Reportable Segments (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Sales		$ 247,095	$ 270,252	$ 440,852	$ 515,357
Operating Income (Loss)		34,939	25,129	34,976	40,086
Energy & Chemicals [Member]
Segment Reporting Information [Line Items]
Sales		61,195	91,339	99,154	178,809
Operating Income (Loss)	[1]	22,124	19,540	19,926	34,831
Distribution & Storage [Member]
Segment Reporting Information [Line Items]
Sales		129,600	121,813	237,097	226,884
Operating Income (Loss)	[1]	13,005	10,845	22,835	21,157
BioMedical [Member]
Segment Reporting Information [Line Items]
Sales		56,300	57,100	104,601	109,664
Operating Income (Loss)	[1]	10,552	6,000	17,204	9,236
Corporate [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	[1]	$ (10,742)	$ (11,256)	$ (24,989)	$ (25,138)

[1] As described in Note 1, beginning in 2016, the Company allocates share-based compensation expense to each operating segment and maintains share-based compensation expense related to Corporate employees at Corporate. Prior to 2016, all share-based compensation expense was recorded at Corporate. Reclassifications from Corporate to the operating segments have been made to the 2015 results to conform to the 2016 presentation.