Disposition gains are sales of operating assets

No definition available.

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- Definition

gmt_Number of Sold Vessels

+ References

No definition available.

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- Definition

Portfolio proceeds.

+ References

No definition available.

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

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- Definition

Fair value portion of assets classified as held for sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19190-110258

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

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- Definition

The cash inflow associated with the sale of equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

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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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Assets Held For Sale Assets Held For Sale (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($) Vessel	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Asset impairment		$ 31.1	$ 1.8	$ 31.2
Assets Held-for-sale, Long Lived, Fair Value Disclosure	$ 62.1		62.1		$ 106.0
Portfolio Proceeds			170.6	298.2
Disposition gains on owned assets	11.6	$ 17.4	36.7	60.4
Portfolio Management [Member]
Segment Reporting Information [Line Items]
gmt_Number of Sold Vessels \| Vessel		6
Asset impairment		$ 31.0	1.8	31.0
Assets Held-for-sale, Long Lived, Fair Value Disclosure	60.5		60.5		$ 103.4
Portfolio Proceeds			49.4
Disposition gains on owned assets	$ (0.3)	7.2	4.2	9.3
Cardinal Marine [Domain]
Segment Reporting Information [Line Items]
Asset impairment		$ (19.0)		$ (19.0)
Noncontrolling Interest, Ownership Percentage by Parent		50.00%		50.00%
Nordic Vessels [Member] \| Portfolio Management [Member]
Segment Reporting Information [Line Items]
Asset impairment			0.0
Cardinal Marine [Domain] \| Portfolio Management [Member]
Segment Reporting Information [Line Items]
Proceeds from Sale of Equity Method Investments			$ 1.0