Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Voyage revenues	$ 601,256	$ 510,762	$ 432,676
Operating Costs and Expenses	111,585	117,658	101,539
Time-charter hire expense	(19,994)	(7,670)	0
General and administrative expenses	(22,521)	(28,512)	(18,141)
Restructuring charges	3,315	1,845	0
Advances to affiliates
Related Party Transaction [Line Items]
Voyage revenues	49,257	19,612	36,358
Operating Costs and Expenses	6,629	17,852	23,564
Time-charter hire expense	(19,994)	(7,670)	0
General and administrative expenses	(15,393)	(15,395)	(9,434)
Employee severance
Related Party Transaction [Line Items]
Restructuring charges	2,900	1,800
Employee severance \| Advances to affiliates
Related Party Transaction [Line Items]
Restructuring charges	$ 400	$ 0	$ 0

The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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