Property, Plant, and Equipment (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Components of property, plant, and equipment
Less accumulated depreciation	$ (1,491.9)	[1]	$ (1,343.0)
Property, plant, and equipment, net before adjustment to net deferred profit	5,349.9		4,861.7
Net deferred profit on railcars sold to the Leasing Group	(648.6)		(562.7)
Property, plant, and equipment, net	4,701.3	[1]	4,299.0
Partially-owned subsidiaries
Components of property, plant, and equipment
Less accumulated depreciation	(189.4)	[1]	(153.8)
Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	1,395.3		1,260.1
Less accumulated depreciation	(766.3)		(720.8)
Property, plant, and equipment, net before adjustment to net deferred profit	629.0		539.3
Leasing Group
Components of property, plant, and equipment
Net deferred profit on railcars sold to the Leasing Group	(648.6)		(562.7)
Leasing Group | Wholly-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment	3,500.8		3,241.5
Less accumulated depreciation	(536.2)		(468.4)
Property, plant, and equipment, net before adjustment to net deferred profit	2,964.6		2,773.1
Leasing Group | Partially-owned subsidiaries
Components of property, plant, and equipment
Property, plant, and equipment, net before adjustment to net deferred profit	1,756.3		1,549.3
Land | Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	42.5		37.7
Buildings and improvements | Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	453.0		431.0
Machinery and other | Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	842.5		745.3
Machinery and other | Leasing Group | Wholly-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment	10.1		9.6
Construction in progress | Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	57.3		46.1
Equipment on lease | Leasing Group | Wholly-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment	3,490.7		3,231.9
Equipment on lease | Leasing Group | Partially-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment	1,945.7		1,703.1
Less accumulated depreciation	$ (189.4)		$ (153.8)

[1] (unaudited)