Financial Data of Business Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Segment	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of business segments			4
Income taxes related to affiliates' earnings	$ (3.7)	$ (0.5)	$ (9.7)	$ (4.0)
Profitability
Lease revenue	246.7	231.5	722.9	682.6
Marine operating revenue	89.0	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)	(4.0)
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	42.0	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	116.0	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	502.0	361.9	502.0	502.0
Identifiable assets	6,339.1	6,055.4	6,339.1	6,055.4	6,055.4
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			5.0
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	94.0	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)	(78.0)
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	3,781.6	3,601.1	3,781.6	3,601.1
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			2.0
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	138.0	123.0
Maintenance expense	10.9	9.8	32.0	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	4.0
Total Expenses	23.0	19.8	67.1	64.7
Net gain on asset dispositions	1.3	1.0	3.8	3.1
Interest expense, net	(6.7)	(6.1)	(17.5)	(19.0)
Other (expense) income	(1.0)	(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	1,269.6	1,105.8	1,269.6	1,105.8
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	73.0	79.1	157.0	166.0
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	4.0	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)	(11.0)	(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			3.0
Profitability
Lease revenue	7.8	9.6	24.2	28.4
Marine operating revenue	16.0	6.4	33.8	20.1
Other Revenue, Net	1.3	0.8	3.0	2.3
Total Revenues	25.1	16.8	61.0	50.8
Maintenance expense	0	0	0	0
Marine operating expense	11.0	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	15.0	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)	(4.0)
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)	(5.0)
Selected Balance Sheet Data
Investments in affiliated companies	0	0	0	0
Identifiable assets	$ 150.9	$ 266.9	$ 150.9	$ 266.9