Intangible Assets (Tables)

9 Months Ended

Sep. 30, 2018

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, 2018						December 31, 2017
	Gross Carrying Amount		Accumulated Amortization		Carrying Value		Gross Carrying Amount		Accumulated Amortization		Carrying Value
Sodium minerals and sulfur services:
Customer relationships	$	94,654	$	94,114	$	540	$	94,654	$	92,493	$	2,161
Licensing agreements	38,678		38,141		537		38,678		36,528		2,150
Non-compete agreement	800		289		511		800		89		711
Segment total	134,132		132,544		1,588		134,132		129,110		5,022
Onshore Facilities & Transportation:
Customer relationships	35,430		35,113		317		35,430		35,082		348
Intangibles associated with lease	13,260		5,288		7,972		13,260		4,933		8,327
Segment total	48,690		40,401		8,289		48,690		40,015		8,675
Marine contract intangibles	27,000		15,750		11,250		27,000		11,700		15,300
Offshore pipeline contract intangibles	158,101		26,350		131,751		158,101		20,109		137,992
Other	31,149		15,736		15,413		28,900		13,483		15,417
Total	$	399,072	$	230,781	$	168,291	$	396,823	$	214,417	$	182,406

Schedule of Amortization Expense

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2018		2017		2018		2017
Amortization of intangible assets	$	5,475	$	5,879	$	16,369	$	17,623

Schedule of Expected Amortization Expense

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

Remainder of	2018	$	5,503
	2019	$	17,679
	2020	$	16,665
	2021	$	10,867
	2022	$	10,708