CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shipping Revenues:
Shipping revenues	$ 366,184	$ 270,361	$ 290,101
Operating Expenses:
Voyage expenses	26,265	27,261	15,106
Vessel expenses	123,205	135,003	141,235
Charter hire expenses	57,512	44,910	41,700
Depreciation and amortization	75,653	72,428	78,853
General and administrative	26,798	24,304	24,453
Provision for credit losses	1,245
Third-party debt modification fees	30	1,306	9,240
Separation and transition costs			604
Loss on disposal of vessels and other property, including impairments	308	19,680	86,855
Total operating expenses	311,016	324,892	398,046
Income/(loss) from vessel operations	55,168	(54,531)	(107,945)
Equity in income of affiliated companies	11,213	29,432	48,966
Operating income/(loss)	66,381	(25,099)	(58,979)
Other income/(loss)	(943)	(3,715)	(5,818)
Income/(loss) before interest expense and income taxes	65,438	(28,814)	(64,797)
Interest expense	(66,267)	(60,231)	(41,247)
Loss before income taxes	(829)	(89,045)	(106,044)
Income tax benefit/(provision)	(1)	105	(44)
Net loss	$ (830)	$ (88,940)	$ (106,088)
Weighted Average Number of Common Shares Outstanding:
Basic and diluted	29,225,483	29,136,634	29,159,440
Per Share Amounts:
Basic and diluted net loss per share	$ (0.03)	$ (3.05)	$ (3.64)
Pool Revenue Leases [Member]
Shipping Revenues:
Shipping revenues	$ 254,055	$ 177,206	$ 177,347
Time and Bareboat Charter Leases [Member]
Shipping Revenues:
Shipping revenues	27,625	25,961	55,106
Voyage Charter Leases [Member]
Shipping Revenues:
Shipping revenues	$ 84,504	$ 67,194	$ 57,648