Intangible Assets (Tables)

6 Months Ended

Jun. 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:

	June 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	$	93,574	$	1,080	$	94,654	$	92,493	$	2,161
Licensing agreements	38,678		37,603		1,075		38,678		36,528		2,150
Non-compete agreement	800		222		578		800		89		711
Segment total	134,132		131,399		2,733		134,132		129,110		5,022
Onshore Facilities & Transportation:
Customer relationships	35,430		35,103		327		35,430		35,082		348
Intangibles associated with lease	13,260		5,170		8,090		13,260		4,933		8,327
Segment total	48,690		40,273		8,417		48,690		40,015		8,675
Marine contract intangibles	27,000		14,400		12,600		27,000		11,700		15,300
Offshore pipeline contract intangibles	158,101		24,270		133,831		158,101		20,109		137,992
Other	31,074		14,970		16,104		28,900		13,483		15,417
Total	$	398,997	$	225,312	$	173,685	$	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 June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Amortization of intangible assets	$	5,461	$	5,872	$	10,894	$	11,744

Schedule of Expected Amortization Expense

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

Remainder of	2018	$	11,003
	2019	$	16,155
	2020	$	16,750
	2021	$	11,378
	2022	$	10,768