Segments (Details 1) (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
Segment Reporting Information [Line Items]
Total	$ (3,066)	$ 2,092	$ (92)	$ (1,012)	$ (5,592)	$ 1,334	$ 2,245	$ (297)	$ (2,078)	$ (2,310)	$ (6,320)
SemCAMS [Member]
Segment Reporting Information [Line Items]
Total									720	552	886
SemLogistics [Member]
Segment Reporting Information [Line Items]
Total									(7,736)	(3,331)	2,244
SemMexico [Member]
Segment Reporting Information [Line Items]
Total									2,285	629	259
Corporate and other [Member]
Segment Reporting Information [Line Items]
Total									$ 2,653	$ (160)	$ (9,709)