Goodwill and Intangible Assets Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Beginning Balance, Goodwill	$ 217,970
Goodwill, Translation and Purchase Accounting Adjustments	1,418
Goodwill, Acquired During Period	8,849
Ending Balance, Goodwill	228,237
Goodwill, Impaired, Accumulated Impairment Loss	195,846	$ 195,846
Energy & Chemicals [Member]
Goodwill [Roll Forward]
Beginning Balance, Goodwill	27,873
Goodwill, Translation and Purchase Accounting Adjustments	0
Goodwill, Acquired During Period	8,849
Ending Balance, Goodwill	36,722
Goodwill, Impaired, Accumulated Impairment Loss	64,603	64,603
Distribution & Storage [Member]
Goodwill [Roll Forward]
Beginning Balance, Goodwill	165,520
Goodwill, Translation and Purchase Accounting Adjustments	1,522
Goodwill, Acquired During Period	0
Ending Balance, Goodwill	167,042
Goodwill, Impaired, Accumulated Impairment Loss	0	0
BioMedical [Member]
Goodwill [Roll Forward]
Beginning Balance, Goodwill	24,577
Goodwill, Translation and Purchase Accounting Adjustments	104
Goodwill, Acquired During Period	0
Ending Balance, Goodwill	24,473
Goodwill, Impaired, Accumulated Impairment Loss	$ 131,243	$ 131,243