v3.26.3
Debt - Components of debt (Details) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
Debt Instrument [Line Items]    
Debt: $ 5,325.0 $ 5,442.5
Level 2    
Debt Instrument [Line Items]    
Long-term Debt, Fair Value 608.6 623.9
Level 3    
Debt Instrument [Line Items]    
Long-term Debt, Fair Value 2,970.7 3,303.6
Recourse    
Debt Instrument [Line Items]    
Debt: 598.9 598.5
Nonrecourse    
Debt Instrument [Line Items]    
Debt: 4,726.1 4,844.0
Corporate Segment [Member]    
Debt Instrument [Line Items]    
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 602.2 603.1
Less: unamortized debt issuance costs 3.3 4.6
7.75% Senior Notes Due 2028 | Senior Notes due 2028 | Corporate Segment [Member]    
Debt Instrument [Line Items]    
Senior Notes 602.2 603.1
Debt Instrument, Unamortized Premium 2.2 3.1
Wholly Owned Subsidiaries [Member] | Nonrecourse    
Debt Instrument [Line Items]    
Debt: 4,726.1 4,573.4
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 4,747.3 4,594.3
Less: unamortized debt issuance costs 21.2 20.9
Wholly Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member] | Nonrecourse    
Debt Instrument [Line Items]    
Debt: 4,726.1 4,573.4
Wholly Owned Subsidiaries [Member] | Secured Debt [Member] | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Unamortized Discount 0.4 0.3
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 3,041.5 3,036.3
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 1,006.6 1,031.9
Debt Instrument, Unamortized Discount 0.5 0.6
Wholly Owned Subsidiaries [Member] | Other Equipment Financing | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Secured Debt, Other 45.7 47.6
Partially-Owned Subsidiaries [Member] | Nonrecourse    
Debt Instrument [Line Items]    
Debt: 0.0 270.6
Partially-Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Less: unamortized debt issuance costs 0.0 0.7
Partially-Owned Subsidiaries [Member] | Railcar Leasing and Services Group [Member] | Nonrecourse    
Debt Instrument [Line Items]    
Debt: 0.0 270.6
Partially-Owned Subsidiaries [Member] | Secured Debt [Member] | Railcar Leasing and Services Group [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Unamortized Discount 0.0 0.0
Debt, Net of Unamortized Premium and Unamortized Discount, Gross of Unamortized Debt Issuance Costs 0.0 271.3
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 $ 653.5 $ 478.5