Intangible Assets, Goodwill and Other Assets (Schedule of Estimated Amortization Expense) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Finite-Lived Intangible Assets [Line Items]
2018	$ 21,788
2019	17,453
2020	16,431
2021	10,642
2022	10,482
Other
Finite-Lived Intangible Assets [Line Items]
2018	2,974
2019	2,952
2020	2,921
2021	1,810
2022	1,652
Sodium Minerals and Sulfur Services \| Customer relationships
Finite-Lived Intangible Assets [Line Items]
2018	2,161
2019	0
2020	0
2021	0
2022	0
Sodium Minerals and Sulfur Services \| Licensing agreements
Finite-Lived Intangible Assets [Line Items]
2018	2,150
2019	0
2020	0
2021	0
2022	0
Sodium Minerals and Sulfur Services \| Non-compete agreement
Finite-Lived Intangible Assets [Line Items]
2018	267
2019	267
2020	177
2021	0
2022	0
Onshore Facilities and Transportation \| Customer relationships
Finite-Lived Intangible Assets [Line Items]
2018	41
2019	39
2020	38
2021	37
2022	35
Onshore Facilities and Transportation \| Intangibles associated with lease
Finite-Lived Intangible Assets [Line Items]
2018	474
2019	474
2020	474
2021	474
2022	474
Marine Transportation
Finite-Lived Intangible Assets [Line Items]
2018	5,400
2019	5,400
2020	4,500
2021	0
2022	0
Offshore Pipeline Transportation
Finite-Lived Intangible Assets [Line Items]
2018	8,321
2019	8,321
2020	8,321
2021	8,321
2022	$ 8,321

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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