Note 7. Property, Plant, and Equipment Property, Plant, and Equipment (Details) - USD ($) $ in Millions		Dec. 31, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,920.5 and $1,922.5		$ 9,751.1	$ 9,539.6
Less accumulated depreciation, including partially-owned subsidiaries of $690.0 and $644.7		2,763.0	2,534.8
Property, Plant and Equipment, Net		6,988.1	7,004.8
Railcars on Lease [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Net		6,631.6	6,654.8
Intersegment Eliminations [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,920.5 and $1,922.5	[1]	(1,069.8)	(1,061.3)
NegativeAccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment		337.3	311.1
Property, Plant and Equipment, Net		(732.5)	(750.2)
Wholly Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member] | Operating Segments [Member]
Property, Plant and Equipment [Line Items]
Less accumulated depreciation, including partially-owned subsidiaries of $690.0 and $644.7		1,766.9	1,604.9
Property, Plant and Equipment, Net		5,948.1	5,931.8
Wholly Owned Subsidiaries [Member] | Railcar Leasing and 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 $1,920.5 and $1,922.5		7,715.0	7,536.7
Partially-Owned Subsidiaries [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,920.5 and $1,922.5		1,920.5	1,922.5
Less accumulated depreciation, including partially-owned subsidiaries of $690.0 and $644.7		690.0	644.7
Partially-Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member] | Operating Segments [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Net		1,416.0	1,473.2
Partially-Owned Subsidiaries [Member] | Railcar Leasing and 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 $1,920.5 and $1,922.5		2,233.1	2,236.6
Less accumulated depreciation, including partially-owned subsidiaries of $690.0 and $644.7		817.1	763.4
Operating and Administrative [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,920.5 and $1,922.5		872.8	827.6
Less accumulated depreciation, including partially-owned subsidiaries of $690.0 and $644.7		516.3	477.6
Property, Plant and Equipment, Net		356.5	350.0
Operating and Administrative [Member] | Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,920.5 and $1,922.5		16.3	16.1
Operating and Administrative [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,920.5 and $1,922.5		403.2	380.4
Operating and Administrative [Member] | Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,920.5 and $1,922.5		441.8	419.8
Operating and Administrative [Member] | Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, at cost, including partially-owned subsidiaries of $1,920.5 and $1,922.5		$ 11.5	$ 11.3

[1] Includes deferred profit related to new railcar additions, sustainable railcar conversions, railcar modifications, and other betterments. The deferred profit is subsequently eliminated in consolidation.