XML 149 R56.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Significant Accounting Policies (Gain on Asset Dispositions) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Significant Acquisitions and Disposals [Line Items] |  |  |
Disposition gains | $ 63.1 us-gaap_GainsLossesOnSalesOfAssets | $ 60.0 us-gaap_GainsLossesOnSalesOfAssets | $ 42.7 us-gaap_GainsLossesOnSalesOfAssets
Residual sharing income | 9.4 gmt_NonoperatingIncomeResidualSharingIncome | 10.8 gmt_NonoperatingIncomeResidualSharingIncome | 22.6 gmt_NonoperatingIncomeResidualSharingIncome
Non-remarketing disposition gains | 16.0 gmt_NonremarketingDispositionGainLoss | 20.7 gmt_NonremarketingDispositionGainLoss | 19.2 gmt_NonremarketingDispositionGainLoss
Asset impairments | (1.3)us-gaap_AssetImpairmentCharges | (5.9)us-gaap_AssetImpairmentCharges | (5.0)us-gaap_AssetImpairmentCharges
Net Gain on Asset Dispositions | $ 87.2 us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges | $ 85.6 us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges | $ 79.5 us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges

X
- Definition Nonoperating Income, Residual Sharing Income + References No definition available. + Details
Name: | gmt_NonoperatingIncomeResidualSharingIncome
Namespace Prefix: | gmt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Nonremarketing Disposition Gain (Loss) + References No definition available. + Details
Name: | gmt_NonremarketingDispositionGainLoss
Namespace Prefix: | gmt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: 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=8077374&loc=d3e2420-110228 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold or retired, and gain (loss) from the write down of assets from their carrying value to fair value. + References No definition available. + Details
Name: | us-gaap_GainLossOnSalesOfAssetsAndAssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) on sale or disposal of assets utilized in financial service operations. + References No definition available. + Details
Name: | us-gaap_GainsLossesOnSalesOfAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_SignificantAcquisitionsAndDisposalsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration