Reportable Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012 segments	Jun. 30, 2011	Jun. 30, 2012 segments	Jun. 30, 2011
Segment Reporting Information [Line Items]
Number of reportable segments	3		3
Sales	$ 239,939	$ 200,698	$ 456,045	$ 363,639
Operating income (loss)	33,083	21,489	56,944	35,796
Energy & Chemicals [Member]
Segment Reporting Information [Line Items]
Sales	77,129	49,121	145,953	91,637
Operating income (loss)	14,536	5,605	27,728	9,357
Distribution & Storage [Member]
Segment Reporting Information [Line Items]
Sales	113,434	101,682	218,526	175,055
Operating income (loss)	17,674	17,102	34,499	28,622
BioMedical [Member]
Segment Reporting Information [Line Items]
Sales	49,376	49,895	91,566	96,947
Operating income (loss)	11,948	7,223	18,447	15,670
Corporate [Member]
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Operating income (loss)	$ (11,075)	$ (8,441)	$ (23,730)	$ (17,853)