Intangible Assets (Tables)

9 Months Ended

Sep. 30, 2017

Intangible Assets, Net (Excluding Goodwill) [Abstract]

Schedule of Components of Intangible Assets

The following table summarizes the components of our intangible assets at the dates indicated:

	September 30, 2017						December 31, 2016
	Gross Carrying Amount		Accumulated Amortization		Carrying Value		Gross Carrying Amount		Accumulated Amortization		Carrying Value
Sodium minerals and sulfur services:
Customer relationships	$	94,654	$	91,809	$	2,845	$	94,654	$	89,756	$	4,898
Licensing agreements	38,678		35,947		2,731		38,678		34,204		4,474
Segment total	133,332		127,756		5,576		133,332		123,960		9,372
Onshore Facilities & Transportation:
Customer relationships	35,430		34,731		699		35,430		33,676		1,754
Intangibles associated with lease	13,260		4,815		8,445		13,260		4,459		8,801
Segment total	48,690		39,546		9,144		48,690		38,135		10,555
Marine contract intangibles	27,000		10,350		16,650		27,000		6,300		20,700
Offshore pipeline contract intangibles	158,101		18,029		140,072		158,101		11,788		146,313
Other	28,747		12,748		15,999		28,569		10,622		17,947
Total	$	395,870	$	208,429	$	187,441	$	395,692	$	190,805	$	204,887

Amortization Expense

Our amortization of intangible assets for the periods presented was as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Amortization of intangible assets	$	5,879	$	6,122	$	17,623	$	18,154

Schedule of Expected Amortization Expense

We estimate that our amortization expense for the next five years will be as follows:

Remainder of	2017	$	5,919
	2018	$	21,506
	2019	$	17,171
	2020	$	16,237
	2021	$	10,627