v3.25.2
Debt - Components of debt (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Apr. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Debt Instrument [Line Items]        
Debt: $ 5,856.8     $ 5,690.9
Recourse        
Debt Instrument [Line Items]        
Debt: 598.1     597.8
Nonrecourse        
Debt Instrument [Line Items]        
Debt: 5,258.7     5,093.1
Level 2        
Debt Instrument [Line Items]        
Long-term Debt, Fair Value 624.8     623.2
Level 3        
Debt Instrument [Line Items]        
Long-term Debt, Fair Value 3,368.6     3,430.5
Corporate Segment [Member]        
Debt Instrument [Line Items]        
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 603.7     604.3
Less: unamortized debt issuance costs 5.6     6.5
7.75% Senior Notes Due 2028 | Senior Notes due 2028 | Corporate Segment [Member]        
Debt Instrument [Line Items]        
Senior Notes 603.7     604.3
Debt Instrument, Unamortized Premium 3.7     4.3
Wholly Owned Subsidiaries [Member] | Nonrecourse        
Debt Instrument [Line Items]        
Debt: 4,217.2     4,021.3
Wholly Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member]        
Debt Instrument [Line Items]        
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 4,235.1     4,036.6
Less: unamortized debt issuance costs 17.9     15.3
Wholly Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member] | Nonrecourse        
Debt Instrument [Line Items]        
Debt: 4,217.2     4,021.3
Wholly Owned Subsidiaries [Member] | Secured Debt [Member] | Railcar Leasing and Services Group [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Unamortized Discount 0.3     0.3
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 2,389.8     2,447.3
Wholly Owned Subsidiaries [Member] | 2017 Secured Railcar Equipment Notes [Member] [Domain] | Promissory Notes [Member] | Railcar Leasing and Services Group [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Unamortized Discount 0.0     1.5
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 0.0     631.3
Wholly Owned Subsidiaries [Member] | TRL-2023 Term Loan | Line of Credit [Member] | Railcar Leasing and Services Group [Member]        
Debt Instrument [Line Items]        
Long-term Line of Credit 1,044.9 $ 1,050.0 $ 320.7 323.4
Debt Instrument, Unamortized Discount 0.7     0.0
Wholly Owned Subsidiaries [Member] | Other Equipment Financing | Railcar Leasing and Services Group [Member]        
Debt Instrument [Line Items]        
Secured Debt, Other 48.9     50.0
Partially-Owned Subsidiaries [Member] | Nonrecourse        
Debt Instrument [Line Items]        
Debt: 1,041.5     1,071.8
Partially-Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member]        
Debt Instrument [Line Items]        
Less: unamortized debt issuance costs 3.8     5.0
Partially-Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member] | Nonrecourse        
Debt Instrument [Line Items]        
Debt: 1,041.5     1,071.8
Partially-Owned Subsidiaries [Member] | Secured Debt [Member] | Railcar Leasing and Services Group [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Unamortized Discount 0.1     0.1
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 1,045.3     1,076.8
Revolving Credit Facility [Member] | Line of Credit [Member] | Corporate Segment [Member]        
Debt Instrument [Line Items]        
Long-term Line of Credit 0.0     0.0
Revolving Credit Facility [Member] | TILC [Member] | TILC Warehouse Facility [Member] | Line of Credit [Member] | Railcar Leasing and Services Group [Member]        
Debt Instrument [Line Items]        
Long-term Line of Credit $ 751.5     $ 584.6