Financial Data of Business Segments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) Segment	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Lease Income	$ 286.2	$ 279.1	$ 845.1	$ 804.0
Cargo and Freight Revenue	77.6	98.9	167.8	188.8
Provision for Income Taxes, Equity Method Investment	(2.8)	4.6	$ 3.2	14.2
Number of business segments | Segment			4
Profitability
Other revenue	22.4	19.2	$ 58.3	56.8
Maintenance expense	83.9	85.6	242.4	242.7
Depreciation expense	75.0	71.9	217.9	201.7
Marine operating expense	48.5	64.8	114.7	134.4
Operating lease expense	22.3	27.4	65.4	81.6
Other operating expense	8.3	8.0	23.4	21.3
Total Expenses	238.0	257.7	663.8	681.7
Disposition gains on owned assets	17.4	1.2	60.4	41.6
Residual sharing income	7.6	1.2	11.0	8.0
Nonremarketing disposition gains	1.6	4.0	9.3	13.4
Asset impairment	(31.1)	(0.1)	(31.2)	(0.4)
Net gain on asset dispositions	(4.5)	6.3	49.5	62.6
Interest expense, net	(37.7)	(38.1)	(117.1)	(119.6)
Other (expense) income	(3.1)	(3.1)	(8.7)	(11.4)
Income (Loss) From Equity Method Investment, Before Tax	(1.5)	17.0	22.0	48.8
Segment profit (loss)	101.4	121.6	353.1	348.3
SG&A	44.4	45.8	134.7	133.4
Income tax benefit	20.3	19.9	68.1	54.2
Net Income	39.5	51.3	147.1	146.5
Revenues	386.2	397.2	1,071.2	1,049.6
Selected Balance Sheet Data
Portfolio Investments and Capital Additions	142.1	171.5	498.3	826.6
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	(364.1)		(364.1)		$ (357.7)
Identifiable assets	(6,904.7)		(6,904.7)		(6,937.5)
Rail North America [Member]
Segment Reporting Information [Line Items]
Lease Income	234.9	222.6	694.3	635.7
Cargo and Freight Revenue	0.0	0.0	$ 0.0	0.0
Leverage level expressed as a ratio of recourse debt to equity			5
Profitability
Other revenue	20.3	15.7	$ 51.8	46.4
Maintenance expense	66.7	65.7	199.7	192.2
Depreciation expense	54.5	49.7	160.1	140.3
Marine operating expense	0.0	0.0	0.0	0.0
Operating lease expense	20.6	25.6	62.0	78.2
Other operating expense	6.8	6.1	18.1	16.1
Total Expenses	148.6	147.1	439.9	426.8
Disposition gains on owned assets	10.2	1.2	51.1	40.5
Residual sharing income	0.3	0.1	0.7	4.5
Nonremarketing disposition gains	1.0	3.1	2.6	8.1
Asset impairment	0.0	0.0	0.0	0.0
Net gain on asset dispositions	11.5	4.4	54.4	53.1
Interest expense, net	(27.0)	(24.1)	(76.1)	(74.0)
Other (expense) income	(1.2)	(1.0)	(4.2)	(4.7)
Income (Loss) From Equity Method Investment, Before Tax	0.1	0.1	0.4	7.6
Segment profit (loss)	90.0	70.6	280.7	237.3
Revenues	255.2	238.3	746.1	682.1
Selected Balance Sheet Data
Portfolio Investments and Capital Additions	97.8	118.9	362.8	660.7
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	(12.3)		(12.3)		17.2
Identifiable assets	(4,599.0)		(4,599.0)		4,358.3
Rail International [Member]
Segment Reporting Information [Line Items]
Lease Income	44.1	47.9	128.6	142.8
Cargo and Freight Revenue	0.0	0.0	$ 0.0	0.0
Leverage level expressed as a ratio of recourse debt to equity			2
Profitability
Other revenue	1.7	2.3	$ 5.3	6.7
Maintenance expense	9.9	11.0	28.2	34.1
Depreciation expense	11.1	11.9	32.6	35.4
Marine operating expense	0.0	0.0	0.0	0.0
Operating lease expense	(0.1)	0.0	0.0	0.0
Other operating expense	1.1	1.2	3.5	3.6
Total Expenses	22.0	24.1	64.3	73.1
Disposition gains on owned assets	0.0	0.0	0.0	0.6
Residual sharing income	0.0	0.0	0.0	0.0
Nonremarketing disposition gains	0.6	0.9	6.7	5.3
Asset impairment	(0.1)	(0.1)	(0.2)	(0.1)
Net gain on asset dispositions	0.5	0.8	6.5	5.8
Interest expense, net	(7.0)	(6.0)	(16.5)	(18.4)
Other (expense) income	(1.8)	(1.1)	(3.0)	(3.8)
Income (Loss) From Equity Method Investment, Before Tax	0.0	(0.1)	(0.2)	(0.2)
Segment profit (loss)	15.5	19.7	56.4	59.8
Revenues	45.8	50.2	133.9	149.5
Selected Balance Sheet Data
Portfolio Investments and Capital Additions	40.9	45.6	110.1	127.2
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	1.5		1.5		1.8
Identifiable assets	1,140.6		1,140.6		1,229.4
ASC [Member]
Segment Reporting Information [Line Items]
Lease Income	1.1	1.1	3.1	3.2
Cargo and Freight Revenue	61.7	82.7	$ 119.7	145.2
Leverage level expressed as a ratio of recourse debt to equity			1.5
Profitability
Other revenue	0.0	0.0	$ 0.0	0.0
Maintenance expense	7.3	8.9	14.5	16.4
Depreciation expense	4.7	4.5	9.6	8.9
Marine operating expense	36.7	52.2	77.7	97.9
Operating lease expense	1.8	1.8	3.5	3.5
Other operating expense	0.0	0.0	0.0	0.0
Total Expenses	50.5	67.4	105.3	126.7
Disposition gains on owned assets	0.0	0.0	0.0	0.0
Residual sharing income	0.0	0.0	0.0	0.0
Nonremarketing disposition gains	0.0	0.0	0.0	0.0
Asset impairment	0.0	0.0	0.0	(0.4)
Net gain on asset dispositions	0.0	0.0	0.0	(0.4)
Interest expense, net	(1.4)	(1.4)	(4.0)	(4.2)
Other (expense) income	0.0	0.2	(0.1)	0.0
Income (Loss) From Equity Method Investment, Before Tax	0.0	0.0	0.0	0.0
Segment profit (loss)	10.9	15.2	13.4	17.1
Revenues	62.8	83.8	122.8	148.4
Selected Balance Sheet Data
Portfolio Investments and Capital Additions	0.8	0.9	20.3	16.9
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0.0		0.0		0.0
Identifiable assets	297.0		297.0		286.7
Portfolio Management [Member]
Segment Reporting Information [Line Items]
Lease Income	6.1	7.5	19.1	22.3
Cargo and Freight Revenue	15.9	16.2	$ 48.1	43.6
Leverage level expressed as a ratio of recourse debt to equity			3
Profitability
Other revenue	0.4	1.2	$ 1.2	3.7
Maintenance expense	0.0	0.0	0.0	0.0
Depreciation expense	4.7	5.8	15.6	17.1
Marine operating expense	11.8	12.6	37.0	36.5
Operating lease expense	0.0	0.0	0.0	0.0
Other operating expense	0.4	0.7	1.8	1.6
Total Expenses	16.9	19.1	54.4	55.2
Disposition gains on owned assets	7.2	0.0	9.3	0.5
Residual sharing income	7.3	1.1	10.3	3.5
Nonremarketing disposition gains	0.0	0.0	0.0	0.0
Asset impairment	(31.0)	0.0	(31.0)	0.1
Net gain on asset dispositions	(16.5)	1.1	(11.4)	4.1
Interest expense, net	(4.7)	(5.8)	(15.5)	(18.7)
Other (expense) income	0.0	(1.4)	0.0	(1.1)
Income (Loss) From Equity Method Investment, Before Tax	(1.6)	17.0	21.8	41.4
Segment profit (loss)	(17.3)	16.7	8.9	40.1
Revenues	22.4	24.9	68.4	69.6
Selected Balance Sheet Data
Portfolio Investments and Capital Additions	1.9	5.0	2.2	17.0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	(350.3)		(350.3)		(338.7)
Identifiable assets	(737.7)		(737.7)		(813.3)
Other [Member]
Segment Reporting Information [Line Items]
Lease Income	0.0	0.0	0.0	0.0
Cargo and Freight Revenue	0.0	0.0	0.0	0.0
Profitability
Other revenue	0.0	0.0	0.0	0.0
Maintenance expense	0.0	0.0	0.0	0.0
Depreciation expense	0.0	0.0	0.0	0.0
Marine operating expense	0.0	0.0	0.0	0.0
Operating lease expense	0.0	0.0	(0.1)	(0.1)
Other operating expense	0.0	0.0	0.0	0.0
Total Expenses	0.0	0.0	(0.1)	(0.1)
Disposition gains on owned assets	0.0	0.0	0.0	0.0
Residual sharing income	0.0	0.0	0.0	0.0
Nonremarketing disposition gains	0.0	0.0	0.0	0.0
Asset impairment	0.0	0.0	0.0	0.0
Net gain on asset dispositions	0.0	0.0	0.0	0.0
Interest expense, net	2.4	(0.8)	(5.0)	(4.3)
Other (expense) income	(0.1)	0.2	(1.4)	(1.8)
Income (Loss) From Equity Method Investment, Before Tax	0.0	0.0	0.0	0.0
Segment profit (loss)	2.3	(0.6)	(6.3)	(6.0)
Revenues	0.0	0.0	0.0	0.0
Selected Balance Sheet Data
Portfolio Investments and Capital Additions	0.7	1.1	2.9	4.8
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0.0		0.0		0.0
Identifiable assets	(130.4)		(130.4)		$ (249.8)
Parent [Member]
Profitability
Income tax benefit	17.5	$ 24.5	$ 71.3	$ 68.4
Cardinal Marine [Domain]
Profitability
Asset impairment	19.0
Cardinal Marine [Domain] | Portfolio Management [Member]
Profitability
Asset impairment	$ 49.8