ACCUMULATED OTHER COMPREHENSIVE LOSS (Amounts Reclassified out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (Loss)/Income from Discontinued Operations					$ (340,153)	$ (45,884)	$ 34,045	$ 59,437	$ 0	$ (292,555)	$ 203,395
Interest expense	$ 9,125	$ 9,474	$ 9,445	$ 9,357	$ 9,765	$ 10,607	$ 10,862	$ 11,917	37,401	43,151	70,365
General and administrative									27,493	41,608	61,540
Vessel expenses									135,991	140,696	138,179
Total before tax									(1,937)	(17,290)	(18,738)
Tax provision									677	297	223
Total net of tax									(1,260)	(16,993)	(18,515)
Unrealized losses on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax provision									(513)	(118)	0
Total net of tax									(907)	(16,293)	(18,104)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment Attributable To Parent For Shore Based Employees [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (Loss)/Income from Discontinued Operations									0	(365)	(482)
General and administrative									(666)	(645)	(232)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment Attributable To Parent For Seagoing Employees [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Vessel expenses									150	131	80
Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Swap Entered Into By Joint Ventures Investees [Member] | Unrealized losses on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (Loss)/Income from Discontinued Operations									0	(15,664)	(18,101)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Cap Entered Into By Subsidiaries [Member] | Unrealized losses on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net (Loss)/Income from Discontinued Operations									0	(408)	(2)
Interest expense									$ (1,421)	$ (339)	$ (1)