2017 AND 2016 QUARTERLY RESULTS OF OPERATIONS (Schedule of Quarterly Financial Information) (Details) - USD ($)	1 Months Ended	3 Months Ended								12 Months Ended
	Nov. 30, 2016	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
Quarterly Financial Information [Line Items]
Shipping revenues		$ 92,815,000	$ 93,270,000	$ 96,225,000	$ 108,116,000	$ 114,776,000	$ 114,180,000	$ 118,384,000	$ 115,080,000	$ 390,426,000	$ 462,420,000	$ 466,872,000
Gain/(loss) on disposal of vessels, including impairments		5,847,000	7,353,000	0	0	(6,623,000)	(97,782,000)	(113,000)	(14,000)	(13,200,000)	(104,532,000)	(207,000)
Income/(loss) from vessel operations		164,000	434,000	14,220,000	19,258,000	7,821,000	(83,439,000)	23,035,000	17,401,000	34,076,000	(35,182,000)	80,406,000
Interest expense		(9,125,000)	(9,474,000)	(9,445,000)	(9,357,000)	(9,765,000)	(10,607,000)	(10,862,000)	(11,917,000)	(37,401,000)	(43,151,000)	(70,365,000)
Reorganization items, net		8,000	46,000	(9,000)	(235,000)	(393,000)	(5,732,000)	(860,000)	17,910,000	(190,000)	10,925,000	(8,052,000)
Income tax benefit/(provision)		59,679,000	3,110,000	(1,593,000)	(3,569,000)	63,653,000	49,755,000	(15,075,000)	(33,235,000)	57,627,000	65,098,000	101,032,000
Net income/(loss) from continuing operations						64,678,000	(52,855,000)	(4,184,000)	(8,698,000)	55,978,000	(1,059,000)	80,565,000
Net (Loss)/Income from discontinued operations						(340,153,000)	(45,884,000)	34,045,000	59,437,000	0	(292,555,000)	203,395,000
Net income/(loss)		53,645,000	$ (6,307,000)	$ 3,211,000	$ 5,429,000	$ (275,475,000)	$ (98,739,000)	$ 29,861,000	$ 50,739,000	55,978,000	(293,614,000)	283,960,000
Tax cuts and jobs act Of 2017, incomplete accounting, provisional income tax expense (benefit)		$ (54,300,000)								(54,300,000)
Equity method investment, other than temporary impairment	$ 332,562,000
Common Class B [Member]
Quarterly Financial Information [Line Items]
Net income/(loss) from continuing operations										0	(57,000)	1,097,000
Net (Loss)/Income from discontinued operations										$ 0	$ 2,426,000	$ 2,770,000
Basic and Diluted net income/(loss) per share, continuing operations						$ 0.00	$ 0.00	$ (0.27)	$ (0.09)	$ 0.00	$ (0.11)	$ 0.83
Basic and Diluted net income/(loss) per share, discontinued operations						0.00	0.00	2.19	0.64	$ 0.00	$ 4.54	$ 2.10
Common Class A [Member]
Quarterly Financial Information [Line Items]
Net income/(loss) from continuing operations										$ 55,957,000	$ (1,002,000)	$ 79,424,000
Net (Loss)/Income from discontinued operations										$ 0	$ (295,001,000)	$ 200,515,000
Basic and Diluted net income/(loss) per share, continuing operations		$ 0.61	$ (0.07)	$ 0.04	$ 0.06	0.74	(0.59)	(0.04)	(0.09)	$ 0.64	$ (0.01)	$ 0.83
Basic and Diluted net income/(loss) per share, discontinued operations						$ (3.89)	$ (0.51)	$ 0.35	$ 0.62	$ 0.00	$ (3.24)	$ 2.10