Property, Plant, and Equipment (Details) - USD ($) $ in Millions	Mar. 31, 2017		Dec. 31, 2016
Components of property, plant, and equipment
Property, plant and equipment, at cost	$ 8,161.1	[1]	$ 7,981.0
Less accumulated depreciation	(2,081.0)	[1]	(2,014.2)
Property, plant, and equipment, net	6,080.1	[1]	5,966.8
Manufacturing/ Corporate
Components of property, plant, and equipment
Property, plant and equipment, at cost	1,955.8		1,936.1
Less accumulated depreciation	(999.8)		(974.4)
Property, plant, and equipment, net	956.0		961.7
Partially-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment, at cost	1,979.8	[1]	1,979.8
Less accumulated depreciation	(378.0)	[1]	(364.9)
Land | Manufacturing/ Corporate
Components of property, plant, and equipment
Property, plant and equipment, at cost	105.7		103.3
Buildings and improvements | Manufacturing/ Corporate
Components of property, plant, and equipment
Property, plant and equipment, at cost	647.7		642.6
Machinery and other | Manufacturing/ Corporate
Components of property, plant, and equipment
Property, plant and equipment, at cost	1,163.9		1,151.1
Construction in progress | Manufacturing/ Corporate
Components of property, plant, and equipment
Property, plant and equipment, at cost	38.5		39.1
Operating Segments
Components of property, plant, and equipment
Property, plant, and equipment, net	6,899.7		6,764.9
Operating Segments | Manufacturing/ Corporate
Components of property, plant, and equipment
Property, plant, and equipment, net	956.0		961.7
Operating Segments | Leasing Group | Wholly-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment, at cost	4,873.0		4,683.7
Less accumulated depreciation	(793.2)		(760.1)
Property, plant, and equipment, net	4,079.8		3,923.6
Operating Segments | Leasing Group | Partially-owned subsidiaries
Components of property, plant, and equipment
Property, plant, and equipment, net	1,863.9		1,879.6
Operating Segments | Machinery and other | Leasing Group | Wholly-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment, at cost	10.7		10.7
Operating Segments | Equipment on lease | Leasing Group | Wholly-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment, at cost	4,862.3		4,673.0
Operating Segments | Equipment on lease | Leasing Group | Partially-owned subsidiaries
Components of property, plant, and equipment
Property, plant and equipment, at cost	2,309.2		2,309.4
Less accumulated depreciation	(445.3)		(429.8)
Net deferred profit on railcars sold to the Leasing Group
Components of property, plant, and equipment
Property, plant and equipment, at cost	(976.9)		(948.2)
Less accumulated depreciation	157.3		150.1
Property, plant, and equipment, net	$ (819.6)		$ (798.1)

[1] (unaudited)