Segments (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting Information [Line Items]
Depreciation and amortization	$ 12,636	$ 11,892
Revenues	287,696	312,031
Costs and Expenses	282,651	311,067
Operating Income (Loss)	22,390	8,462
Income (loss) from continuing operations before income taxes	(5,472)	846
SemCrude [Member]
Segment Reporting Information [Line Items]
Revenues	171,232	179,715
Costs and Expenses	161,546	171,647
Operating Income (Loss)	20,115	14,639
Income (loss) from continuing operations before income taxes	16,944	14,876
SemStream [Member]
Segment Reporting Information [Line Items]
Revenues	0	6
Costs and Expenses	163	79
Operating Income (Loss)	6,753	854
Income (loss) from continuing operations before income taxes	7,721	816
Decrease to previously reported balances due to discontinued operations | SemStream [Member]
Segment Reporting Information [Line Items]
Revenues		5,600
Costs and Expenses		5,400
Operating Income (Loss)		300
Income (loss) from continuing operations before income taxes		$ 300