Financial Data of Business Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Profitability
Revenues	$ 284.5	$ 265.0
Share of affiliates' earnings	5.5	17.1
Total Gross Income	290.0	282.1
Ownership costs	129.7	129.8
Other costs and expenses	78.7	90.1
Segment profit (loss)	81.6	62.2
SG&A	38.1	36.4
Income before Income Taxes	43.5	25.8
Capital Expenditures
Portfolio investments and capital additions	(153.7)	(96.2)
Selected Balance Sheet Data
Investments in Affiliated Companies	509.1		513.8
Identifiable assets	5,792.9		5,857.5
Rail [Member]
Profitability
Revenues	244.4	236.8
Share of affiliates' earnings	(2.0)	7.1
Total Gross Income	242.4	243.9
Ownership costs	113.9	115.0
Other costs and expenses	69.9	77.3
Segment profit (loss)	58.6	51.6
Capital Expenditures
Portfolio investments and capital additions	143.7	53.9
Selected Balance Sheet Data
Investments in Affiliated Companies	137.7		142.2
Identifiable assets	4,514.2		4,443.4
Financial Data of Business Segments (Textual) [Abstract]
Leverage level expressed as a ratio of recourse debt to equity	4
ASC [Member]
Profitability
Revenues	11.8	12.1
Total Gross Income	11.8	12.1
Ownership costs	1.8	2.0
Other costs and expenses	7.9	9.3
Segment profit (loss)	2.1	0.8
Capital Expenditures
Portfolio investments and capital additions	5.9	5.2
Selected Balance Sheet Data
Identifiable assets	274.4		276.1
Financial Data of Business Segments (Textual) [Abstract]
Leverage level expressed as a ratio of recourse debt to equity	1.5
Portfolio Management [Member]
Profitability
Revenues	28.1	15.9
Share of affiliates' earnings	7.5	10.0
Total Gross Income	35.6	25.9
Ownership costs	12.7	11.8
Other costs and expenses	0.9	3.4
Segment profit (loss)	22.0	10.7
Capital Expenditures
Portfolio investments and capital additions	3.1	36.4
Selected Balance Sheet Data
Investments in Affiliated Companies	371.4		371.6
Identifiable assets	830.6		844.0
Financial Data of Business Segments (Textual) [Abstract]
Leverage level expressed as a ratio of recourse debt to equity	3
Other [Member]
Profitability
Revenues	0.2	0.2
Total Gross Income	0.2	0.2
Ownership costs	1.3	1.0
Other costs and expenses		0.1
Segment profit (loss)	(1.1)	(0.9)
Capital Expenditures
Portfolio investments and capital additions	1.0	0.7
Selected Balance Sheet Data
Identifiable assets	$ 173.7		$ 294.0