Financial Data of Business Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013 Segment	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Provision for Income Taxes, Equity Method Investment									$ 16.5	$ 2.0	$ 8.2
Number of business segments									4
Profitability
Lease revenue									975.2	917.0	900.1
Marine operating revenue									275.1	265.5	230.0
Other revenue									70.7	60.7	61.3
Total Revenues	356.6	353.2	338.9	272.3	331.7	331.9	323.1	256.5	1,321.0	1,243.2	1,191.4
Maintenance expense									294.0	269.7	277.6
Marine operating expense									189.8	182.4	165.6
Depreciation									255.0	237.4	226.5
Operating lease expense									129.4	130.2	132.0
Other operating expense									26.1	24.2	27.8
Total Expenses									894.3	843.9	829.5
Net gain on asset dispositions									85.6	79.5	65.8
Interest expense, net									(166.6)	(166.6)	(168.9)
Other (expense) income									(8.4)	(8.2)	4.1
Share of affiliates' earnings (pre-tax)									92.3	21.6	40.6
Segment profit (loss)									429.6	325.6	303.5
SG&A									178.3	160.2	155.3
Income tax benefit									65.5	26.1	29.2
Net Income	53.3	53.8	35.1	27.1	29.7	53.8	23.5	30.3	169.3	137.3	110.8
Selected Balance Sheet Data
Investments in affiliated companies	354.3				502.0				354.3	502.0	513.8
Identifiable assets	6,549.6				6,055.4				6,549.6	6,055.4	5,857.5
Capital Expenditures
Portfolio investments and capital additions									859.6	770.0	614.6
Rail North America [Member]
Segment Reporting Information [Line Items]
Leverage level expressed as a ratio of recourse debt to equity									5
Profitability
Lease revenue									758.9	713.9	690.9
Marine operating revenue									0	0	0
Other revenue									58.2	51.4	51.5
Total Revenues									817.1	765.3	742.4
Maintenance expense									228.2	201.4	206.1
Marine operating expense									0	0	0
Depreciation									176.7	167.7	162.5
Operating lease expense									124.4	126.5	130.9
Other operating expense									18.4	18.5	18.8
Total Expenses									547.7	514.1	518.3
Net gain on asset dispositions									67.7	58.6	52.1
Interest expense, net									(106.0)	(101.9)	(101.7)
Other (expense) income									(9.8)	(5.1)	(5.7)
Share of affiliates' earnings (pre-tax)									10.3	6.5	3.9
Segment profit (loss)									231.6	209.3	172.7
Selected Balance Sheet Data
Investments in affiliated companies	31.4				46.9				31.4	46.9	54.0
Identifiable assets	3,710.5				3,601.1				3,710.5	3,601.1	3,540.2
Capital Expenditures
Portfolio investments and capital additions									(502.4)	465.9	280.5
Rail International [Member]
Segment Reporting Information [Line Items]
Leverage level expressed as a ratio of recourse debt to equity									2
Profitability
Lease revenue									180.2	161.2	160.5
Marine operating revenue									0	0	0
Other revenue									8.8	6.5	7.8
Total Revenues									189.0	167.7	168.3
Maintenance expense									42.9	46.6	52.1
Marine operating expense									0	0	0
Depreciation									43.2	36.1	33.6
Operating lease expense									0	0	0
Other operating expense									5.3	5.1	4.2
Total Expenses									91.4	87.8	89.9
Net gain on asset dispositions									3.7	1.7	0
Interest expense, net									(23.9)	(24.5)	(25.4)
Other (expense) income									(1.1)	(6.1)	7.2
Share of affiliates' earnings (pre-tax)									21.1	(18.3)	0.5
Segment profit (loss)									97.4	32.7	60.7
Selected Balance Sheet Data
Investments in affiliated companies	2.0				77.2				2.0	77.2	88.2
Identifiable assets	1,297.1				1,105.8				1,297.1	1,105.8	903.2
Capital Expenditures
Portfolio investments and capital additions									(168.5)	200.1	140.8
ASC [Member]
Segment Reporting Information [Line Items]
Leverage level expressed as a ratio of recourse debt to equity									1.5
Profitability
Lease revenue									4.2	4.3	4.2
Marine operating revenue									223.5	239.1	212.2
Other revenue									0	0	0
Total Revenues									227.7	243.4	216.4
Maintenance expense									22.9	21.7	19.4
Marine operating expense									151.3	160.3	151.7
Depreciation									12.1	11.9	11.3
Operating lease expense									5.2	3.8	0
Other operating expense									0	(0.3)	0
Total Expenses									191.5	197.4	182.4
Net gain on asset dispositions									(1.3)	0	1.1
Interest expense, net									(6.2)	(7.1)	(7.7)
Other (expense) income									0.2	(1.4)	(0.1)
Share of affiliates' earnings (pre-tax)									0	0	0
Segment profit (loss)									28.9	37.5	27.3
Selected Balance Sheet Data
Investments in affiliated companies	0				0				0	0	0
Identifiable assets	271.0				284.2				271.0	284.2	276.1
Capital Expenditures
Portfolio investments and capital additions									(11.2)	12.6	17.4
Portfolio Management [Member]
Segment Reporting Information [Line Items]
Leverage level expressed as a ratio of recourse debt to equity									3
Profitability
Lease revenue									31.9	37.6	44.5
Marine operating revenue									51.6	26.4	17.8
Other revenue									3.7	2.8	2.0
Total Revenues									87.2	66.8	64.3
Maintenance expense									0	0	0
Marine operating expense									38.5	22.1	13.9
Depreciation									23.0	21.7	19.1
Operating lease expense									0	0.2	1.4
Other operating expense									2.4	0.9	4.3
Total Expenses									63.9	44.9	38.7
Net gain on asset dispositions									15.5	19.2	12.6
Interest expense, net									(26.7)	(27.7)	(29.6)
Other (expense) income									1.4	3.4	2.8
Share of affiliates' earnings (pre-tax)									60.9	33.4	36.2
Segment profit (loss)									74.4	50.2	47.6
Selected Balance Sheet Data
Investments in affiliated companies	320.9				377.9				320.9	377.9	371.6
Identifiable assets	856.9				797.4				856.9	797.4	844.0
Capital Expenditures
Portfolio investments and capital additions									(170.5)	83.5	172.0
Other [Member]
Profitability
Lease revenue									0	0	0
Marine operating revenue									0	0	0
Other revenue									0	0	0
Total Revenues									0	0	0
Maintenance expense									0	0	0
Marine operating expense									0	0	0
Depreciation									0	0	0
Operating lease expense									(0.2)	(0.3)	(0.3)
Other operating expense									0	0	0.5
Total Expenses									(0.2)	(0.3)	0.2
Net gain on asset dispositions									0	0	0
Interest expense, net									(3.8)	(5.4)	(4.5)
Other (expense) income									0.9	1.0	(0.1)
Share of affiliates' earnings (pre-tax)									0	0	0
Segment profit (loss)									(2.7)	(4.1)	(4.8)
Selected Balance Sheet Data
Investments in affiliated companies	0				0				0	0	0
Identifiable assets	414.1				266.9				414.1	266.9	294.0
Capital Expenditures
Portfolio investments and capital additions									(7.0)	7.9	3.9
Parent [Member]
Profitability
Income tax benefit									$ 82.0	$ 28.1	$ 37.4