Equity-Accounted Joint Ventures - Angola Joint Venture - Additional Information (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($) vessel m³	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in joint venture	100.00%
Angola Joint Venture
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in joint venture	33.00%
Principal amount outstanding on secured loan facilities and finance leases	$ 213.8
Number of vessels \| vessel	4
Volume of vessels (in cubic meter) \| m³	160,400
Carrying value of guarantee liability	$ 0.5	$ 0.6
Angola Joint Venture \| NYK Energy Transport
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in joint venture	33.00%
Angola Joint Venture \| Mitsui & Co. Ltd
Schedule of Equity Method Investments [Line Items]
Percentage of ownership in joint venture	34.00%

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
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The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
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-Section 50
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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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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.

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