SEGMENT DATA (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) Segment	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
SEGMENT DATA [Abstract]
Number of reportable segments | Segment			2
Revenues [Abstract]
Revenues	$ 704,845	$ 541,274	$ 2,249,204	$ 1,506,307
Segment profit (loss)	57,066	47,861	144,451	131,874
Total assets	5,854,332		5,854,332		$ 5,127,427
Other segment disclosures [Abstract]
Gain (loss) on disposition of assets	18	(159)	2,358	(199)
Interest expense	(12,345)	(5,388)	(34,665)	(14,310)
Other income (expense)	1,454	320	4,586	(41)
Executive Chairman [Member]
Other segment disclosures [Abstract]
General corporate expenses			18,057
Marine Transportation [Member]
Revenues [Abstract]
Revenues	382,040	318,810	1,100,606	993,727
Distribution and Services [Member]
Revenues [Abstract]
Revenues	322,805	222,464	1,148,598	512,580
Other [Member]
Revenues [Abstract]
Segment profit (loss)	(15,365)	(9,735)	(59,543)	(27,101)
Total assets	61,411		61,411		75,243
Other segment disclosures [Abstract]
General corporate expenses	(4,492)	(4,508)	(31,822)	(12,551)
Gain (loss) on disposition of assets	18	(159)	2,358	(199)
Interest expense	(12,345)	(5,388)	(34,665)	(14,310)
Other income (expense)	1,454	320	4,586	(41)
Loss from other segment	(15,365)	(9,735)	(59,543)	(27,101)
Details of "Other" total assets [Abstract]
General corporate assets	59,229		59,229		73,353
Investment in affiliates	2,182		2,182		1,890
Total other assets	61,411		61,411		75,243
Reporting Segments [Member] | Marine Transportation [Member]
Revenues [Abstract]
Revenues	382,040	318,810	1,100,606	993,727
Segment profit (loss)	48,517	35,649	102,925	106,992
Total assets	4,191,514		4,191,514		3,485,099
Reporting Segments [Member] | Distribution and Services [Member]
Revenues [Abstract]
Revenues	322,805	222,464	1,148,598	512,580
Segment profit (loss)	23,914	21,947	101,069	51,983
Total assets	1,601,407		1,601,407		$ 1,567,085
Intersegment Eliminations [Member]
Revenues [Abstract]
Revenues	5,837	4,967	21,757	15,342
Segment profit (loss)	$ 584	$ 497	$ 2,176	$ 1,534