Related Party Transactions - Schedule of the impact of Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Terminalling and storage	$ 20,025	$ 19,704
Marine transportation	3,613	4,325
Natural gas services	0	112
Product sales:
Product sales related party	642	1,430
Cost of products sold:
Natural gas services	4,318	8,894
Sulfur services	4,526	3,675
Terminalling and storage	6,558	5,067
Operating expenses:
Operating expenses	13,384	16,376
Related Party
Product sales:
Product sales related party	642	1,430
Revenue from related parties	24,280	25,571
Cost of products sold:
Cost of products sold	15,402	17,636
Operating expenses:
Operating expenses	13,384	16,376
Selling, general and administrative:
Selling, general and administrative	7,721	7,568
Related Party | Terminalling and storage
Revenues:
Terminalling and storage	20,025	19,704
Product sales:
Product sales related party	255	57
Cost of products sold:
Terminalling and storage	6,558	5,067
Operating expenses:
Operating expenses	4,525	6,699
Selling, general and administrative:
Selling, general and administrative	681	543
Related Party | Marine transportation
Revenues:
Marine transportation	3,613	4,325
Operating expenses:
Operating expenses	5,321	5,996
Selling, general and administrative:
Selling, general and administrative	8	8
Related Party | Natural gas services
Revenues:
Natural gas services	0	112
Product sales:
Product sales related party	1	942
Cost of products sold:
Natural gas services	4,318	8,894
Operating expenses:
Operating expenses	2,199	2,235
Selling, general and administrative:
Selling, general and administrative	2,254	2,277
Related Party | Sulfur services
Product sales:
Product sales related party	386	431
Cost of products sold:
Sulfur services	4,526	3,675
Operating expenses:
Operating expenses	1,339	1,446
Selling, general and administrative:
Selling, general and administrative	659	636
Related Party | Indirect, including overhead allocation
Selling, general and administrative:
Selling, general and administrative	$ 4,119	$ 4,104