Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Activities by Segment [Abstract]
Revenues	$ 1,060,770	$ 795,525	$ 2,980,145	$ 2,504,488
Segment operating earnings (loss)	13,270	16,373	40,873	39,015
Depreciation Depletion and Amortization	5,373	5,450	16,294	14,639
Property and Equipment Additions	6,835	11,519	23,133	43,129
Segment operating earnings [Abstract]
General and administrative expenses	(2,535)	(2,603)	(7,504)	(7,300)
Operating earnings	10,735	13,770	33,369	31,715
Interest income	33	78	103	120
Interest expense	(1)	(1)	(24)	(4)
Earnings from continuing operations before income taxes	10,767	13,847	33,448	31,831
Identifiable assets by segment [Abstract]
Assets	474,680		474,680		419,501
Marketing [Member]
Activities by Segment [Abstract]
Revenues	1,039,767	774,732	2,917,328	2,442,884
Segment operating earnings (loss)	11,270	13,452	35,398	30,937
Depreciation Depletion and Amortization	1,939	1,611	5,664	4,340
Property and Equipment Additions	932	1,673	9,512	9,079
Identifiable assets by segment [Abstract]
Assets	338,389		338,389		289,684
Marketing [Member] | Crude Oil [Member]
Activities by Segment [Abstract]
Revenues	1,039,337	773,611	2,915,056	2,438,815
Segment operating earnings (loss)	11,394	13,278	35,509	29,880
Depreciation Depletion and Amortization	1,939	1,596	5,517	4,324
Property and Equipment Additions	932	1,673	9,512	9,079
Identifiable assets by segment [Abstract]
Assets	329,893		329,893		277,920
Marketing [Member] | Natural Gas [Member]
Activities by Segment [Abstract]
Revenues	430	1,121	2,272	4,069
Segment operating earnings (loss)	(124)	174	(111)	1,057
Depreciation Depletion and Amortization	0	15	147	16
Property and Equipment Additions	0	0	0	0
Identifiable assets by segment [Abstract]
Assets	8,496		8,496		11,764
Transportation [Member]
Activities by Segment [Abstract]
Revenues	16,906	16,741	51,795	50,137
Segment operating earnings (loss)	1,248	2,607	4,479	7,919
Depreciation Depletion and Amortization	1,787	1,574	5,263	4,186
Property and Equipment Additions	1,589	4,740	3,162	15,484
Identifiable assets by segment [Abstract]
Assets	37,019		37,019		38,940
Oil and Gas [Member]
Activities by Segment [Abstract]
Revenues	4,097	4,052	11,022	11,467
Segment operating earnings (loss)	752	314	996	159
Depreciation Depletion and Amortization	1,647	2,265	5,367	6,113
Property and Equipment Additions	4,314	5,106	10,459	18,566
Identifiable assets by segment [Abstract]
Assets	38,962		38,962		35,788
Other [Member]
Identifiable assets by segment [Abstract]
Assets	$ 60,310		$ 60,310		$ 55,089