GATX (GATX) 10-Q 30 Oct 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	30-Sep-13
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3
Trading Symbol	GMT
Entity Registrant Name	GATX Corporation
Entity Central Index Key	40211
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	46.2

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, except Share data, unless otherwise specified
Assets
Cash and Cash Equivalents	$150.70	$234.20
Restricted Cash	21.8	29.7
Receivables
Rent and other receivables	81.1	88.4
Loans	120.3	27.2
Finance leases	213.7	245.7
Less: allowance for losses	-4.7	-4.6
Receivables, net	410.4	356.7
Operating Assets and Facilities
Operating Assets and Facilities ($123.2 and $123.1 related to a consolidated VIE)	7,400.60	6,855.20
Less: allowance for depreciation ($28.8 and $24.7 related to a consolidated VIE)	-2,291.90	-2,200.80
Operating assets and facilities, net	5,108.70	4,654.40
Investments in Affiliated Companies	361.9	502
Goodwill	93.5	91.7
Other Assets	192.1	186.7
Total Assets	6,339.10	6,055.40
Liabilities and Shareholders’ Equity
Accounts Payable and Accrued Expenses	197.5	177.4
Debt
Commercial paper and borrowings under bank credit facilities	47.5	273.6
Recourse	3,621.80	3,152.40
Nonrecourse ($27.9 and $35.1 related to a consolidated VIE)	75.2	130.6
Capital lease obligations	9	11.3
Total Debt	3,753.50	3,567.90
Deferred Income Taxes	839.5	783
Other Liabilities	236.5	282.9
Total Liabilities	5,027	4,811.20
Shareholders’ Equity
Preferred stock, Series A &B $2.50 Cumulative Convertible, $1.00 par value: Authorized shares — 5,000,000 Issued and outstanding shares — 0 and 15,567 Aggregate liquidation preference — $0 and $0.9 million			[1]
Common stock, $0.625 par value: Authorized shares — 120,000,000 Issued shares — 66,342,078 and 66,021,444 Outstanding shares — 46,223,958 and 46,898,924	41.3	41.2
Additional paid-in capital	663.7	658.5
Retained earnings	1,320	1,249.40
Accumulated other comprehensive loss	-102.6	-144.6
Treasury stock, at cost (shares — 20,118,120 and 19,122,520)	-610.3	-560.3
Total Shareholders’ Equity	1,312.10	1,244.20
Total Liabilities and Shareholders’ Equity	$6,339.10	$6,055.40
Series A and Series B preferred Stock [Member]
Debt
Preferred Stock, Shares Issued	0	15,567
[1]	Less than $0.1 million.

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Common stock, par value	$0.63	$0.63
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	66,342,078	66,021,444
Common stock, shares outstanding	46,223,958	46,898,924
Treasury stock, shares outstanding	20,118,120	19,122,520
VIE operating assets and facilities	$7,400,600,000	$6,855,200,000
VIE depreciation allowance	-2,291,900,000	-2,200,800,000
VIE nonrecourse debt	75,200,000	130,600,000
Variable Interest Entity, Primary Beneficiary [Member]
VIE operating assets and facilities	123,200,000	123,100,000
VIE depreciation allowance	-28,800,000	-24,700,000
VIE nonrecourse debt	27,900,000	35,100,000
Series A and B $2.50 Cumulative Convertible Preferred Stock [Member]
Preferred stock, par value	$1	$1
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	15,567
Preferred stock, shares outstanding	0	15,567
Preferred stock, aggregate liquidation preference	$0	$0.90
Cumulative annual cash dividend per share on preferred stock	$2.50	$2.50

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues
Lease revenue	$246.70	$231.50	$722.90	$682.60
Marine operating revenue	89	85.5	190.8	186.1
Other Revenue, Net	17.5	14.9	50.7	42.8
Total Revenues	353.2	331.9	964.4	911.5
Expenses
Maintenance expense	76.9	68.8	217.9	197.5
Marine operating expense	58.2	56.5	132.5	125.2
Depreciation expense	65.6	60.7	186.6	175.9
Operating lease expense	31.5	32.7	97.4	96.6
Other operating expense	6.9	6.6	19.2	16.6
Selling, general and administrative expense	42	38.6	129.8	115.6
Total Expenses	281.1	263.9	783.4	727.4
Other Income (Expense)
Net gain on asset dispositions	23.5	11.3	59.8	57.6
Interest expense, net	-41.1	-42.9	-125.2	-127.1
Other expense	-4.4	-3.9	-8.6	-4
Income before Income Taxes and Share of Affiliates’ Earnings	50.1	32.5	107	110.6
Income Taxes	-31.3	1.7	-47.9	-22.3
Share of Affiliates’ Earnings, Net of Tax	35	19.6	56.9	19.3
Net Income	53.8	53.8	116	107.6
Other Comprehensive Income, net of taxes
Foreign currency translation adjustments	32.9	10.8	13.4	8.7
Unrealized gain on securities	0.7	0	0.9	0.1
Unrealized gain on derivative instruments	15.4	0.2	21.3	13.6
Post-retirement benefit plans	2.1	1.4	6.4	4.1
Other Comprehensive Income	51.1	12.4	42	26.5
Comprehensive Income	$104.90	$66.20	$158	$134.10
Share Data
Basic earnings per share (in dollars per share)	$1.16	$1.15	$2.49	$2.30
Average number of common shares (in shares)	46.2	46.9	46.5	46.8
Diluted earnings per share (in dollars per share)	$1.15	$1.13	$2.45	$2.26
Average number of common shares and equivalents (in shares)	46.8	47.6	47.2	47.5
Dividends declared per common share (in dollars per share)	$0.31	$0.30	$0.93	$0.90

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2013
	USD ($)		USD ($)	Aae Cargo Ag [Member]		Aae Cargo Ag [Member]
	Vessel			USD ($)		EUR (€)
	Car
Operating Activities
Net income	$116		$107.60
Adjustments to reconcile income to net cash provided by operating activities:
Gains on sales of assets	-52.2		-52
Depreciation	196.1		184.9
Deferred income taxes	45.1		28.1
Share of affiliates’ earnings, net of dividends received	-44.9		-8.8
Increase (Decrease) in Income Taxes Payable	-1.8		-9.9
Change in accrued operating lease expense	-31.4		-36.6
Increase (Decrease) in Pension and Postretirement Obligations	6		0.5
Other	20.1		10.8
Net cash provided by operating activities	253		224.6
Investing Activities
Additions to operating assets and facilities	-551.3		-498.1
Loans extended	-14.2		-1
Investments in affiliates	-101.3		-24.3
Portfolio investments and capital additions	-666.8		-523.4
Purchases of leased-in assets	-58.5		-1.3
Portfolio proceeds	286.6		260.2	91.1	[1]	67.5	[1]
Proceeds from sales of other assets	24.4		22.5
Proceeds from sale-leasebacks			71.3
Net decrease in restricted cash	8		7.6
Net cash used in investing activities	-406.3		-163.1
Financing Activities
Net proceeds from issuances of debt (original maturities longer than 90 days)	801.8		312.9
Repayments of debt (original maturities longer than 90 days)	-405.7		-334.5
Net (decrease) increase in debt with original maturities of 90 days or less	-227.2		188.2
Repayments of Long-term Capital Lease Obligations	-2.3		-3
Stock repurchases	-50		0
Dividends	-46		-43.6
Other	0.8		1.5
Net cash provided by financing activities	71.4		121.5
Effect of Exchange Rate Changes on Cash and Cash Equivalents	-1.6		-0.8
Net (decrease) increase in Cash and Cash Equivalents	-83.5		182.2
Cash and Cash Equivalents, beginning of period	234.2		248.4
Cash and Cash Equivalents, end of period	150.7		430.6
Noncash or Part Noncash Acquisition, Value of Assets Acquired	$173	[2]
Number of vessels received	5
Number of railcars received	591
Noncontrolling Interest, Ownership Percentage by Parent				37.50%		37.50%
[1]	(b)In 2013, proceeds from the sale of our 37.5% interest in AAE included receipt of a note in the amount of $91.1 million.
[2]	(a)In 2013, we received five vessels and related working capital from our Singco and Somargas affiliates in connection with our exit from those joint ventures. Additionally, we received distributions of 591 railcars from our Southern Capital affiliate.

Description_of_Business

Description of Business	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	As used herein, "GATX," "we," "us," "our," and similar terms refer to GATX Corporation and its subsidiaries, unless indicated otherwise.
	We lease, operate, manage and remarket long-lived, widely-used assets, primarily in the rail and marine markets. We also invest in joint ventures that complement our existing business activities. We are headquartered in Chicago, Illinois, and have four primary business segments: Rail North America, Rail International, American Steamship Company (“ASC”) and Portfolio Management.

Basis_of_Presentation_Basis_of

Basis of Presentation Basis of Presentation	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation
	We prepared the accompanying unaudited consolidated financial statements in accordance with U.S. Generally Accepted Accounting Principles (“GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, our unaudited consolidated financial statements do not include all of the information and footnotes required for complete financial statements. We have included all of the normal recurring adjustments that we deemed necessary for a fair presentation.
	Our operating results for the nine months ended September 30, 2013, are not necessarily indicative of the results we may achieve for the entire year ending December 31, 2013. In particular, ASC’s fleet is inactive for a significant portion of the first quarter of each year due to winter conditions on the Great Lakes. In addition, asset remarketing income does not occur evenly throughout the year. For more information, refer to the consolidated financial statements and footnotes in our Annual Report on Form 10-K/A for the year ended December 31, 2012.
	Accounting Change
	Accumulated Other Comprehensive Income — In January 2013, the Financial Accounting Standards Board issued authoritative accounting guidance that requires presentation and disclosure of the effects on components of net income of significant amounts reclassified out of accumulated other comprehensive income. The guidance is effective for periods beginning after December 31, 2012. Application of the new guidance did not impact our financial position, results of operations, or cash flows. See "Note 5. Fair Value Disclosure," "Note 6. Pension and Other Post-Retirement Benefits," and "Note 11. Accumulated Other Comprehensive Income (Loss)" for the applicable disclosures.

Investments_in_Affliliated_Com

Investments in Affliliated Companies	9 Months Ended
	Sep. 30, 2013
Investments in and Advances to Affiliates, Schedule of Investments [Abstract]
Investments in and Advances to Affiliates, Schedule of Investments [Text Block]	Investments in Affiliated Companies
	Investments in affiliated companies represent investments in and loans to domestic and foreign affiliates that are in businesses similar to those of GATX, primarily companies offering lease financing and related services for customers operating rail and marine assets, as well as companies that lease aircraft engines.
	In the third quarter of 2013, we sold our 37.5% interest in AAE Ahaus Alstätter Eisenbahn Cargo AG (“AAE”) to our partner, AAE Ahaus Alstätter Eisenbahn Holding AG (“AAE Holding”) and recognized a pre-tax gain of $9.3 million, which is reported as part of share of affiliates' earnings. The sale price of €84.5 million ($114.1 million) consisted of a cash payment at closing of €17.0 million ($23.0 million) and a seller loan in the amount of €67.5 million ($91.1 million) at a market interest rate. The loan has an initial term of one year, with two six-month extensions at AAE Holding's option. If AAE Holding exercises one or both of its extension options, the interest rate will adjust to a higher rate for the extension period. The loan is secured by a pledge of all AAE shares sold by us to AAE Holding. The loan agreement also contains customary affirmative and negative covenants, including financial covenants related to AAE's tangible net worth, leverage and interest cover. At its option, AAE Holding may prepay the loan, in whole or in part, at any time, and AAE Holding has informed us that they are working on various financing alternatives to repay the loan prior to maturity. As a result of this sale, we are now better positioned to independently pursue growth opportunities in the European rail market through our wholly-owned business, GATX Rail Europe.

Variable_Interest_Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2013
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Variable Interest Entities	Variable Interest Entities
	We evaluate whether an entity is a variable interest entity (“VIE”) based on the sufficiency of the entity’s equity and determining whether the equity holders have the characteristics of a controlling financial interest. We assess whether we are the primary beneficiary of a VIE based on our ability to direct the activities that most significantly impact the economic performance of the VIE and our obligation to absorb losses or our right to receive benefits that may be significant to the VIE. These determinations are both qualitative and quantitative, and they require us to make judgments and assumptions about the VIE’s forecasted financial performance and the volatility inherent in those forecasts. We evaluate new investments for VIE classification, and we regularly review all existing entities for events that may result in an entity becoming a VIE or us becoming a primary beneficiary.
	We determined that we are the primary beneficiary of one of our VIEs, a structured lease financing for a portfolio of railcars, because we have the authority to direct its significant activities. We consolidate this VIE and the risks associated with it are similar to those of our wholly-owned railcar leasing activities.
	The following table shows the carrying amounts of our consolidated VIE's assets and liabilities (in millions):
		September 30 2013		December 31
				2012
	Operating assets, net of accumulated depreciation (a)	$	94.4	$	98.4
	Nonrecourse debt	27.9		35.1
	________________
	(a) All operating assets are pledged as collateral on the nonrecourse debt.
	We determined that we are not the primary beneficiary of our other VIEs, primarily investments in railcar and equipment leasing affiliates that were financed through a variety of equity investments and third party lending arrangements. We are not the primary beneficiary of these VIEs because we do not have the power to direct the activities that most significantly impact the entities’ economic performance. For the investments in affiliates that we determined are VIEs, we concluded that power was shared by the affiliate partners based on the terms of the relevant joint venture agreements, which require approval of all partners for significant decisions involving the VIE.
	The following table shows the carrying amounts and maximum exposure to loss for our VIEs that we do not consolidate (in millions):
		30-Sep-13				December 31, 2012
		Net		Maximum		Net		Maximum
		Carrying		Exposure		Carrying		Exposure
		Amount		to Loss		Amount		to Loss
	Investments in affiliates	$	135.7	$	135.7	$	110.7	$	110.7
	Other investment	0.6		0.6		0.7		0.7
	Total	$	136.3	$	136.3	$	111.4	$	111.4

Fair_Value_Disclosure

Fair Value Disclosure	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]
Fair Value Disclosure	Fair Value Disclosure
	The following tables show our assets and liabilities that are measured at fair value on a recurring basis (in millions):
		30-Sep			Quoted Prices in			Significant			Significant
		2013			Active Markets			Observable			Unobservable
					for Identical			Inputs			Inputs
					Assets			(Level 2)			(Level 3)
					(Level 1)
	Assets
	Interest rate derivatives (a)	$	7.4		$	—		$	7.4		$	—
	Available-for-sale equity securities	4.8			4.8			—			—
	Liabilities
	Interest rate derivatives (a)	0.2			—			0.2			—
	Interest rate derivatives (b)	0.2			—			0.2			—
	Foreign exchange rate derivatives (b)	1.4			—			1.4			—
		December 31 2012			Quoted Prices in			Significant			Significant
					Active Markets			Observable			Unobservable
					for Identical			Inputs			Inputs
					Assets			(Level 2)			(Level 3)
					(Level 1)
	Assets
	Interest rate derivatives (a)	$	10.2		$	—		$	10.2		$	—
	Available-for-sale equity securities	3.3			3.3			—			—
	Liabilities
	Interest rate derivatives (a)	1			—			1			—
	Interest rate derivatives (b)	0.3			—			0.3			—
	Foreign exchange rate derivatives (b)	2.1			—			2.1			—
	________________
	(a)	Designated as hedges
	(b)	Not designated as hedges
	We base our valuations of available-for-sale equity securities on their quoted prices on an active exchange. We value derivatives using a pricing model with inputs (such as yield curves and credit spreads) that are observable in the market or that can be derived principally from observable market data.
	Derivative instruments
	Fair Value Hedges — We use interest rate swaps to manage the fixed-to-floating rate mix of our debt obligations by converting fixed rate debt to floating rate debt. For fair value hedges, we recognize changes in the fair value of both the derivative and the hedged item as interest expense. As of September 30, 2013, we had two instruments outstanding with an aggregate notional amount of $150.0 million, one of which matures in 2015 and the other in 2018. As of December 31, 2012, we had one instrument outstanding with an notional amount of $100.0 million.
	Cash Flow Hedges — We use interest rate swaps to convert floating rate debt to fixed rate debt. We also use Treasury rate locks to hedge our exposure to interest rate risk on anticipated transactions. We had 5 instruments outstanding with an aggregate notional amount of $133.9 million as of September 30, 2013, with maturities ranging from 2014 to 2020. As of December 31, 2012, we had12 instruments outstanding with an aggregate notional amount of $129.2 million. Within the next 12 months, we expect to reclassify $6.3 million ($4.0 million after-tax) of net losses on previously terminated derivatives from accumulated other comprehensive loss. We reclassify these amounts when interest and operating lease expense on the related hedged transactions affect earnings.
	Non-designated Derivatives — We do not hold derivative financial instruments for purposes other than hedging, although certain of our derivatives are not designated as accounting hedges. We recognize changes in the fair value of these derivatives in other (income) expense immediately.
	Some of our derivative instruments contain credit risk provisions that require us to make immediate payment on net liability positions in the event we default on certain outstanding debt obligations. The aggregate fair value of our derivative instruments with credit risk related contingent features that are in a liability position as of September 30, 2013, was $0.4 million. We are not required to post collateral on our derivative instruments and do not expect the credit risk provisions to be triggered.
	In the event that a counterparty fails to meet the terms of an active derivative contract, our exposure is limited to the fair value of the derivative, if in our favor. We manage the credit risk of counterparties by transacting with institutions that we consider financially sound and by avoiding concentrations of risk with a single counterparty. We believe that the risk of non-performance by any of our counterparties is remote.
	The following table shows the impacts of our derivative instruments on our statement of comprehensive income (in millions):
	Derivative		Location of Gain (Loss) Recognized	Three Months Ended September 30						Nine Months Ended September 30
	Designation			2013			2012			2013			2012
	Fair value hedges (a)		Interest expense	$	(0.8	)	$	(1.3	)	$	(3.1	)	$	(3.9	)
	Cash flow hedges		Unrealized (loss) gain on derivative instruments (effective portion)	(0.1		)	0.3			0.8			1
	Cash flow hedges		Interest expense (effective portion reclassified from accumulated other comprehensive loss)	(1.3		)	(1.1		)	(3.8		)	(4.1		)
	Cash flow hedges		Operating lease expense (effective portion reclassified from accumulated other comprehensive loss)	(0.4		)	(0.4		)	(1.1		)	(1.1		)
	Non-designated		Other (expense) income	(1.7		)	(2.1		)	0.6			(0.6		)
	__________________
	(a)	The fair value adjustments related to the underlying debt equally offsets the amounts recognized in interest expense.
	Other Financial Instruments
	The carrying amounts of our cash and cash equivalents, restricted cash, rent and other receivables, accounts payable, commercial paper, and bank credit facilities approximate fair value due to the short maturity of those instruments. We base the fair values of investment funds, which are accounted for under the cost method, on the best information available, which may include quoted investment fund values. We estimate the fair values of loans, and fixed and floating rate debt using discounted cash flow analyses based on interest rates currently offered for loans with similar terms to borrowers of similar credit quality. The inputs we use to estimate each of these fair values are classified in Level 2 of the fair value hierarchy because they are directly or indirectly observable inputs.
	The following table shows the carrying amounts and fair values of our other financial instruments as of (in millions):
		30-Sep-13						December 31, 2012
		Carrying			Fair			Carrying			Fair
		Amount			Value			Amount			Value
	Assets
	Investment funds	$	1.7		$	5.3		$	2.5		$	5.8
	Loans	120.3			120.6			27.2			27.7
	Liabilities
	Recourse fixed rate debt	$	2,684.80		$	2,794.60		$	2,343.30		$	2,513.40
	Recourse floating rate debt	937			947.2			809.1			807.9
	Nonrecourse debt	75.2			77.7			130.6			138.2

Pension_and_Other_PostRetireme

Pension and Other Post-Retirement Benefits	9 Months Ended
	Sep. 30, 2013
Compensation and Retirement Disclosure [Abstract]
Pension and Other Post-Retirement Benefits	Pension and Other Post-Retirement Benefits
	The following table shows the components of our pension and other post-retirement benefit expense for the three months ended September 30, 2013 and 2012 (in millions):
		2013 Pension			2012 Pension			2013 Retiree			2012 Retiree
		Benefits			Benefits			Health and			Health and
								Life			Life
	Service cost	$	1.7		$	1.5		$	0.1		$	0.1
	Interest cost	4.6			4.9			0.4			0.5
	Expected return on plan assets	(6.9		)	(7.4		)	—			—
	Amortization of (a):
	Unrecognized prior service credit	(0.3		)	(0.3		)	—			—
	Unrecognized net actuarial loss	3.7			2.5			—			—
	Net expense	$	2.8		$	1.2		$	0.5		$	0.6
	The following table shows the components of our pension and other post-retirement benefit expense for the nine months ended September 30, 2013 and 2012 (in millions):
		2013 Pension			2012 Pension			2013 Retiree			2012 Retiree
		Benefits			Benefits			Health and			Health and
								Life			Life
	Service cost	$	5.1		$	4.5		$	0.2		$	0.2
	Interest cost	13.8			14.8			1.2			1.5
	Expected return on plan assets	(20.7		)	(22.2		)	—			—
	Amortization of (a):
	Unrecognized prior service credit	(0.8		)	(0.8		)	(0.1		)	(0.1		)
	Unrecognized net actuarial loss (gain)	11.2			7.5			—			(0.1		)
	Net expense	$	8.6		$	3.8		$	1.3		$	1.5
	________________
	(a)	Amounts are reclassified from accumulated other comprehensive loss.

ShareBased_Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation
	During the first nine months of 2013, we granted 317,100 stock appreciation rights (“SARs”), 67,970 restricted stock units, 68,780 performance shares, and 15,401 phantom stock units. For the three and nine months ended September 30, 2013, total share-based compensation expense was $3.1 million and $9.5 million and the related tax benefits were $1.2 million and $3.6 million. For the three and nine months ended September 30, 2012, total share-based compensation expense was $3.0 million and $9.1 million and the related tax benefits were $1.1 million and $3.4 million, respectively.
	The weighted average estimated fair value of our 2013 SARs awards and our related underlying assumptions are shown in the table below.
		2013
	Weighted average estimated fair value	$	18.89
	Quarterly dividend rate	$	0.3
	Expected term of SARs, in years	4.7
	Risk-free interest rate	0.7		%
	Dividend yield	2.6		%
	Expected stock price volatility	42.4		%
	Present value of dividends	$	5.6

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	Our effective tax rate was 45% for the nine months ended September 30, 2013 compared to 20% for the nine months ended September 30, 2012. The current year effective tax rate reflects U.S. and state income taxes of $23.2 million incurred by GATX on the tax gain recognized on the sale of our investment in AAE. Additionally, foreign tax credit carry forwards of $3.9 million were recognized as a result of this gain. In the prior year, GATX’s liability for unrecognized tax benefits was reduced by $15.5 million in connection with the close of a federal tax audit. Excluding the effects of the AAE gain and other tax benefits from each year as applicable, GATX’s effective tax rate for the first nine months of 2013 and 2012 was 27% and 34%, respectively. The remaining difference in the effective tax rates for each year is primarily attributable to the mix of pre-tax income among domestic and foreign jurisdictions which are taxed at different rates.
	As of September 30, 2013, our gross liability for unrecognized tax benefits was $4.7 million. If fully recognized, these tax benefits would decrease our income tax expense by $4.7 million ($3.2 million, net of federal tax). Subject to the completion of certain audits or the expiration of the applicable statute of limitations, we believe it is reasonably possible that we will recognize $0.4 million in unrecognized tax benefits within the next 12 months.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share
	We compute basic earnings per share by dividing our net income available to our common shareholders by the weighted average number of shares of our common stock outstanding. Shares issued or reacquired during the period were appropriately weighted for the portion of the period that they were outstanding. Our diluted earnings per share reflect the impacts of our potentially dilutive securities, which include our convertible preferred stock and our equity compensation awards.
	In the second quarter of 2013, both series of our preferred stock were retired with all shares either converted to common stock or redeemed.
	The following table shows the computation of our basic and diluted net income per common share (in millions, except per share amounts):
		Three Months Ended September 30				Nine Months Ended September 30
		2013		2012		2013		2012
	Numerator:
	Net income	$	53.8	$	53.8	$	116	$	107.6
	Denominator:
	Weighted average shares outstanding - basic	46.2		46.9		46.5		46.8
	Effect of dilutive securities:
	Equity compensation plans	0.6		0.6		0.7		0.6
	Convertible preferred stock	*		0.1		*		0.1
	Weighted average shares outstanding - diluted	46.8		47.6		47.2		47.5
	Basic earnings per share	$	1.16	$	1.15	$	2.49	$	2.3
	Diluted earnings per share	$	1.15	$	1.13	$	2.45	$	2.26
	_______________
	* Antidilutive

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss)
	The following table shows the changes in the components of our accumulated other comprehensive income (loss) (in millions):
		Foreign			Unrealized			Unrealized Loss on Derivative Instruments			Post- RetirementBenefit Plans			Total
		Currency			Gain (Loss) on Securities
		Translation
		Gain (Loss)
	Balance at December 31, 2012	$	31.4		$	(0.4	)	$	(44.5	)	$	(131.1	)	$	(144.6	)
	Change in component	(17.0		)	0.2			0.6			—			(16.2		)
	Reclassification adjustments into earnings	—			—			1.6			3.3			4.9
	Income tax effect	—			(0.1		)	(0.7		)	(1.3		)	(2.1		)
	Balance at March 31, 2013	14.4			(0.3		)	(43.0		)	(129.1		)	(158.0		)
	Change in component	(2.5		)	0.1			4.3			—			1.9
	Reclassification adjustments into earnings	—			—			1.6			3.6			5.2
	Income tax effect	—			—			(1.5		)	(1.3		)	(2.8		)
	Balance at June 30, 2013	11.9			(0.2		)	(38.6		)	(126.8		)	(153.7		)
	Change in component	32.9			1.1			18			—			52
	Reclassification adjustments into earnings	—			—			1.7			3.4			5.1
	Income tax effect	—			(0.4		)	(4.3		)	(1.3		)	(6.0		)
	Balance at September 30, 2013	$	44.8		$	0.5		$	(23.2	)	$	(124.7	)	$	(102.6	)
	______________
	See "Note 5. Fair Value Disclosure" and "Note 6. Pension and Other Post-Retirement Benefits" for the effects of the reclassification adjustments on the statement of comprehensive income.

Legal_Proceedings_and_Other_Co

Legal Proceedings and Other Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]
Legal Proceedings and Other Contingencies	Legal Proceedings and Other Contingencies
	Various legal actions, claims, assessments, and other contingencies arise in the ordinary course of our business and are pending against us. Legal matters are subject to numerous uncertainties and they may be resolved adversely. For a full discussion of our material pending legal matters, please refer to "Note 22. Legal Proceedings and Other Contingencies" of our consolidated financial statements in our Annual Report on Form 10-K/A for the year ended December 31, 2012. Except as noted below, there have been no material changes in our legal matters.
	Viareggio Derailment
	In June 2009, a train consisting of fourteen liquefied petroleum gas (“LPG”) tank cars owned by GATX Rail Austria GmbH (an indirect subsidiary of the Company, "GATX Rail Austria") and its subsidiaries derailed while passing through Viareggio, Italy. Five tank cars overturned and one of the overturned cars was punctured by a peg or obstacle along the side of the track, resulting in a release of LPG, which subsequently ignited. Thirty-two people died and others were injured in the fire, which also resulted in property damage. The LPG tank cars were leased to FS Logistica S.p.A., a subsidiary of the Italian state-owned railway, Ferrovie dello Stato S.p.A (the “Italian Railway”).
	On December 14, 2012, the Public Prosecutors of Lucca ("Public Prosecutors") formally charged GATX Rail Austria and two of its subsidiaries (collectively, "GRA"), as well as several maintenance and supervisory employees (the "Employees"), with various negligence-based crimes related to the accident, all of which are punishable under Italian law by incarceration, damages and fines. Similar charges were brought against four Italian Railway companies and eighteen of their employees, among others. During a preliminary hearing before the Court of Lucca, the Public Prosecutors argued that one of the tank car’s axles broke causing the derailment and resulted in a tank car rupture and release of LPG, after the car hit an obstacle placed on the side of the track by the Italian Railway. The Public Prosecutors further alleged that a crack in the axle was detectable at the time of final inspection but was overlooked by the Employees at the Jungenthal Waggon GmbH workshop (a subsidiary of GATX Rail Austria). On July 17, 2013, the Court of Lucca committed all defendants to trial, (the “Lucca Trial”), which will begin on November 13, 2013. With respect to civil claimants, GRA’s insurers continue to work cooperatively with the insurer for the Italian Railway to adjust and settle personal injury and property damage claims. These joint settlement efforts have so far settled the majority of asserted civil damage claims related to the accident, but approximately 110 civil claimants, who have not settled their claims, have joined as parties to the Lucca Trial, and the court will determine both the civil and criminal liability of the defendants in the one proceeding.
	The Company believes that GRA and its Employees acted diligently and properly with respect to applicable legal and industry standards and will present numerous scientific and technical defenses to the Public Prosecutors' charges and civil claimants’ claims at the Lucca Trial. Since May 2012, the excess insurer providing coverage at the current layer, Liberty Mutual Insurance Europe Limited (“Liberty”), while settling civil claims, has refused to reimburse GRA for its ongoing legal defense fees and costs, taking a position contrary to insurers in the prior underlying layers who had provided coverage for such expenses. To date, GRA has incurred approximately $4.0 million of unreimbursed defense fees and costs in the current coverage layer and continues to incur costs in connection with the Lucca Trial. Consequently, GRA recently filed an arbitration proceeding against Liberty seeking to recoup its defense fees and costs. The Company currently is not in a position to predict the outcome of this arbitration, the amount of defense fees and costs that ultimately may not be reimbursed by Liberty, when Liberty’s layer will fully exhaust, and the position other excess insurers may take in the future regarding reimbursement of legal defense fees and costs. Notwithstanding Liberty’s refusal to reimburse GRA for defense fees and costs, GRA’s insurance carriers, including Liberty, have continued to cover civil claims arising from the accident, and the Company expects that they will continue to do so, including any civil damage awards.
	The Company cannot predict the outcome of the Lucca Trial or what other legal proceedings, if any, may be initiated against GRA or its personnel, and, therefore, cannot reasonably estimate the amount or range of loss that may ultimately be incurred in connection with this accident. Accordingly, the Company has not established any accruals with respect to this matter.

Financial_Data_of_Business_Seg

Financial Data of Business Segments	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]
Financial Data of Business Segments	We lease, operate, manage, and remarket long-lived, widely-used assets, primarily in the rail and marine markets. We also invest in joint ventures that complement our existing business activities. We have four primary business segments: Rail North America, Rail International, American Steamship Company (“ASC”), and Portfolio Management.
	Rail North America is comprised of our wholly-owned operations in the United States, Canada, and Mexico, as well as two affiliate investments. Rail North America primarily leases railcars to customers on full-service leases, which require us to maintain the railcars, pay ad valorem taxes and insurance, and provide other ancillary services.
	Rail International is comprised of our wholly-owned European rail operations ("Rail Europe") and our newly-established railcar leasing business in India ("Rail India"), as well as one affiliate investment. Rail Europe leases railcars, predominantly tank cars, to customers throughout Europe on full-service leases, which require us to maintain the railcars and provide insurance and other ancillary services.
	ASC operates the largest fleet of U.S. flagged vessels on the Great Lakes, providing waterborne transportation of dry bulk commodities such as iron ore, coal, limestone aggregates, and metallurgical limestone.
	Portfolio Management is an aggregation of a group of diversified owned assets and joint venture investments ("affiliates"), and provides leasing, asset remarketing, and asset management services. Portfolio Management selectively invests in long-lived, widely-used assets with a focus on domestic marine and container related equipment, and extends our market reach through affiliate investments.
	Segment profit is an internal performance measure our Chief Executive Officer uses to assess the performance of each segment in a given period. Segment profit includes all revenues, pre-tax earnings from affiliates, and net gains on asset dispositions that are attributable to the segments as well as expenses that we believe are directly associated with the financing, maintenance, and operation of our revenue-earning assets. Segment profit excludes selling, general and administrative expenses, income taxes, and other unallocated amounts.
	We allocate debt and interest expense to each segment based upon a predetermined fixed recourse leverage level expressed as a ratio of recourse debt (including off-balance-sheet debt) to equity. The leverage levels are 5:1 for Rail North America, 2:1 for Rail International, 1.5:1 for ASC, and 3:1 for Portfolio Management. We believe that by utilizing this allocation methodology, each segment’s financial performance reflects appropriate risk-adjusted borrowing costs.
	The following tables show the profitability, financial position, and investment volume of each of our business segments (in millions):
		Rail North America			Rail International			ASC			Portfolio Management			Other			GATX Consolidated
	Three Months Ended September 30, 2013
	Profitability
	Revenues
	Lease revenue	$	192.2		$	45.6		$	1.1		$	7.8		$	—		$	246.7
	Marine operating revenue	—			—			73			16			—			89
	Other revenue	14.3			1.9			—			1.3			—			17.5
	Total Revenues	206.5			47.5			74.1			25.1			—			353.2
	Expenses
	Maintenance expense	58.6			10.9			7.4			—			—			76.9
	Marine operating expense	—			—			47.2			11			—			58.2
	Depreciation expense	44.9			10.8			4.1			5.8			—			65.6
	Operating lease expense	29.7			—			1.8			—			—			31.5
	Other operating expense	4.9			1.3			—			0.7			—			6.9
	Total Expenses	138.1			23			60.5			17.5			—			239.1
	Other Income (Expense)
	Net gain on asset dispositions	20.5			1.3			—			1.7			—			23.5
	Interest expense, net	(26.1		)	(6.7		)	(1.6		)	(6.3		)	(0.4		)	(41.1		)
	Other (expense) income	(4.8		)	(1.0		)	0.9			—			0.5			(4.4		)
	Share of affiliates' earnings (pre-tax)	(0.1		)	16.7			—			14.7			—			31.3
	Segment Profit	$	57.9		$	34.8		$	12.9		$	17.7		$	0.1		123.4
	Selling, general and administrative expense																42
	Income taxes (includes $3.7 of net tax benefits related to affiliates' earnings)																27.6
	Net Income																$	53.8
	Investment Volume
	Portfolio investments and capital additions	$	130.8		$	43.7		$	—		$	19.3		$	2.4		$	196.2
	Selected Balance Sheet Data at September 30, 2013
	Investments in affiliated companies	$	31.5		$	2.1		$	—		$	328.3		$	—		$	361.9
	Identifiable assets	$	3,781.60		$	1,269.60		$	285.5		$	851.5		$	150.9		$	6,339.10
		Rail North America			Rail International			ASC			Portfolio Management			Other			GATX Consolidated
	Three Months Ended September 30, 2012
	Profitability
	Revenues
	Lease revenue	$	180.7		$	40.1		$	1.1		$	9.6		$	—		$	231.5
	Marine operating revenue	—			—			79.1			6.4			—			85.5
	Other revenue	12.7			1.4			—			0.8			—			14.9
	Total Revenues	193.4			41.5			80.2			16.8			—			331.9
	Expenses
	Maintenance expense	51.3			9.8			7.7			—			—			68.8
	Marine operating expense	—			—			51.3			5.2			—			56.5
	Depreciation expense	42.2			8.9			4			5.6			—			60.7
	Operating lease expense	31.4			—			1.3			—			—			32.7
	Other operating expense	5.2			1.1			—			0.3			—			6.6
	Total Expenses	130.1			19.8			64.3			11.1			—			225.3
	Other Income (Expense)
	Net gain on asset dispositions	9.2			1			—			1.1			—			11.3
	Interest expense, net	(26.3		)	(6.1		)	(1.8		)	(6.9		)	(1.8		)	(42.9		)
	Other (expense) income	(1.8		)	(1.8		)	(0.9		)	0.3			0.3			(3.9		)
	Share of affiliates' earnings (pre-tax)	1.2			3.1			—			14.8			—			19.1
	Segment Profit (Loss)	$	45.6		$	17.9		$	13.2		$	15		$	(1.5	)	90.2
	Selling, general and administrative expense																38.6
	Income taxes (includes $0.5 of net tax benefits related to affiliates' earnings)																(2.2		)
	Net Income																$	53.8
	Investment Volume
	Portfolio investments and capital additions	$	81.9		$	41.4		$	0.3		$	6.3		$	1.7		$	131.6
	Selected Balance Sheet Data at December 31, 2012
Investments in affiliated companies	$	46.9		$	77.2		$	—		$	377.9		$	—		$	502
Identifiable assets	$	3,601.10		$	1,105.80		$	284.2		$	797.4		$	266.9		$	6,055.40
	Rail North America			Rail International			ASC			Portfolio Management			Other			GATX Consolidated
Nine Months Ended September 30, 2013
Profitability
Revenues
Lease revenue	$	563.3		$	132.2		$	3.2		$	24.2		$	—		$	722.9
Marine operating revenue	—			—			157			33.8			—			190.8
Other revenue	41.9			5.8			—			3			—			50.7
Total Revenues	605.2			138			160.2			61			—			964.4
Expenses
Maintenance expense	170.8			32			15.1			—			—			217.9
Marine operating expense	—			—			105.2			27.3			—			132.5
Depreciation expense	129.9			31.5			8.1			17.1			—			186.6
Operating lease expense	94			—			3.5			—			(0.1		)	97.4
Other operating expense	13.9			3.6			—			1.7			—			19.2
Total Expenses	408.6			67.1			131.9			46.1			(0.1		)	653.6
Other Income (Expense)
Net gain on asset dispositions	40.9			3.8			—			15.1			—			59.8
Interest expense, net	(80.5		)	(17.5		)	(4.8		)	(19.7		)	(2.7		)	(125.2		)
Other (expense) income	(8.9		)	(0.5		)	0.3			—			0.5			(8.6		)
Share of affiliates' earnings (pre-tax)	8.3			21.1			—			37.2			—			66.6
Segment Profit (Loss)	$	156.4		$	77.8		$	23.8		$	47.5		$	(2.1	)	303.4
Selling, general and administrative expense																129.8
Income taxes (includes $9.7 related to affiliates' earnings)																57.6
Net Income																$	116
Investment Volume
Portfolio investments and capital additions	$	345.9		$	134.9		$	11		$	170.5		$	4.5		$	666.8
	Rail North America			Rail International			ASC			Portfolio Management			Other			GATX Consolidated
Nine Months Ended September 30, 2012
Profitability
Revenues
Lease revenue	$	531.9		$	119.1		$	3.2		$	28.4		$	—		$	682.6
Marine operating revenue	—			—			166			20.1			—			186.1
Other revenue	36.6			3.9			—			2.3			—			42.8
Total Revenues	568.5			123			169.2			50.8			—			911.5
Expenses
Maintenance expense	148.1			34.6			14.8			—			—			197.5
Marine operating expense	—			—			108.6			16.6			—			125.2
Depreciation expense	125.7			26.1			7.9			16.2			—			175.9
Operating lease expense	94.1			—			2.5			0.2			(0.2		)	96.6
Other operating expense	13.6			4			(0.3		)	(0.7		)	—			16.6
Total Expenses	381.5			64.7			133.5			32.3			(0.2		)	611.8
Other Income (Expense)
Net gain on asset dispositions	39.7			3.1			—			14.8			—			57.6
Interest expense, net	(78.0		)	(19.0		)	(5.5		)	(20.6		)	(4.0		)	(127.1		)
Other (expense) income	(3.9		)	(3.3		)	(0.9		)	3.4			0.7			(4.0		)
Share of affiliates' earnings (pre-tax)	4.7			(16.9		)	—			35.5			—			23.3
Segment Profit (Loss)	$	149.5		$	22.2		$	29.3		$	51.6		$	(3.1	)	249.5
Selling, general and administrative expense																115.6
Income taxes (includes $4.0 related to affiliates' earnings)																26.3
Net Income																$	107.6
Investment Volume
Portfolio investments and capital additions	$	318.5		$	125.4		$	11.7		$	62.8		$	5		$	523.4

Variable_Interest_Entities_Tab

Variable Interest Entities (Tables)	9 Months Ended
	Sep. 30, 2013
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Carrying amounts of assets and liabilities of consolidated VIE	The following table shows the carrying amounts of our consolidated VIE's assets and liabilities (in millions):
		September 30 2013		December 31
				2012
	Operating assets, net of accumulated depreciation (a)	$	94.4	$	98.4
	Nonrecourse debt	27.9		35.1
	________________
	(a) All operating assets are pledged as collateral on the nonrecourse debt.
Carrying amounts and maximum exposure to loss for non consolidated VIEs	The following table shows the carrying amounts and maximum exposure to loss for our VIEs that we do not consolidate (in millions):
		30-Sep-13				December 31, 2012
		Net		Maximum		Net		Maximum
		Carrying		Exposure		Carrying		Exposure
		Amount		to Loss		Amount		to Loss
	Investments in affiliates	$	135.7	$	135.7	$	110.7	$	110.7
	Other investment	0.6		0.6		0.7		0.7
	Total	$	136.3	$	136.3	$	111.4	$	111.4

Fair_Value_Disclosure_Tables

Fair Value Disclosure (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]
Assets and Liabilities at Fair Value, Recurring Basis	The following tables show our assets and liabilities that are measured at fair value on a recurring basis (in millions):
		30-Sep			Quoted Prices in			Significant			Significant
		2013			Active Markets			Observable			Unobservable
					for Identical			Inputs			Inputs
					Assets			(Level 2)			(Level 3)
					(Level 1)
	Assets
	Interest rate derivatives (a)	$	7.4		$	—		$	7.4		$	—
	Available-for-sale equity securities	4.8			4.8			—			—
	Liabilities
	Interest rate derivatives (a)	0.2			—			0.2			—
	Interest rate derivatives (b)	0.2			—			0.2			—
	Foreign exchange rate derivatives (b)	1.4			—			1.4			—
		December 31 2012			Quoted Prices in			Significant			Significant
					Active Markets			Observable			Unobservable
					for Identical			Inputs			Inputs
					Assets			(Level 2)			(Level 3)
					(Level 1)
	Assets
	Interest rate derivatives (a)	$	10.2		$	—		$	10.2		$	—
	Available-for-sale equity securities	3.3			3.3			—			—
	Liabilities
	Interest rate derivatives (a)	1			—			1			—
	Interest rate derivatives (b)	0.3			—			0.3			—
	Foreign exchange rate derivatives (b)	2.1			—			2.1			—
	________________
	(a)	Designated as hedges
	(b)	Not designated as hedges
Impact of GATX's Derivative Instrument On Income Statement and Other comprehensive income (loss)	The following table shows the impacts of our derivative instruments on our statement of comprehensive income (in millions):
	Derivative		Location of Gain (Loss) Recognized	Three Months Ended September 30						Nine Months Ended September 30
	Designation			2013			2012			2013			2012
	Fair value hedges (a)		Interest expense	$	(0.8	)	$	(1.3	)	$	(3.1	)	$	(3.9	)
	Cash flow hedges		Unrealized (loss) gain on derivative instruments (effective portion)	(0.1		)	0.3			0.8			1
	Cash flow hedges		Interest expense (effective portion reclassified from accumulated other comprehensive loss)	(1.3		)	(1.1		)	(3.8		)	(4.1		)
	Cash flow hedges		Operating lease expense (effective portion reclassified from accumulated other comprehensive loss)	(0.4		)	(0.4		)	(1.1		)	(1.1		)
	Non-designated		Other (expense) income	(1.7		)	(2.1		)	0.6			(0.6		)
	__________________
	(a)	The fair value adjustments related to the underlying debt equally offsets the amounts recognized in interest expense
Fair Value Other Financial Instruments	The following table shows the carrying amounts and fair values of our other financial instruments as of (in millions):
		30-Sep-13						December 31, 2012
		Carrying			Fair			Carrying			Fair
		Amount			Value			Amount			Value
	Assets
	Investment funds	$	1.7		$	5.3		$	2.5		$	5.8
	Loans	120.3			120.6			27.2			27.7
	Liabilities
	Recourse fixed rate debt	$	2,684.80		$	2,794.60		$	2,343.30		$	2,513.40
	Recourse floating rate debt	937			947.2			809.1			807.9
	Nonrecourse debt	75.2			77.7			130.6			138.2

Pension_and_Other_PostRetireme1

Pension and Other Post-Retirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2013
Compensation and Retirement Disclosure [Abstract]
Components of pension and other post retirement benefit costs	The following table shows the components of our pension and other post-retirement benefit expense for the three months ended September 30, 2013 and 2012 (in millions):
		2013 Pension			2012 Pension			2013 Retiree		2012 Retiree
		Benefits			Benefits			Health and		Health and
								Life		Life
	Service cost	$	1.7		$	1.5		$	0.1	$	0.1
	Interest cost	4.6			4.9			0.4		0.5
	Expected return on plan assets	(6.9		)	(7.4		)	—		—
	Amortization of (a):
	Unrecognized prior service credit	(0.3		)	(0.3		)	—		—
	Unrecognized net actuarial loss	3.7			2.5			—		—
	Net expense	$	2.8		$	1.2		$	0.5	$	0.6

Share_Based_Compensation_Table

Share Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted Average Estimated Fair Value [Table Text Block]	The weighted average estimated fair value of our 2013 SARs awards and our related underlying assumptions are shown in the table below.
		2013
	Weighted average estimated fair value	$	18.89
	Quarterly dividend rate	$	0.3
	Expected term of SARs, in years	4.7
	Risk-free interest rate	0.7		%
	Dividend yield	2.6		%
	Expected stock price volatility	42.4		%
	Present value of dividends	$	5.6

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]
Computation of basic and diluted net income per common share	The following table shows the computation of our basic and diluted net income per common share (in millions, except per share amounts):
		Three Months Ended September 30				Nine Months Ended September 30
		2013		2012		2013		2012
	Numerator:
	Net income	$	53.8	$	53.8	$	116	$	107.6
	Denominator:
	Weighted average shares outstanding - basic	46.2		46.9		46.5		46.8
	Effect of dilutive securities:
	Equity compensation plans	0.6		0.6		0.7		0.6
	Convertible preferred stock	*		0.1		*		0.1
	Weighted average shares outstanding - diluted	46.8		47.6		47.2		47.5
	Basic earnings per share	$	1.16	$	1.15	$	2.49	$	2.3
	Diluted earnings per share	$	1.15	$	1.13	$	2.45	$	2.26

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]
Accumulated other comprehensive income (loss)	The following table shows the changes in the components of our accumulated other comprehensive income (loss) (in millions):
		Foreign			Unrealized			Unrealized Loss on Derivative Instruments			Post- RetirementBenefit Plans			Total
		Currency			Gain (Loss) on Securities
		Translation
		Gain (Loss)
	Balance at December 31, 2012	$	31.4		$	(0.4	)	$	(44.5	)	$	(131.1	)	$	(144.6	)
	Change in component	(17.0		)	0.2			0.6			—			(16.2		)
	Reclassification adjustments into earnings	—			—			1.6			3.3			4.9
	Income tax effect	—			(0.1		)	(0.7		)	(1.3		)	(2.1		)
	Balance at March 31, 2013	14.4			(0.3		)	(43.0		)	(129.1		)	(158.0		)
	Change in component	(2.5		)	0.1			4.3			—			1.9
	Reclassification adjustments into earnings	—			—			1.6			3.6			5.2
	Income tax effect	—			—			(1.5		)	(1.3		)	(2.8		)
	Balance at June 30, 2013	11.9			(0.2		)	(38.6		)	(126.8		)	(153.7		)
	Change in component	32.9			1.1			18			—			52
	Reclassification adjustments into earnings	—			—			1.7			3.4			5.1
	Income tax effect	—			(0.4		)	(4.3		)	(1.3		)	(6.0		)
	Balance at September 30, 2013	$	44.8		$	0.5		$	(23.2	)	$	(124.7	)	$	(102.6	)

Financial_Data_of_Business_Seg1

Financial Data of Business Segments (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]
Segment data	The following tables show the profitability, financial position, and investment volume of each of our business segments (in millions):
		Rail North America			Rail International			ASC			Portfolio Management			Other			GATX Consolidated
	Three Months Ended September 30, 2013
	Profitability
	Revenues
	Lease revenue	$	192.2		$	45.6		$	1.1		$	7.8		$	—		$	246.7
	Marine operating revenue	—			—			73			16			—			89
	Other revenue	14.3			1.9			—			1.3			—			17.5
	Total Revenues	206.5			47.5			74.1			25.1			—			353.2
	Expenses
	Maintenance expense	58.6			10.9			7.4			—			—			76.9
	Marine operating expense	—			—			47.2			11			—			58.2
	Depreciation expense	44.9			10.8			4.1			5.8			—			65.6
	Operating lease expense	29.7			—			1.8			—			—			31.5
	Other operating expense	4.9			1.3			—			0.7			—			6.9
	Total Expenses	138.1			23			60.5			17.5			—			239.1
	Other Income (Expense)
	Net gain on asset dispositions	20.5			1.3			—			1.7			—			23.5
	Interest expense, net	(26.1		)	(6.7		)	(1.6		)	(6.3		)	(0.4		)	(41.1		)
	Other (expense) income	(4.8		)	(1.0		)	0.9			—			0.5			(4.4		)
	Share of affiliates' earnings (pre-tax)	(0.1		)	16.7			—			14.7			—			31.3
	Segment Profit	$	57.9		$	34.8		$	12.9		$	17.7		$	0.1		123.4
	Selling, general and administrative expense																42
	Income taxes (includes $3.7 of net tax benefits related to affiliates' earnings)																27.6
	Net Income																$	53.8
	Investment Volume
	Portfolio investments and capital additions	$	130.8		$	43.7		$	—		$	19.3		$	2.4		$	196.2
	Selected Balance Sheet Data at September 30, 2013
	Investments in affiliated companies	$	31.5		$	2.1		$	—		$	328.3		$	—		$	361.9
	Identifiable assets	$	3,781.60		$	1,269.60		$	285.5		$	851.5		$	150.9		$	6,339.10
		Rail North America			Rail International			ASC			Portfolio Management			Other			GATX Consolidated
	Three Months Ended September 30, 2012
	Profitability
	Revenues
	Lease revenue	$	180.7		$	40.1		$	1.1		$	9.6		$	—		$	231.5
	Marine operating revenue	—			—			79.1			6.4			—			85.5
	Other revenue	12.7			1.4			—			0.8			—			14.9
	Total Revenues	193.4			41.5			80.2			16.8			—			331.9
	Expenses
	Maintenance expense	51.3			9.8			7.7			—			—			68.8
	Marine operating expense	—			—			51.3			5.2			—			56.5
	Depreciation expense	42.2			8.9			4			5.6			—			60.7
	Operating lease expense	31.4			—			1.3			—			—			32.7
	Other operating expense	5.2			1.1			—			0.3			—			6.6
	Total Expenses	130.1			19.8			64.3			11.1			—			225.3
	Other Income (Expense)
	Net gain on asset dispositions	9.2			1			—			1.1			—			11.3
	Interest expense, net	(26.3		)	(6.1		)	(1.8		)	(6.9		)	(1.8		)	(42.9		)
	Other (expense) income	(1.8		)	(1.8		)	(0.9		)	0.3			0.3			(3.9		)
	Share of affiliates' earnings (pre-tax)	1.2			3.1			—			14.8			—			19.1
	Segment Profit (Loss)	$	45.6		$	17.9		$	13.2		$	15		$	(1.5	)	90.2
	Selling, general and administrative expense																38.6
	Income taxes (includes $0.5 of net tax benefits related to affiliates' earnings)																(2.2		)
	Net Income																$	53.8
	Investment Volume
	Portfolio investments and capital additions	$	81.9		$	41.4		$	0.3		$	6.3		$	1.7		$	131.6
	Selected Balance Sheet Data at December 31, 2012
	Investments in affiliated companies	$	46.9		$	77.2		$	—		$	377.9		$	—		$	502
	Identifiable assets	$	3,601.10		$	1,105.80		$	284.2		$	797.4		$	266.9		$	6,055.40
		Rail North America			Rail International			ASC			Portfolio Management			Other			GATX Consolidated
	Nine Months Ended September 30, 2013
	Profitability
	Revenues
	Lease revenue	$	563.3		$	132.2		$	3.2		$	24.2		$	—		$	722.9
Marine operating revenue	—			—			157			33.8			—			190.8
Other revenue	41.9			5.8			—			3			—			50.7
Total Revenues	605.2			138			160.2			61			—			964.4
Expenses
Maintenance expense	170.8			32			15.1			—			—			217.9
Marine operating expense	—			—			105.2			27.3			—			132.5
Depreciation expense	129.9			31.5			8.1			17.1			—			186.6
Operating lease expense	94			—			3.5			—			(0.1		)	97.4
Other operating expense	13.9			3.6			—			1.7			—			19.2
Total Expenses	408.6			67.1			131.9			46.1			(0.1		)	653.6
Other Income (Expense)
Net gain on asset dispositions	40.9			3.8			—			15.1			—			59.8
Interest expense, net	(80.5		)	(17.5		)	(4.8		)	(19.7		)	(2.7		)	(125.2		)
Other (expense) income	(8.9		)	(0.5		)	0.3			—			0.5			(8.6		)
Share of affiliates' earnings (pre-tax)	8.3			21.1			—			37.2			—			66.6
Segment Profit (Loss)	$	156.4		$	77.8		$	23.8		$	47.5		$	(2.1	)	303.4
Selling, general and administrative expense																129.8
Income taxes (includes $9.7 related to affiliates' earnings)																57.6
Net Income																$	116
Investment Volume
Portfolio investments and capital additions	$	345.9		$	134.9		$	11		$	170.5		$	4.5		$	666.8
	Rail North America			Rail International			ASC			Portfolio Management			Other			GATX Consolidated
Nine Months Ended September 30, 2012
Profitability
Revenues
Lease revenue	$	531.9		$	119.1		$	3.2		$	28.4		$	—		$	682.6
Marine operating revenue	—			—			166			20.1			—			186.1
Other revenue	36.6			3.9			—			2.3			—			42.8
Total Revenues	568.5			123			169.2			50.8			—			911.5
Expenses
Maintenance expense	148.1			34.6			14.8			—			—			197.5
Marine operating expense	—			—			108.6			16.6			—			125.2
Depreciation expense	125.7			26.1			7.9			16.2			—			175.9
Operating lease expense	94.1			—			2.5			0.2			(0.2		)	96.6
Other operating expense	13.6			4			(0.3		)	(0.7		)	—			16.6
Total Expenses	381.5			64.7			133.5			32.3			(0.2		)	611.8
Other Income (Expense)
Net gain on asset dispositions	39.7			3.1			—			14.8			—			57.6
Interest expense, net	(78.0		)	(19.0		)	(5.5		)	(20.6		)	(4.0		)	(127.1		)
Other (expense) income	(3.9		)	(3.3		)	(0.9		)	3.4			0.7			(4.0		)
Share of affiliates' earnings (pre-tax)	4.7			(16.9		)	—			35.5			—			23.3
Segment Profit (Loss)	$	149.5		$	22.2		$	29.3		$	51.6		$	(3.1	)	249.5
Selling, general and administrative expense																115.6
Income taxes (includes $4.0 related to affiliates' earnings)																26.3
Net Income																$	107.6
Investment Volume
Portfolio investments and capital additions	$	318.5		$	125.4		$	11.7		$	62.8		$	5		$	523.4

Description_of_Business_Detail

Description of Business (Details)	9 Months Ended
	Sep. 30, 2013
	Segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of business segments	4

Investments_in_Affiliated_Comp

Investments in Affiliated Companies Investments in Affililated Companies (Details)	9 Months Ended		3 Months Ended			9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
	USD ($)	USD ($)	Singco/Somagas [Member]	Aae Cargo Ag [Member]	Aae Cargo Ag [Member]	Aae Cargo Ag [Member]
			USD ($)	USD ($)	EUR (€)	USD ($)
Investments in and Advances to Affiliates [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent				37.50%	37.50%	37.50%
Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax				$9.30
gmt_SalePrice				114.1	84.5
Proceeds from Divestiture of Businesses and Interests in Affiliates			23		17
Portfolio Proceeds	$286.60	$260.20				$91.10	[1]
[1]	(b)In 2013, proceeds from the sale of our 37.5% interest in AAE included receipt of a note in the amount of $91.1 million.

Variable_Interest_Entities_Det

Variable Interest Entities (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Variable Interest Entity [Line Items]
Document Period End Date	30-Sep-13
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	$136.30		$111.40
Carrying amounts of assets and liabilities of the VIE
Non-Recourse Debt	75.2		130.6
Variable Interest, Held by Entity [Member]
Carrying amounts of assets and liabilities of the VIE
Operating assets, net of accumulated depreciation	94.4	[1]	98.4	[1]
Non-Recourse Debt	27.9		35.1
Investments in affiliates [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	$135.70		$110.70
[1]	All operating assets are pledged as collateral on the nonrecourse debt.

Variable_Interest_Entities_Det1

Variable Interest Entities (Details 1) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	$136.30	$111.40
Carrying amounts and maximum exposure to loss with respect to VIEs
Maximum Exposure to Loss	136.3	111.4
Investments in affiliates [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	135.7	110.7
Carrying amounts and maximum exposure to loss with respect to VIEs
Maximum Exposure to Loss	135.7	110.7
Other investment [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	0.6	0.7
Carrying amounts and maximum exposure to loss with respect to VIEs
Maximum Exposure to Loss	$0.60	$0.70

Fair_Value_Disclosure_Details

Fair Value Disclosure (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	$150	$100
Assets
Available for sale equity securities	4.8	3.3
Designated as Hedging Instrument [Member]
Assets
Interest rate derivatives	7.4	10.2	[1]
Liabilities
Interest rate derivatives	0.2	1	[1]
Not Designated as Hedging Instrument [Member]
Liabilities
Interest rate derivatives	0.2	0.3	[2]
Foreign exchange rate derivatives	1.4	2.1	[2]
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Available for sale equity securities	4.8	3.3
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Assets
Interest rate derivatives	0	0	[1]
Liabilities
Interest rate derivatives	0	0	[1]
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member]
Liabilities
Interest rate derivatives	0	0	[2]
Foreign exchange rate derivatives	0	0	[2]
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Available for sale equity securities	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Assets
Interest rate derivatives	7.4	10.2	[1]
Liabilities
Interest rate derivatives	0.2	1	[1]
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member]
Liabilities
Interest rate derivatives	0.2	0.3	[2]
Foreign exchange rate derivatives	1.4	2.1	[2]
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Available for sale equity securities	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Designated as Hedging Instrument [Member]
Assets
Interest rate derivatives	0	0	[1]
Liabilities
Interest rate derivatives	0	0	[1]
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Not Designated as Hedging Instrument [Member]
Liabilities
Interest rate derivatives	0	0	[2]
Foreign exchange rate derivatives	$0	$0	[2]
[1]	Designated as hedges
[2]	Not designated as hedges

Fair_Value_Disclosure_Details_

Fair Value Disclosure (Details 2) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value Hedges [Member]
Impact of GATX's Derivative Instrument on Income Statement and Other comprehensive income (loss)
Interest expense	($0.80)	($1.30)	($3.10)	($3.90)
Cash Flow Hedges [Member]
Impact of GATX's Derivative Instrument on Income Statement and Other comprehensive income (loss)
Unrealized gain on derivative instruments (effective portion)	-0.1	0.3	0.8	1
Non-designated [Member]
Impact of GATX's Derivative Instrument on Income Statement and Other comprehensive income (loss)
Other expense	-1.7	-2.1	0.6	-0.6
Operating Expense [Member] | Cash Flow Hedges [Member]
Impact of GATX's Derivative Instrument on Income Statement and Other comprehensive income (loss)
Effective portion reclassified from accumulated other comprehensive loss on derivative instruments	-0.4	-0.4	-1.1	-1.1
Interest Expense [Member] | Cash Flow Hedges [Member]
Impact of GATX's Derivative Instrument on Income Statement and Other comprehensive income (loss)
Effective portion reclassified from accumulated other comprehensive loss on derivative instruments	($1.30)	($1.10)	($3.80)	($4.10)

Fair_Value_Disclosure_Details_1

Fair Value Disclosure (Details 3) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Document Period End Date	30-Sep-13
Assets
Loans	$120.30	$27.20
Carrying Amount [Member]
Assets
Investment funds	1.7	2.5
Loans	120.3	27.2
Liabilities
Recourse fixed rate debt	2,684.80	2,343.30
Recourse floating rate debt	937	809.1
Nonrecourse debt	75.2	130.6
Fair Value [Member]
Assets
Investment funds	5.3	5.8
Loans	120.6	27.7
Liabilities
Recourse fixed rate debt	2,794.60	2,513.40
Recourse floating rate debt	947.2	807.9
Nonrecourse debt	$77.70	$138.20

Fair_Value_Disclosure_Details_2

Fair Value Disclosure (Details Textual) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012
Derivative [Line Items]
Derivative Asset	$150	$150	$100
Document Period End Date		30-Sep-13
Fair Value Disclosure (Textual) [Abstract]
Derivative Asset, Notional Amount	150	150	100
Derivative, Notional Amount	133.9	133.9	129.2
Cash flow hedge pre-tax loss to be reclassified within twelve months	6.3
Expected After tax reclassification of net losses from accumulated other comprehensive income to earnings in Next Twelve Months	4
Aggregate fair value of all derivative instruments with Net liability position	$0.40	$0.40
Fair Value Hedges [Member]
Fair Value Disclosure (Textual) [Abstract]
Number of instruments, outstanding	2	2	1
Maturity date range of hedge derivatives	2015-2018	2015-2018
Cash Flow Hedges [Member]
Fair Value Disclosure (Textual) [Abstract]
Number of instruments, outstanding	5	5	12
Maturity date range of hedge derivatives	2014-2020	2014-2020

Pension_and_Other_PostRetireme2

Pension and Other Post-Retirement Benefits (Details 2) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Defined Benefit Pension [Member]
Components of pension and other post retirement benefit costs
Service cost	$1.70		$1.50		$5.10		$4.50
Interest cost	4.6		4.9		13.8		14.8
Expected return on plan assets	-6.9		-7.4		-20.7		-22.2
Amortization of unrecognized prior service credit	-0.3	[1]	-0.3	[1]	-0.8	[1]	-0.8	[1]
Amortization of unrecognized net actuarial loss (gains)	3.7	[1]	2.5	[1]	11.2	[1]	7.5	[1]
Net costs	2.8		1.2		8.6		3.8
Retiree Health and Life [Member]
Components of pension and other post retirement benefit costs
Service cost	0.1		0.1		0.2		0.2
Interest cost	0.4		0.5		1.2		1.5
Expected return on plan assets	0		0		0		0
Amortization of unrecognized prior service credit	0	[1]	0	[1]	-0.1	[1]	-0.1	[1]
Amortization of unrecognized net actuarial loss (gains)	0	[1]	0	[1]	0	[1]	-0.1	[1]
Net costs	$0.50		$0.60		$1.30		$1.50
[1]	(a)Amounts are reclassified from accumulated other comprehensive loss.

Share_Based_Compensation_Detai

Share Based Compensation (Details) (USD $)	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted average estimated fair value	$18,890,000
Share-based Compensation Arrangement By Share-based Payment Award, Fair Value Assumptions, Expected Dividend Payment Rate	$0.30
Expected term of SARs	4 years 8 months 12 days
Risk-free interest rate	0.70%
Dividend yield	2.60%
Present Value of Dividends	$5,600,000
Expected stock price volatility	42.40%

Share_Based_Compensation_Detai1

Share Based Compensation (Details Textual) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share Based Compensation (Textual) [Abstract]
Share-based compensation expense	$3.10	$3	$9.50	$9.10
Tax benefits	$1.20	$1.10	$3.60	$3.40
Stock Option SAR Awards [Member]
Additional Share Based Compensation (Textual) [Abstract]
Stock awards			317,100,000,000
Restricted Stock and Performance Share Awards [Member]
Additional Share Based Compensation (Textual) [Abstract]
Stock awards			67,970,000,000
Phantom Stock Units [Member]
Additional Share Based Compensation (Textual) [Abstract]
Stock awards			68,780,000,000
Stock Options SARs Granted Since Two Thousand Four [Member]
Additional Share Based Compensation (Textual) [Abstract]
Stock awards			15,401,000,000

Income_Taxes_Details_Textual

Income Taxes (Details Textual) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Estimated Time Period for Recognition of Unrecognized Taxes		Within the next 12 months
Effective income tax rate		45.00%	20.00%
Tax On Gain Of Affiliate Sale	$23.20
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	3.9	3.9
Unrecognized Foreign Tax Benefits That May Be Recognized		0.4	15.5
Adjusted Tax Rate		27.00%	34.00%
Unrecognized tax benefits	4.7	4.7
Decrease in income tax expenses unrecognized tax benefits if recognized	4.7	4.7
Decrease In Income Tax Expenses Unrecognized Tax Benefits If Recognized Net Of Federal Tax	$3.20	$3.20

Commercial_Commitments_Details

Commercial Commitments (Details) (USD $)	Sep. 30, 2013		Apr. 29, 2013		Dec. 31, 2012
In Millions, unless otherwise specified
Guarantor Obligations [Line Items]
Total commercial commitments	$52	[1]			$104.50	[1]
Amount of liability included in recorded value of the company's commitment	5.7				6.4
Affiliate guarantees [Member]
Guarantor Obligations [Line Items]
Total commercial commitments	0	[2]	42	[2]	42	[2]
Asset residual value guarantees [Member]
Guarantor Obligations [Line Items]
Total commercial commitments	5.4				11.2
Lease payment guarantees [Member]
Guarantor Obligations [Line Items]
Total commercial commitments	36.3				41
Performance bonds [Member]
Guarantor Obligations [Line Items]
Total commercial commitments	1.4				0.6
Standby letters of credit [Member]
Guarantor Obligations [Line Items]
Total commercial commitments	$8.90				$9.70
[1]	The carrying values of liabilities on the balance sheet for our commercial commitments were $5.7 million at September 30, 2013, and $6.4 million at December 31, 2012. The expiration dates for our commitments range from 2014 to 2022.
[2]	No amount is provided for one of our guarantees that does not state a maximum potential future payment and for which we believe the likelihood that we will be required to perform under the guarantee is remote. In April 2013, $42.0 million of our affiliate guarantees were terminated.

Commercial_Commitments_Details1

Commercial Commitments (Details Textual)	3 Months Ended
	Sep. 30, 2013
	claim
Guarantees [Abstract]
Expiration of commitment range	2014 to 2022
Number of material claims made against workers' compensation and general liability insurance	0

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended			9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Numerator:
Net income	$53.80		$53.80	$116		$107.60
Denominator:
Weighted average shares outstanding - basic	46.2		46.9	46.5		46.8
Effect of dilutive securities:
Equity compensation plans	0.6		0.6	0.7		0.6
Convertible preferred stock		[1]	0.1		[1]	0.1
Weighted average shares outstanding - diluted	46.8		47.6	47.2		47.5
Basic earnings per share (in dollars per share)	$1.16		$1.15	$2.49		$2.30
Diluted earnings per share (in dollars per share)	$1.15		$1.13	$2.45		$2.26
[1]	Antidilutive

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income (Loss) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Foreign Currency Translation Gain (Loss) [Roll Forward]
Beginning Balance, Foreign Currency Translation Gain (Loss)	$11.90	$14.40	$31.40
Change in Foreign Currency Translation Gain (Loss)	32.9	-2.5	-17
Foreign Currency Translation Gain (Loss), Income tax effect	0	0	0
Ending Balance, Foreign Currency Translation Gain (Loss)	44.8	11.9	14.4
Unrealized Gain (Loss) on Securities [Roll Forward]
Beginning Balance, Unrealized Gain (Loss) on Securities	-0.2	-0.3	-0.4
Change in Unrealized Gain (Loss) on Securities	1.1	0.1	0.2
Unrealized Gain (Loss) on Securities, Reclassification adjustments into earnings	0	0	0
Unrealized Gain (Loss) on Securities, Income tax effect	-0.4	0	-0.1
Ending Balance, Unrealized Gain (Loss) on Securities	0.5	-0.2	-0.3
Unrealized Loss on Derivative Instruments [Roll Forward]
Beginning Balance, Unrealized Loss on Derivative Instruments	-38.6	-43	-44.5
Change in Unrealized Loss on Derivative Instruments	18	4.3	0.6
Unrealized Loss on Derivative Instruments, Reclassification adjustments into earnings	1.7	1.6	1.6
Unrealized Loss on Derivative Instruments, Income tax effect	-4.3	-1.5	-0.7
Ending Balance, Unrealized Loss on Derivative Instruments	-23.2	-38.6	-43
Postretirement Benefit Plans [Roll Forward]
Beginning Balance, Post-Retirement Benefit Plans	-126.8	-129.1	-131.1
Change in Post-Retirement Benefit Plans	0	0	0
Post-Retirement Benefit Plans, Reclassification adjustments into earnings	3.4	3.6	3.3
Post-Retirement Benefit Plans, Income tax effect	-1.3	-1.3	-1.3
Ending Balance, Post-Retirement Benefit Plans	-124.7	-126.8	-129.1
Other Comprehensive Income Change in Component	52	1.9	-16.2
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment Realized upon Sale or Liquidation, before Tax	0	0	0
Reclassification adjustments into earnings, Total	5.1	5.2	4.9
Income tax effect, Total	-6	-2.8	-2.1
Accumulated other comprehensive income (loss), net of tax	($102.60)	($153.70)	($158)	($144.60)

Legal_Proceedings_and_Other_Co1

Legal Proceedings and Other Contingencies (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 14, 2012	Jun. 29, 2009	Dec. 14, 2012	Jun. 29, 2009	Jun. 29, 2009
	claim	Viareggio [Member]	Viareggio [Member]	Derailed [Member]	Overturned [Member]	Punctured and Ignited [Member]
		affiliate_investment	Car	Viareggio [Member]	Viareggio [Member]	Viareggio [Member]
		Employee	casualty	Company	Car	Car
Loss Contingencies [Line Items]
Number of railars			14		5	1
Number of casualties			32
Number of subsidiaries		2
Number of companies				4
Number of employees		18
Loss Contingency, New Claims Filed, Number	110
Legal Fees	$4

Financial_Data_of_Business_Seg2

Financial Data of Business Segments (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
			Segment
Segment Reporting Information [Line Items]
Number of business segments			4
Income taxes related to affiliates' earnings	($3.70)	($0.50)	($9.70)	($4)
Profitability
Lease revenue	246.7	231.5	722.9	682.6
Marine operating revenue	89	85.5	190.8	186.1
Other Revenue, Net	17.5	14.9	50.7	42.8
Total Revenues	353.2	331.9	964.4	911.5
Maintenance expense	76.9	68.8	217.9	197.5
Marine operating expense	58.2	56.5	132.5	125.2
Depreciation	65.6	60.7	186.6	175.9
Operating lease expense	31.5	32.7	97.4	96.6
Other operating expense	6.9	6.6	19.2	16.6
Total Expenses	239.1	225.3	653.6	611.8
Net gain on asset dispositions	23.5	11.3	59.8	57.6
Interest expense, net	-41.1	-42.9	-125.2	-127.1
Other (expense) income	-4.4	-3.9	-8.6	-4
Share of affiliates' earnings (pre-tax)	31.3	19.1	66.6	23.3
Segment profit (loss)	123.4	90.2	303.4	249.5
Selling, general and administrative expense	42	38.6	129.8	115.6
Income taxes, including tax related to affiliates' earnings	27.6	-2.2	57.6	26.3
Net Income	53.8	53.8	116	107.6
Capital Expenditures
Portfolio investments and capital additions	196.2	131.6	666.8	523.4
Selected Balance Sheet Data
Investments in affiliated companies	361.9	502	361.9	502	502
Identifiable assets	6,339.10	6,055.40	6,339.10	6,055.40	6,055.40
Rail North America [Member]
Segment Reporting Information [Line Items]
Number of affiliate investments	2		2
Leverage level expressed as a ratio of recourse debt to equity			5
Profitability
Lease revenue	192.2	180.7	563.3	531.9
Marine operating revenue	0	0	0	0
Other Revenue, Net	14.3	12.7	41.9	36.6
Total Revenues	206.5	193.4	605.2	568.5
Maintenance expense	58.6	51.3	170.8	148.1
Marine operating expense	0	0	0	0
Depreciation	44.9	42.2	129.9	125.7
Operating lease expense	29.7	31.4	94	94.1
Other operating expense	4.9	5.2	13.9	13.6
Total Expenses	138.1	130.1	408.6	381.5
Net gain on asset dispositions	20.5	9.2	40.9	39.7
Interest expense, net	-26.1	-26.3	-80.5	-78
Other (expense) income	-4.8	-1.8	-8.9	-3.9
Share of affiliates' earnings (pre-tax)	-0.1	1.2	8.3	4.7
Segment profit (loss)	57.9	45.6	156.4	149.5
Capital Expenditures
Portfolio investments and capital additions	-130.8	-81.9	-345.9	-318.5
Selected Balance Sheet Data
Investments in affiliated companies	31.5	46.9	31.5	46.9
Identifiable assets	3,781.60	3,601.10	3,781.60	3,601.10
Rail International [Member]
Segment Reporting Information [Line Items]
Number of affiliate investments	1		1
Leverage level expressed as a ratio of recourse debt to equity			2
Profitability
Lease revenue	45.6	40.1	132.2	119.1
Marine operating revenue	0	0	0	0
Other Revenue, Net	1.9	1.4	5.8	3.9
Total Revenues	47.5	41.5	138	123
Maintenance expense	10.9	9.8	32	34.6
Marine operating expense	0	0	0	0
Depreciation	10.8	8.9	31.5	26.1
Operating lease expense	0	0	0	0
Other operating expense	1.3	1.1	3.6	4
Total Expenses	23	19.8	67.1	64.7
Net gain on asset dispositions	1.3	1	3.8	3.1
Interest expense, net	-6.7	-6.1	-17.5	-19
Other (expense) income	-1	-1.8	-0.5	-3.3
Share of affiliates' earnings (pre-tax)	16.7	3.1	21.1	-16.9
Segment profit (loss)	34.8	17.9	77.8	22.2
Capital Expenditures
Portfolio investments and capital additions	-43.7	-41.4	-134.9	-125.4
Selected Balance Sheet Data
Investments in affiliated companies	2.1	77.2	2.1	77.2
Identifiable assets	1,269.60	1,105.80	1,269.60	1,105.80
ASC [Member]
Segment Reporting Information [Line Items]
Leverage level expressed as a ratio of recourse debt to equity			1.5
Profitability
Lease revenue	1.1	1.1	3.2	3.2
Marine operating revenue	73	79.1	157	166
Other Revenue, Net	0	0	0	0
Total Revenues	74.1	80.2	160.2	169.2
Maintenance expense	7.4	7.7	15.1	14.8
Marine operating expense	47.2	51.3	105.2	108.6
Depreciation	4.1	4	8.1	7.9
Operating lease expense	1.8	1.3	3.5	2.5
Other operating expense	0	0	0	-0.3
Total Expenses	60.5	64.3	131.9	133.5
Net gain on asset dispositions	0	0	0	0
Interest expense, net	-1.6	-1.8	-4.8	-5.5
Other (expense) income	0.9	-0.9	0.3	-0.9
Share of affiliates' earnings (pre-tax)	0	0	0	0
Segment profit (loss)	12.9	13.2	23.8	29.3
Capital Expenditures
Portfolio investments and capital additions	0	-0.3	-11	-11.7
Selected Balance Sheet Data
Investments in affiliated companies	0	0	0	0
Identifiable assets	285.5	284.2	285.5	284.2
Portfolio Management [Member]
Segment Reporting Information [Line Items]
Leverage level expressed as a ratio of recourse debt to equity			3
Profitability
Lease revenue	7.8	9.6	24.2	28.4
Marine operating revenue	16	6.4	33.8	20.1
Other Revenue, Net	1.3	0.8	3	2.3
Total Revenues	25.1	16.8	61	50.8
Maintenance expense	0	0	0	0
Marine operating expense	11	5.2	27.3	16.6
Depreciation	5.8	5.6	17.1	16.2
Operating lease expense	0	0	0	0.2
Other operating expense	0.7	0.3	1.7	-0.7
Total Expenses	17.5	11.1	46.1	32.3
Net gain on asset dispositions	1.7	1.1	15.1	14.8
Interest expense, net	-6.3	-6.9	-19.7	-20.6
Other (expense) income	0	0.3	0	3.4
Share of affiliates' earnings (pre-tax)	14.7	14.8	37.2	35.5
Segment profit (loss)	17.7	15	47.5	51.6
Capital Expenditures
Portfolio investments and capital additions	-19.3	-6.3	-170.5	-62.8
Selected Balance Sheet Data
Investments in affiliated companies	328.3	377.9	328.3	377.9
Identifiable assets	851.5	797.4	851.5	797.4
Other [Member]
Profitability
Lease revenue	0	0	0	0
Marine operating revenue	0	0	0	0
Other Revenue, Net	0	0	0	0
Total Revenues	0	0	0	0
Maintenance expense	0	0	0	0
Marine operating expense	0	0	0	0
Depreciation	0	0	0	0
Operating lease expense	0	0	-0.1	-0.2
Other operating expense	0	0	0	0
Total Expenses	0	0	-0.1	-0.2
Net gain on asset dispositions	0	0	0	0
Interest expense, net	-0.4	-1.8	-2.7	-4
Other (expense) income	0.5	0.3	0.5	0.7
Share of affiliates' earnings (pre-tax)	0	0	0	0
Segment profit (loss)	0.1	-1.5	-2.1	-3.1
Capital Expenditures
Portfolio investments and capital additions	-2.4	-1.7	-4.5	-5
Selected Balance Sheet Data
Investments in affiliated companies	0	0	0	0
Identifiable assets	$150.90	$266.90	$150.90	$266.90