For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Summary of Significant Accounting Policies - Major Charterers (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Hyundai Merchant Marine Co. Ltd.
Entity Wide Revenue Major Customer [Line Items]
Customer revenue percentage	25.90%	24.50%	26.80%
Yang Ming Marine Transport Corporation
Entity Wide Revenue Major Customer [Line Items]
Customer revenue percentage			12.00%
Swissmarine Asia Pte LTD
Entity Wide Revenue Major Customer [Line Items]
Customer revenue percentage	12.30%
Cargill International SA
Entity Wide Revenue Major Customer [Line Items]
Customer revenue percentage	10.90%