Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Activities by Segment [Abstract]
Revenues	$ 795,525	$ 755,995	$ 2,504,488	$ 2,197,379
Segment Operating Earnings	16,373	16,671	39,015	35,491
Depreciation Depletion and Amortization	5,450	3,953	14,639	11,061
Property and Equipment Additions	11,519	10,933	43,129	41,206
Segment operating earnings [Abstract]
Segment operating earnings (loss)	16,373	16,671	39,015	35,491
General and administrative	(2,603)	(2,727)	(7,300)	(7,324)
Operating earnings	13,770	13,944	31,715	28,167
Interest income	78	142	120	233
Interest expense	(1)	0	(4)	(7)
Earnings from continuing operations before income taxes and discontinued operations	13,847	14,086	31,831	28,393
Identifiable assets by segment [Abstract]
Assets	388,655		388,655		378,840
Marketing [Member]
Activities by Segment [Abstract]
Revenues	774,732	737,077	2,442,884	2,137,741
Segment Operating Earnings	13,452	16,055	30,937	28,075
Depreciation Depletion and Amortization	1,611	1,028	4,340	2,568
Property and Equipment Additions	1,673	1,945	9,079	10,629
Segment operating earnings [Abstract]
Segment operating earnings (loss)	13,452	16,055	30,937	28,075
Identifiable assets by segment [Abstract]
Assets	248,500		248,500		266,063
Marketing [Member] | Crude Oil [Member]
Activities by Segment [Abstract]
Revenues	773,611	735,514	2,438,815	2,133,485
Segment Operating Earnings	13,278	15,401	29,880	26,341
Depreciation Depletion and Amortization	1,596	1,027	4,324	2,565
Property and Equipment Additions	1,673	1,937	9,079	10,565
Segment operating earnings [Abstract]
Segment operating earnings (loss)	13,278	15,401	29,880	26,341
Identifiable assets by segment [Abstract]
Assets	238,930		238,930		253,817
Marketing [Member] | Natural Gas [Member]
Activities by Segment [Abstract]
Revenues	1,121	1,563	4,069	4,256
Segment Operating Earnings	174	654	1,057	1,734
Depreciation Depletion and Amortization	15	1	16	3
Property and Equipment Additions	0	8	0	64
Segment operating earnings [Abstract]
Segment operating earnings (loss)	174	654	1,057	1,734
Identifiable assets by segment [Abstract]
Assets	9,570		9,570		12,246
Transportation [Member]
Activities by Segment [Abstract]
Revenues	16,741	15,398	50,137	49,547
Segment Operating Earnings	2,607	2,078	7,919	7,003
Depreciation Depletion and Amortization	1,574	1,041	4,186	2,915
Property and Equipment Additions	4,740	682	15,484	9,810
Segment operating earnings [Abstract]
Segment operating earnings (loss)	2,607	2,078	7,919	7,003
Identifiable assets by segment [Abstract]
Assets	41,155		41,155		27,221
Oil and Gas [Member]
Activities by Segment [Abstract]
Revenues	4,052	3,520	11,467	10,091
Segment Operating Earnings	314	(1,462)	159	413
Depreciation Depletion and Amortization	2,265	1,884	6,113	5,578
Property and Equipment Additions	5,106	8,306	18,566	20,701
Segment operating earnings [Abstract]
Segment operating earnings (loss)	314	(1,462)	159	413
Identifiable assets by segment [Abstract]
Assets	40,531		40,531		29,105
Other [Member]
Identifiable assets by segment [Abstract]
Assets	$ 58,469		$ 58,469		$ 56,451