Note 7. Property, Plant, and Equipment Property, Plant, and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	$ 9,539.6	$ 9,272.6
Less accumulated depreciation, including partially-owned subsidiaries of $644.7 and $599.0	2,534.8	2,385.8
Property, Plant and Equipment, Net	7,004.8	6,886.8
Intersegment Eliminations [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	(1,061.3)	(1,050.7)
NegativeAccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	311.1	287.4
Property, Plant and Equipment, Net	(750.2)	(763.3)
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Net	7,413.9	7,309.4
Manufacturing and Corporate [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	798.5	823.9
Less accumulated depreciation, including partially-owned subsidiaries of $644.7 and $599.0	457.4	483.2
Property, Plant and Equipment, Net	341.1	340.7
Manufacturing and Corporate [Member] | Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	16.1	15.7
Manufacturing and Corporate [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	380.1	384.6
Manufacturing and Corporate [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	391.6	405.5
Manufacturing and Corporate [Member] | Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	10.7	18.1
Wholly Owned Subsidiaries [Member] | Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	7,565.8	7,269.0
Less accumulated depreciation, including partially-owned subsidiaries of $644.7 and $599.0	1,625.1	1,480.9
Property, Plant and Equipment, Net	5,940.7	5,788.1
Wholly Owned Subsidiaries [Member] | Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	26.8	21.7
Wholly Owned Subsidiaries [Member] | Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Railcars on Lease [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	7,539.0	7,247.3
Partially-Owned Subsidiaries [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	1,922.5	1,917.6
Less accumulated depreciation, including partially-owned subsidiaries of $644.7 and $599.0	644.7	599.0
Partially-Owned Subsidiaries [Member] | Railcar Leasing and Management Services Group [Member] | Operating Segments [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Net	1,473.2	1,521.3
Partially-Owned Subsidiaries [Member] | Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Railcars on Lease [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,922.5 and $1,917.6	2,236.6	2,230.4
Less accumulated depreciation, including partially-owned subsidiaries of $644.7 and $599.0	$ 763.4	$ 709.1