SEGMENT DATA (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Segment	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
SEGMENT DATA [Abstract]
Number of reportable segments | Segment			2
Revenues [Abstract]
Revenues	$ 666,809,000	$ 704,845,000	$ 2,182,472,000	$ 2,249,204,000
Segment profit (loss)	64,455,000	57,066,000	185,501,000	144,451,000
Total assets	6,127,885,000		6,127,885,000		$ 5,871,594,000
Other segment disclosures [Abstract]
Gain (loss) on disposition of assets	(374,000)	18,000	4,901,000	2,358,000
Interest expense	(14,310,000)	(12,345,000)	(43,026,000)	(34,665,000)
Other income	864,000	1,454,000	2,677,000	4,586,000
Earnings before taxes on income	64,455,000	57,066,000	185,501,000	144,451,000
Marine Transportation [Member]
Revenues [Abstract]
Revenues	412,665,000	382,040,000	1,185,072,000	1,100,606,000
Distribution and Services [Member]
Revenues [Abstract]
Revenues	254,144,000	322,805,000	997,400,000	1,148,598,000
Other [Member]
Revenues [Abstract]
Segment profit (loss)	(17,374,000)	(15,365,000)	(45,732,000)	(59,543,000)
Total assets	100,084,000		100,084,000		72,664,000
Other segment disclosures [Abstract]
General corporate expenses	(3,554,000)	(4,492,000)	(10,284,000)	(31,822,000)
Gain (loss) on disposition of assets	(374,000)	18,000	4,901,000	2,358,000
Interest expense	(14,310,000)	(12,345,000)	(43,026,000)	(34,665,000)
Other income	864,000	1,454,000	2,677,000	4,586,000
Earnings before taxes on income	(17,374,000)	(15,365,000)	(45,732,000)	(59,543,000)
Details of "Other" total assets [Abstract]
General corporate assets	98,205,000		98,205,000		70,169,000
Investment in affiliates	1,879,000		1,879,000		2,495,000
Total other assets	100,084,000		100,084,000		72,664,000
Reporting Segments [Member] | Marine Transportation [Member]
Revenues [Abstract]
Revenues	412,665,000	382,040,000	1,185,072,000	1,100,606,000
Segment profit (loss)	72,697,000	48,517,000	161,364,000	102,925,000
Total assets	4,538,771,000		4,538,771,000		4,145,294,000
Other segment disclosures [Abstract]
Earnings before taxes on income	72,697,000	48,517,000	161,364,000	102,925,000
Reporting Segments [Member] | Distribution and Services [Member]
Revenues [Abstract]
Revenues	254,144,000	322,805,000	997,400,000	1,148,598,000
Segment profit (loss)	9,132,000	23,914,000	69,869,000	101,069,000
Total assets	1,489,030,000		1,489,030,000		$ 1,653,636,000
Other segment disclosures [Abstract]
Earnings before taxes on income	9,132,000	23,914,000	69,869,000	101,069,000
Intersegment Eliminations [Member]
Revenues [Abstract]
Revenues	7,201,000	5,837,000	22,182,000	21,757,000
Segment profit (loss)	720,000	584,000	2,218,000	2,176,000
Other segment disclosures [Abstract]
Earnings before taxes on income	$ 720,000	$ 584,000	$ 2,218,000	$ 2,176,000