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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

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- Definition

This item represents the entity's ownership percentage in the investee multiplied by the investee's total equity.

+ 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
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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.

+ Details

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Investment in Unconsolidated Companies (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Sonatide Marine, Ltd.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in unconsolidated affiliates	49.00%
DTDW Holdings, Ltd.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in unconsolidated affiliates	40.00%
Investments in, at equity, and advances to unconsolidated companies		$ 1,033
GulfMark Marine, Ltd.
Schedule of Equity Method Investments [Line Items]
Ownership percentage in unconsolidated affiliates	49.00%
Investments in, at equity, and advances to unconsolidated companies		6
Sonatide Marine Ltd and DTDW Holdings Ltd.
Schedule of Equity Method Investments [Line Items]
Investments in, at equity, and advances to unconsolidated companies		$ 1,039