GOODWILL AND INTANGIBLE ASSETS - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Changes in the carrying amount of goodwill
Balance at the beginning of the period	$ 993,375	$ 821,500
Acquisition	10,626	172,632
Purchase price adjustments	(5,253)	(757)
Balance at the end of the period	998,748	993,375
Domestic Pipelines & Terminals
Changes in the carrying amount of goodwill
Balance at the beginning of the period	279,280	279,615
Acquisition	10,626	0
Purchase price adjustments	0	(335)
Balance at the end of the period	289,906	279,280
Global Marine Terminals
Changes in the carrying amount of goodwill
Balance at the beginning of the period	709,596	537,894
Acquisition	0	172,632
Purchase price adjustments	(5,253)	(930)
Balance at the end of the period	704,343	709,596
Merchant Services
Changes in the carrying amount of goodwill
Balance at the beginning of the period	4,499	3,991
Acquisition	0	0
Purchase price adjustments	0	508
Balance at the end of the period	$ 4,499	$ 4,499