LEASES (Future Minimum Revenues on Charters-Out) (Details) - Charters-Out [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Operating Leases, Future Minimum Payments Receivable [Abstract]
2018	$ 177,283
2019	94,961
2020	43,570
2021	26,219
2022	30,675
Thereafter	77,464
Net minimum lease payments	$ 450,172
2018, revenue days	3002 days
2019, revenue days	1449 days
2020, revenue days	530 days
2021, revenue days	319 days
2022, revenue days	365 days
Thereafter, revenue days	886 days
Revenue days	6551 days