]
Assets	$ 42,744		$ 42,744		$ 55,089