ACCUMULATED OTHER COMPREHENSIVE LOSS (Changes in Components of AOCI, Net of Related Taxes) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	$ 254,332,000	$ 1,580,488,000	$ 1,286,087,000
Current period change, excluding amounts reclassified from accumulated other comprehensive loss	438,000	(10,037,000)	(8,596,000)
Amounts reclassified from accumulated other comprehensive loss	1,260,000	16,993,000	18,515,000
Distribution of International Seaways, Inc.		58,345,000
Other comprehensive income	1,698,000	6,956,000	9,919,000
Total change in accumulated other comprehensive loss		65,301,000
Balance	313,238,000	254,332,000	1,580,488,000
Unrealized losses on cash flow hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(1,019,000)	(54,620,000)	(61,547,000)
Current period change, excluding amounts reclassified from accumulated other comprehensive loss	0	(5,982,000)	(11,177,000)
Amounts reclassified from accumulated other comprehensive loss	907,000	16,293,000	18,104,000
Distribution of International Seaways, Inc.		43,290,000
Other comprehensive income	907,000		6,927,000
Total change in accumulated other comprehensive loss		53,601,000
Balance	(112,000)	(1,019,000)	(54,620,000)
Items not yet recognized as a component of net periodic benefit cost (pension and other postretirement plans)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(7,141,000)	(18,841,000)	(21,833,000)
Current period change, excluding amounts reclassified from accumulated other comprehensive loss	438,000	(4,055,000)	2,581,000
Amounts reclassified from accumulated other comprehensive loss	353,000	700,000	411,000
Distribution of International Seaways, Inc.		15,055,000
Other comprehensive income	791,000		2,992,000
Total change in accumulated other comprehensive loss		11,700,000
Balance	(6,350,000)	(7,141,000)	(18,841,000)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(8,160,000)	(73,461,000)	(83,380,000)
Other comprehensive income	1,698,000	6,956,000	9,919,000
Balance	$ (6,462,000)	$ (8,160,000)	$ (73,461,000)