Derivative Instruments - Gain (Loss) for Derivative Instruments Not Designated or Qualifying as Hedging Instruments (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative [Line Items]
Realized gains (losses)	$ (114)	$ 800	$ 360	$ 1,741
Unrealized (losses) gains	(475)	(2,578)	(1,776)	(4,366)
Total	(589)	(1,778)	(1,416)	(2,625)
Interest rate swap agreement
Derivative [Line Items]
Realized gains (losses)	86	829	609	1,783
Unrealized (losses) gains	(483)	(2,699)	(1,697)	(4,470)
Total	(397)	(1,870)	(1,088)	(2,687)
Forward freight agreements
Derivative [Line Items]
Realized gains (losses)	(200)	(29)	(249)	(42)
Unrealized (losses) gains	8	121	(79)	104
Total	$ (192)	$ 92	$ (328)	$ 62

Derivative instruments not designated as hedging instruments realized gain (loss) net.

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- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CC
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109998890-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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