Property, Plant, and Equipment (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Components of property, plant, and equipment
Less accumulated depreciation	$ (1,392.6)	[1]	$ (1,343.0)
Property, plant, and equipment, net before adjustment to net deferred profit	5,049.4		4,861.7
Net deferred profit on railcars sold to the Leasing Group	(587.4)		(562.7)
Property, plant, and equipment, net	4,462.0	[1]	4,299.0	[2]
Partially-owned subsidiary
Components of property, plant, and equipment
Less accumulated depreciation	162.4	[1]	153.8
Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	1,328.6		1,260.1	[2]
Less accumulated depreciation	(738.1)		(720.8)	[2]
Property, plant, and equipment, net before adjustment to net deferred profit	590.5		539.3	[2]
Net deferred profit on railcars sold to the Leasing Group	0		0
Property, plant, and equipment, net	590.5		539.3
Leasing Group | Wholly-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment	3,840.9		3,672.2	[2]
Less accumulated depreciation	(492.1)		(468.4)	[2]
Equipment Pledged as Collateral for Specific Segment Debt	2,561.9
Property, plant, and equipment, net before adjustment to net deferred profit	3,348.8		3,203.8	[2]
Net deferred profit on railcars sold to the Leasing Group	(408.1)		(381.8)	[2]
Property, plant, and equipment, net	2,940.7		2,822.0
Leasing Group | Partially-owned subsidiary
Components of property, plant, and equipment
Property, plant and equipment	1,272.5		1,272.4	[2]
Less accumulated depreciation	(162.4)		(153.8)	[2]
Property, plant, and equipment, net before adjustment to net deferred profit			1,118.6	[2]
Net deferred profit on railcars sold to the Leasing Group	(179.3)		(180.9)	[2]
Property, plant, and equipment, net	930.8		937.7
Land | Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	40.8		37.7	[2]
Buildings and improvements | Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	436.5		431.0	[2]
Machinery and other | Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	803.9		745.3	[2]
Machinery and other | Leasing Group | Wholly-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment	9.7		9.6	[2]
Construction in progress | Manufacturing/Corporate
Components of property, plant, and equipment
Property, plant and equipment	47.4		46.1	[2]
Equipment on lease | Leasing Group | Wholly-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment	$ 3,831.2		$ 3,662.6	[2]

[1] (unaudited)

[2] (as reported)